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Core Content and Skills
Science Biology R
2007-2008
BOE Approved
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Go over syllabus
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Go over lab rules
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Safety
Measurement and Graphing
Microscope
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Using Metric Rulers and conversions
Using a graduated cylinder
Creating and Drawing Conlusions from Graphs
Microscope parts, Calculating Magnification, Field of View size and orientation, Use of Microscope, Wet mounts and Staining
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Students will correctly perform the iodine test to test for polysaccharrides.
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| Life Processes and Homeostasis |
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organism- a living thing
organic- is living or once was living
inorganic- nonliving
Most carbon compounds with the exception of carbon dioxide are organic.
Water is the most common inorganic compound in living things. It composes 80-95% of living organisms.
Scientists have been unable to agree on a single definition that characterizes life.
LIFE FUNCTIONS: (in all organisms including humans)
1. Nutrition- the obtaining and processing of materials by an organism for its use
(a.) ingestion- food intake by an organism
(b.) digestion- breakdown of complex foods to simpler foods by an organism
2. Circulation - distribution of materials within an organism
3. Movement- change in position by a living thing
4. Respiration- process used by organisms to release the energy in their food
(ex. oxygen + glucose yields carbon dioxide + water + ENERGY)
** The energy released in respiration is needed to maintain life functions.
5. Synthesis- combining simpler chemical substances to form more complex ones
(ex. starches from simple sugars)
6. Excretion- the removal of cellular waste products
7. Regulation (coordination)
- the control of the various activities of an organism (mostly involves the nervous system and endocrine glands in complex organisms)
8. growth- increase in living matter by increasing cell size or numbers
9. reproduction- ability of living things to form more of their own kind
** Not needed for organism survival--but necessary for the survival of the species.
10. immunity -- the ability of an organism to resist disease causing organisms and foreign invaders
Metabolism- the sum total of all life processes needed to sustain life
Homeostasis- the maintenance of an internal stable environment by an organism (steady state)
A disruption in any organism system will result in a corresponding disruption of homeostasis.
Organisms possess a control mechanisms that detect changes in the internal (or external) environment and make adjustments to correct the situation.
[Some Examples of Maintaining Homeostasis in Living Things]
1.) environmental temp increases ----> more sweating ---> more evaporation --> cools down body
2.) Blood sugar regulation
insulin -- a hormone (chemical messenger) produced by the pancreas and carried through the blood
-- lowers blood sugar 2 major ways:
a.) Takes glucose into our cells to be used as fuel in cell respiration from our blood
b.) Converts excess glucose to the glycogen (animal starch) and stores it in our liver and muscles
glucagon -- another pancreas hormone which can convert glycogen back to glucose if our sugar level is too low
The failure to maintain blood glucose homeostasis results in diabetes.
3.) Plant leaf regulation of water balance inside them.
stomata -- microscopic holes in a leaf which allow for exchange of water vapor out of the plant
(and other gases in and out of the leaf)
guard cells -- open and close the stomata
Changes in the stomata controlled by guard cells regulate the rate of water loss and gas exchange by many plants.
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1. correctly define the terms biology, inorganic, and organic.
2. recognize that water is the most common inorganic compound in living things.
3. correctly define the following terms; nutrition, ingestion, digestion, circulation, movement,
respiration, synthesis, excretion, regulation, growth, reproduction, and immunity.
4. define the term metabolism and relate it to the functioning of an organism.
5. define the term homeostasis.
6. recognize that a disruption in any organism system will result in a corresponding
disruption of homeostasis.
7. recognize that organisms possess a diverse set of control mechanisms that detect
changes in the internal or external environment and make adjustments to correct
the situation.
8. explain the homeostatic regulation of body temperature in humans.
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Calculating Magnification
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Identify the ocular lens, objective lens, diaphragm, arm, body tube, stage, stage clips, and light source from picture of a microscope
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Identify the functions of the ocular lens, objective lens, diaphragm, arm, body tube, stage, stage clips, and light source.
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Be able to draw the image of the a specimen seen through the microscope.
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Be able to draw the image of the a specimen seen through the microscope.
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Know which may to move the specimen to keep it in the field of view
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As magnification increases, field of view decreases
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Microscope parts, Calculating Magnification, Field of View size and orientation, Use of Microscope, Wet mounts and Staining
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Introduction to Chemistry
Inorganic Chemistry
pH and pH Indicators
Organic Chemistry and Indicators
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.[Basic Organic Compounds in Living Things]
I. Carbohydrates:
-- include sugars and complex carbohydrates (starches)
-- contain the elements carbon, hydrogen, and oxygen (the hydrogen is in a 2:1 ratio to oxygen)
a.) monosaccharides (simple sugars)
-- all have the formula C6 H12 O6
-- all have a single ring structure (glucose is an example)
b.) disaccharides (double sugars)
-- all have the formula C12 H22 O11
-- sucrose (table sugar) is an example
c.) Polysaccharides (formed of three or more simple sugar units)
glycogen -- animal starch stored in the liver and muscles
cellulose -- indigestible in humans -- forms cell walls
starches -- used as energy storage
How are complex carbohydrates formed and broken down?
1.) dehydration synthesis -- combining simple molecules to form a more complex one with the removal of water
ex. monosaccharide + monosaccharide ----> disaccharide + water
(C6H12O6 + C6H12O6 ----> C12H22O11 + H2O
-- polysaccharides are formed from repeated dehydration syntheses of water
2.) hydrolysis -- the addition of water to a compound to split it into smaller subunits
(also called chemical digestion)
ex. disaccharide + H2O ---> monosaccharide + monosaccharide
C12H22O11 + H2O ---> C6H12O6 + C6H12O6
3. Lipids (Fats) : exs. fats, oils, waxes, steroids
-- lipids chiefly function in energy storage, protection, and insulation
-- contain carbon, hydrogen, and oxygen but the H:O is not in a 2:1 ratio
lipids tend to be large molecules -- an example of a neutral lipid is below
-- neutral lipids are formed from the union of one glycerol molecule and 3 fatty acids
3 fatty acids + glycerol ----> neutral fat (lipid)
-- fats -- found chiefly in animals
-- oils and waxes -- found chiefly in plants
-- oils are liquid at room temperature, waxes are solids
-- lipids along with proteins are key components of cell membranes
-- steroids are special lipids used to build many reproductive hormones and cholesterol
III. Proteins:
-- contain the elements carbon, hydrogen, oxygen, and nitrogen
-- composed of amino acid subunits (below is the structure of an amino acid)
[Major Protein Functions]
1. Growth and repair
2. Energy
3. Buffer -- helps keep body pH constant
dipeptide -- formed from two amino acid subunits
Dehydration synthesis of a dipeptide
amino acid + amino acid ----- dipeptide + water
Hydrolysis of a dipeptide
dipeptide + H2O ---> amino acid + amino acid
polypeptide (protein) -- is composed of three or more amino acids linked by synthesis reactions
Examples of proteins include insulin, hemoglobin, and enzymes.
** There are an extremely large number of different proteins. The bases for variability include differences in the number, kinds and sequences of amino acids in the proteins
IV. Nucleic Acids: present in all cells
DNA (deoxyribonucleic acid)
-- contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins
-- found in the chromosomes of the nucleus (and a few other organelles)
RNA (ribonucleic acid)
-- directs cellular protein synthesis
-- found in ribosomes & nucleoli
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catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself
enzymes: organic catalysts made of protein
-- most enzyme names end in -ase
-- enzymes lower the energy needed to start a chemical rx. (activation energy)
-- begin to be destroyed above 45 C. (above this temperature all proteins begin to be destroyed)
It is thought that, in order for an enzyme to affect the rate of a reaction, the following events must take place.
1. The enzyme must form a temporary association with the substate forming the enzyme-substrate complex
2. The
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Complete Benedict's Solution Test for carbohydrates and determine if a carbohydrate is a simple or complex sugar
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Students will correctly perform the iodine test to test for polysaccharrides.
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Students will perform Buiret solution test for proteins and animo acid sequences
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Identify the Independent, Dependent Variables, control group, experiment group, and constants in an experiment.
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Designing a successful lab in order to test a claim.
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1. Define the 3 parts of the cell theory
2. Know 2 reasons why viruses do not work with the cell theory
3. Identify all the cell organelles and their functions
4. Identify a plant and animal cell
5. Know the 4 levels of organization (cell, tissue, organ, system)
6. Define the fluid mosaic model
7. Know the parts of the cell membrane
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1. discuss and compare the following relative organizational levels; cell, tissue, organ,
and organ systems.
2. recognize that improvements in the light microscope and microscopic techniques
during the last four centuries have allowed the development of the cell theory.
3. state the cell theory.
4. convert micrometer measurements to millimeters and vice versa.
5. describe the appearance and chief function(s) of the following organelles found in
both plant and animal cells; nucleus, nuclear membrane, nucleolus, ribosomes,
endoplasmic reticulum, cytoplasm, food vacuole, contractile vacuole, lysosome,
mitochondrion, golgi apparatus, and plasma membrane.
6. relate the structure of the plasma membrane to its function.
7. discuss the role of the centriole in animal cells.
8. state the role of the cell wall and chloroplasts in plant cells.
9. define the following terms associated with processes of the plasma membrane;
diffusion, concentration gradient, osmosis, solute, solvent, permeability, and
semi permeable.
10. given osmotic situations, correctly indicate the direction of osmotic flow and explain
why this is so.
11. explain the differences between passive transport and active transport.
12. explain the difference between pinocytosis and phagocytosis.
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Molecules are in constant motion
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Molecules move from high to low concentrations
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Active Transport moves molecules from low to high concentrations
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Molecules move down their concentration gradient
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Channel Proteins allow larger molecules to move through the membrane
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Active transport requires energy
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Selectively Permeable means the membrane only allows certain molecules to pass through.
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Students will construct a semipermeable membrane and determine why certain molecules will diffuse across the membrane while other molecules will not diffuse across the membrane
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Students will be able to predict and see the effects of hypertonic, hypotonic, and isotonic solutions on elodea leaf cells.
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.[Basic Organic Compounds in Living Things]
I. Carbohydrates:
-- include sugars and complex carbohydrates (starches)
-- contain the elements carbon, hydrogen, and oxygen (the hydrogen is in a 2:1 ratio to oxygen)
a.) monosaccharides (simple sugars)
-- all have the formula C6 H12 O6
-- all have a single ring structure (glucose is an example)
b.) disaccharides (double sugars)
-- all have the formula C12 H22 O11
-- sucrose (table sugar) is an example
c.) Polysaccharides (formed of three or more simple sugar units)
glycogen -- animal starch stored in the liver and muscles
cellulose -- indigestible in humans -- forms cell walls
starches -- used as energy storage
How are complex carbohydrates formed and broken down?
1.) dehydration synthesis -- combining simple molecules to form a more complex one with the removal of water
ex. monosaccharide + monosaccharide ----> disaccharide + water
(C6H12O6 + C6H12O6 ----> C12H22O11 + H2O
-- polysaccharides are formed from repeated dehydration syntheses of water
2.) hydrolysis -- the addition of water to a compound to split it into smaller subunits
(also called chemical digestion)
ex. disaccharide + H2O ---> monosaccharide + monosaccharide
C12H22O11 + H2O ---> C6H12O6 + C6H12O6
3. Lipids (Fats) : exs. fats, oils, waxes, steroids
-- lipids chiefly function in energy storage, protection, and insulation
-- contain carbon, hydrogen, and oxygen but the H:O is not in a 2:1 ratio
lipids tend to be large molecules -- an example of a neutral lipid is below
-- neutral lipids are formed from the union of one glycerol molecule and 3 fatty acids
3 fatty acids + glycerol ----> neutral fat (lipid)
-- fats -- found chiefly in animals
-- oils and waxes -- found chiefly in plants
-- oils are liquid at room temperature, waxes are solids
-- lipids along with proteins are key components of cell membranes
-- steroids are special lipids used to build many reproductive hormones and cholesterol
III. Proteins:
-- contain the elements carbon, hydrogen, oxygen, and nitrogen
-- composed of amino acid subunits (below is the structure of an amino acid)
[Major Protein Functions]
1. Growth and repair
2. Energy
3. Buffer -- helps keep body pH constant
dipeptide -- formed from two amino acid subunits
Dehydration synthesis of a dipeptide
amino acid + amino acid ----- dipeptide + water
Hydrolysis of a dipeptide
dipeptide + H2O ---> amino acid + amino acid
polypeptide (protein) -- is composed of three or more amino acids linked by synthesis reactions
Examples of proteins include insulin, hemoglobin, and enzymes.
** There are an extremely large number of different proteins. The bases for variability include differences in the number, kinds and sequences of amino acids in the proteins
IV. Nucleic Acids: present in all cells
DNA (deoxyribonucleic acid)
-- contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins
-- found in the chromosomes of the nucleus (and a few other organelles)
RNA (ribonucleic acid)
-- directs cellular protein synthesis
-- found in ribosomes & nucleoli
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catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself
enzymes: organic catalysts made of protein
-- most enzyme names end in -ase
-- enzymes lower the energy needed to start a chemical rx. (activation energy)
-- begin to be destroyed above 45 C. (above this temperature all proteins begin to be destroyed)
It is thought that, in order for an enzyme to affect the rate of a reaction, the following events must take place.
1. The enzyme must form a temporary association with the substr
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Complete Benedict's Solution Test for carbohydrates and determine if a carbohydrate is a simple or complex sugar
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Students will perform Buiret solution test for proteins and animo acid sequences
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Students will perform iodine solution test to test for polysaccharrides
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All cells come from preexisting cells
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Cells are the basic unit of structure and function of all living things
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Virus can be classified as living and nonliving
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Where did the first cell come from?
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Plants have cell walls and chloroplasts. Animal cells have centrioles
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Mitochondria: powerhouse of the cell, Nucleus: brain center of the cell, Cell membrane: selectively permeable membrane protects cell, Rough Endoplasmic Reticulum: transport system of cell that has ribosomes, Smooth ER: transport system without ribosomes, Ribosomes: site of protein synthesis, Golgi bodies: label and package materials in cell. Centrioles: help in cell reproduction, Vacuoles: storage for materials and wastes, Lysosomes: digest materials and contain digestive enzymes
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Cells form tissues, tissues for an organ, and organs work together to make an organ system.
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1. Identify the various parts of the cell and name their function.
2. Chart the similarities and differences of cell organelle with human organs.
3. Name each cell organelle, describe it's function and compare it to the human organ that has the same or similar function.
4. Use a microscope to look at plant and animal cells and find and label the various organelle on a diagram.
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Respiration: a process that occurs continuously in all organisms
-- It involves the transfer of the stored chemical energy in food molecules to a form readily usable by organisms.
-- It usually also involves an exchange of gases between the organism and the environment.
[Cellular Respiration]
-- those enzyme-controlled reactions in which the potential energy of organic molecules, such as glucose, is transferred to a more available form of energy. (ATP)
ATP (adenosine triphosphate) -- a more available form of energy used by the cell
** When ATP is hydrolyzed, energy is released and ADP (adenosine diphosphate) is formed. (The bonds between the phosphate groups are high in energy which is released when these bonds are broken.)
** This energy can be used to power those metabolic activities which require energy.
HOH + ATP -------------> ADP + P + Energy
(ATP-ase)
** This reaction is reversible.
aerobic respiration: if molecular oxygen is used in the release of energy from ATP
anaerobic respiration: if molecular oxygen is not used
[ANAEROBIC RESPIRATION]
(FERMENTATION)
-- is carried on in some cells lacking the enzymes necessary for aerobic respiration
-- may be carried out in many other cells when oxygen is lacking
Lactic Acid Fermentation (Glycolysis)
-- glucose is gradually broken down in a series of enzyme controlled reactions to lactic acid (anaerobic respiration)
Glucose ---------- 2 Lactic Acid + 2 ATP
-- Lactic acid is produced in animals and is associated with muscle fatigue.
-- Lactic acid is also produced by some bacteria and is important in the production of cheeses, buttermilk, and yogurt.
** As a result of anaerobic respiration, there is a net gain of 2 ATP.
2. Ethyl Alcohol Fermentation
-- important to the brewing and baking industries
-- yields a small amount of usable energy for some yeast and bacteria
glucose --> 2 ethyl alcohol + 2 carbon dioxide + 2 ATP
AEROBIC RESPIRATION
-- Many of the enzymes involved in aerobic cellular respiration are located in the mitochondria.
-- In the process with the presence of oxygen, the chemical energy of glucose is released gradually in a series of enzyme-controlled reactions.
-- Aerobic respiration is much more efficient than anaerobic respiration.
SUMMARY EQN:
glucose + oxygen ----------> water + carbon dioxide + 36 ATP
The energy from ATP is used by organisms to obtain, transform, and transport materials, and to eliminate wastes.
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Photosynthesis: process by which plants convert light energy to the chemical energy of organic molecules (glucose)
The energy for life (photosynthesis) comes primarily from the Sun.
Word eq'n:
Carbon dioxide + water -------> glucose + oxygen
(sunlight) (enzymes)
chloroplasts: organelles that carry on photosynthesis
chlorophylls: variety of pigments within the chloroplasts
The process of photosynthesis uses chlorophyll to trap solar energy which is then used to combine the inorganic molecules carbon dioxide and water into energy-rich organic compounds (e.g., glucose) and release oxygen to the environment.
These chlorophyll pigments may be separated according to their various
chemical charges by a technique known as chromatography. A description of the
chromatography process can be viewed at the link below
Paper Chromatography of Chlorophyll
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The glucose which is formed in photosynthesis may be:
1. Used as an energy source in cellular respiration.
2. Synthesized into other metabolic compounds. These compounds could include proteins, DNA, starch, and fats. The chemical energy stored in the bonds of these molecules can be used to provide energy for other life processes.
3. Converted into storage products by dehydration synthesis and other reactions for later use.
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1. define the term respiration and recognize that the process involves gas
exchange between the organism and its environment.
2. state the overall equation for aerobic cellular respiration.
3. explain the significance of the energy conversions involved in cellular respiration.
4. explain what ATP is and its significance.
5. explain how ATP is converted to ADP and explain what the energy released
may be used for.
6. explain the difference between aerobic respiration and anaerobic respiration.
7. explain the process of alcohol fermentation and its significance.
8. state the equation for lactic acid fermentation and explain how this may lead
to muscle fatigue.
9. recognize that the process of aerobic cellular respiration occurs in the mitochondria
using many enzyme controlled steps.
10. recognize that aerobic respiration is much more efficient in the production of ATP
than anaerobic respiration.
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Photosynthesis: process by which plants convert light energy to the chemical energy of organic molecules (glucose)
The energy for life (photosynthesis) comes primarily from the Sun.
Word eq'n:
Carbon dioxide + water -------> glucose + oxygen
(sunlight) (enzymes)
chloroplasts: organelles that carry on photosynthesis
chlorophylls: variety of pigments within the chloroplasts
The process of photosynthesis uses chlorophyll to trap solar energy which is then used to combine the inorganic molecules carbon dioxide and water into energy-rich organic compounds (e.g., glucose) and release oxygen to the environment.
These chlorophyll pigments may be separated according to their various
chemical charges by a technique known as chromatography. A description of the
chromatography process can be viewed at the link below
Paper Chromatography of Chlorophyll
The glucose which is formed in photosynthesis may be:
1. Used as an energy source in cellular respiration.
2. Synthesized into other metabolic compounds. These compounds could include proteins, DNA, starch, and fats. The chemical energy stored in the bonds of these molecules can be used to provide energy for other life processes.
3. Converted into storage products by dehydration synthesis and other reactio
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1. explain the purpose of the process of photosynthesis for a plant.
2. state the overall equation for photosynthesis.
3. list several factors which improve the efficiency of the photosynthetic process.
4. explain the role of chlorophyll and chloroplasts in photosynthesis.
5. discuss the process of chromatography in reference to the separation of plant pigments.
6. state several uses for the glucose formed in photosynthesis.
7. recognize that algae and green plants are organisms which carry on photosynthesis.
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Classification--grouping of different types of organisms based upon similarities in structure and evolutionary relationships
Carolus Linneaus--devised binomial nomenclature (2 names in Latin) Genus-Species
ex. scientific name of humans ..... Homo sapiens
Homo is the genus name .... sapiens is the species name.
Note that scientific names have the genus name starting with a capital letter and are underlined.
Taxomonic Hierarchy
Kingdom
Phylum
Class
Order
Family
Genus
Species
** The species is the fundamental unit of classification.
Organisms become more closely related but their groupings smaller as you
move down the taxonomic hierarchy.
The 6 Kingdom System is based on the following criteria:
1. Presence or absence of a nuclear membrane
2. Unicellularity versus multicellularity
3. Type of nutrition
(Kingdoms of Living Things)
1. Archaebacteria
-- most primitive and often live in extreme environments
-- unicellular and no nucleus
2. Monera
--bacteria and blue green algae
--have a primitive cell structure
--have no organized nucleus or nuclear membrane
3. Protista
--predominately unicellular organisms with plant or animal-like characteristics
--examples include protozoa and all algae except the blue-green
--have a true nucleus and nuclear membrane
4. Kingdom Fungi
--examples include yeasts, molds, and mushrooms
--cells are usually organized into branched, multinucleate filaments which absorb digested food from the external environment
5. Animal Kingdom
-- consist of multi-cellular organisms which ingest their food
6. Plant Kingdom
--possess chloroplasts and cell walls--make their own food
--are multicellular
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MORE ON PROTISTA
[Protista Examples]
Protozoa -- predominantly animal-like in their mode of nutrition
algae -- primarily plant-like in their mode of nutrition
Specific examples of protists (protozoa) include the ameba, paramecium, euglena, and spirogyra. (alga)
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1. explain what organism classification is and the purpose of this.
2. state the role of Linnaeus in devising the current classification scheme.
3. describe the taxonomic hierarchical sequence and recognize that as you move
down this sequence, the organisms involved are in smaller, more closely related
groups.
4. explain the criteria for the current six kingdom system of classification.
5. list the six major kingdoms of living things and state some basic characteristics
and examples of these.
6. distinguish between Protozoa and Algae.
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evolution--process of change through time
Evolution includes the change in characteristics of populations through generations.
Thus, existing life forms have evolved from earlier life forms.
Evolutionary theory is a unifying principle for the biological sciences.
It provides an explanation for the differences in structure, function, and behavior
among life forms.
Through radioactive dating with uranium, geologists
estimate the age of the earth at about 4.6 billion years. (It is assumed that the earth
is at least as old as the oldest rocks and minerals composing its crust.)
fossils: direct or indirect remains of organisms preserved in media such as sedimentary rock, amber, ice, or tar
Fossils have been found that indicate organisms existed well over 3 billion years ago. These organisms were simple, single-celled organisms.
Law of Superposition: the higher up you go in an undisturbed rock stratum, the
younger the rock layers become
** Upper, undisturbed strata generally contain fossils of more complex organisms,
whereas, the lower strata contain fossils of simpler life forms.
(Tendency toward increasing complexity over time.)
** When comparing fossils in undisturbed strata, fossils can be found in
upper strata which, although different from fossils in lower strata, resemble
those fossils. This suggests links between modern forms and older forms, as
well as divergent pathways from common ancestors.
adaptations--changes in organisms which make them better suited to their environment
Gene mutations can be caused by such agents as radiation and chemicals. When they occur in sex cells, the mutations can be passed on to the offspring; if they occur in other cells, they can be passed on to body cells only. The experiences an organism has during its lifetime can affect its offspring only if the genes in its own sex cells are changed by the experience.
biological adaptation -- changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment
Theory of Natural Selection
Darwin--(1859) Book--"On Origin of Species"
--stated his theory of Natural Selection
-- Natural selection and its evolutionary consequences provide a scientific explanation of the fossil record of ancient life-forms, as well as the molecular and structural similarities observed among the diverse species of living organisms.
(Theory of Natural Selection)
1. Overproduction -- Within a population more offspring are born than can possibly survive.
2. Competition -- since the number of individuals in a population tends to remain constant from generation to generation, a struggle for survival is suggested
3. Survival of the Fittest -- The individuals who survive are the ones best adapted to exist in their environment due to the possession of variations that maximize their fitness.
4. Reproduction -- Variations assist or hinder individuals in their struggle for survival.
The best adapted individuals survive and reproduce, passing on the favorable variations to their offspring.
5. Speciation -- as time and generations continue, adaptations are perpetuated in individuals and new species may evolve from a common ancestor.
adaptive variations--those variations which assist an organisms survival
(Weaknesses of Darwin's Theory)
1. Darwin didn't explain how variations arose.
2. He did not distinguish between hereditary and environmental variations.
3. Darwin believed that both environmental and hereditary variations were inherited.
Some Sources of Variation in Modern Natural Selection Theory
1. The genetic basis for variation within a species is provided by mutations and sexual reproduction. (crossing over and recombination)
2. Mutations are spontaneous and provide the raw material for evolution.
(Modern Natural Selection Theory)
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1. define the term evolution and recognize that current life forms have evolved
from earlier life forms.
2. recognize that evolution provides an explanation for the differences in structure,
function, and behavior among life forms.
3. recognize that radioactive dating has determined the approximate age of the earth
as 4.6 billion years.
4. define the term fossil and list examples of these.
5. state the law of superposition and relate it to the age and complexity of fossils found
in undisturbed horizontal rock layers (strata).
6. explain how observations of fossils in adjacent rock strata often support the theory
of evolution.
7. define the term adaptation.
8. explain how gene mutations may be increased in incidence.
9. recognize that gene mutations can only be passed on to the offspring if they occur
in an organism's sex cells.
10. define the term biological adaptation.
11. state Darwin's theory of natural selection and explain the following features in his
theory; overproduction, competition, variations, survival of the fittest, reproduction,
and speciation.
12. define the term adaptive variations.
13. explain some initial weaknesses of Darwin's theory.
14. compare the modern natural selection theory to that of Darwin.
15. state two sources of variation not recognized by Darwin.
16. explain the modern theory of natural selection.
17. explain why increased genetic diversity tends to enhance the survival of a species.
18. recognize that traits which are beneficial to an organism tend to enhance its survival,
while traits which are not beneficial tend to hurt its chances for survival.
19. explain the following examples of evolution in modern times in terms of the theory
of natural selection; peppered moth, insect resistance to insecticides, bacterial resistance
to antibiotics.
20. recognize that evolutionary factors operate on populations, not individual organisms.
21. define the term speciation.
22. describe the variety of pathways evolution may take.
23. recognize that the extinction of a species may occur when the environment changes and
the adaptive characteristics of an organism now longer support its survival.
24. recognize that extinction is common and that most of the organisms which have
appeared on this planet through its evolutionary history are now extinct.
25. recognize that the species is the fundamental unit of classification.
26. state the purpose of classification.
27. recognize that organisms are classified based on structural similarities and evolutionary
relationships.
28. realize that small differences between parents and offspring can accumulate over successive
generations so that descendants become very different from their ancestors.
29. recognize that the more similar two organisms DNA sequences, the more closely
related they are from an evolutionary standpoint.
30. recognize that 3 to 4 billion years ago it is thought that the first primitive life appeared on
the earth.
31. explain briefly the heterotroph hypothesis.
32. recognize that about 1 billion years ago, increasingly complex multicellular organisms
began to appear.
33. recognize that the great diversity of organisms is the result of billions of years of evolution
that has filled the available niches of the earth with life forms.
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--Chromosomes found in the nucleus carry the hereditary material -- DNA
DNA (deoxyribonucleic acid)
-- DNA controls cellular activity by influencing the production of enzymes.
(Structure of DNA Molecules)
DNA is a very long chain polymer made up of thousands of repeating units called nucleotides.
Nucleotide Unit is composed of a phosphate group, a pentose sugar, and a nitrogenous base.
The Nitrogenous Bases are; adenine (A) thymine (T) guanine (G) cytosine (C)
Watson and Crick (early 1950's)
-- determined the structure of the DNA molecule
** Consists of two chains of nucleotide units in a twisted ladder-like structure. (resembles a spiral staircase)
This spiral staircase is called an alpha helix. (37 degree turn)
-- The sides of the ladder are made up of alternating deoxyribose sugar -- phosphate group units.
-- The rungs of the ladder are made of 2 nitrogenous bases per rung linked together by a weak hydrogen bond.
-- Only 2 combinations of base pairs can form the rungs of the DNA molecule.
Adenine - Thymine (A-T)
Guanine - Cytosine (C-G)
** This specific matching up of the nitrogenous bases is called complementary base pairing.
** DNA is able to replicate itself.
[How does DNA form duplicates of itself during mitosis and meiosis?]
1. The double stranded DNA molecule unwinds and
unzips between the weak hydrogen bonds between
the nitrogenous base pairs.
2. Free nucleotides present in the nucleus attach
themselves by forming new hydrogen bonds with
the exposed bases in the single chain. The only
base which can reattach is the same type of base that was originally joined to it.
A view of DNA replication
(Usefulness of the Watson-Crick Model)
1. Explained how mitosis produces exact DNA copies
for each daughter cell -- thus the genetic information passes on unchanged.
2. Explained how DNA acts as a code directing the making of enzymes and other proteins by a cell, thus directing cellular activities.
(Directs the synthesis of RNA which makes proteins.)
RNA (ribonucleic acid)
** RNA is also a polymer formed by a sequence of nucleotides.
(How does RNA differ in structure from DNA?)
1. The RNA molecule is a SINGLE nucleotide
strand, not a double strand as in DNA.
2. The sugar molecule in RNA is RIBOSE --
not deoxyribose as in DNA.
3. The base URACIL (U) takes the place of thymine. (T)
[Synthesis of RNA]
-- The various types of RNA are made from the template (pattern) of the DNA molecule.
[Types of RNA]
1. mRNA (messenger RNA) made in nucleus
2. tRNA (transfer RNA) on the ribosomes
3. rRNA (ribosomal RNA) in the cytoplasm
[How are proteins synthesized from a DNA template? (model)]
1. DNA serves as a template for the synthesis of mRNA from RNA nucleotides in the nucleus.
transcription: transfer of the genetic message from DNA to mRNA
2. mRNA molecules carrying a specific code determined by the base sequence of the DNA template move from the nucleus to the cytoplasm.
3. Strands of mRNA carrying codons transcribed from DNA, move to the ribosomes in the cytoplasm.
codon: a triplet in a DNA molecule
triplet: grouping of three nitrogenous bases in DNA or RNA molecules
(each codon will code for a specific amino acid)
4. mRNA strands become associated with rRNA on
the ribosomes. (rRNA -- arranges date between mRNA and tRNA)
5. Different triplets of nitrogenous bases in tRNA
molecules pick up specific amino acids in the cytoplasm and carry them to
mRNA at the ribosomes. (tRNA -- I want aa.)
6. Amino acids are put into position on the ribosome with instructions from the
triplet codes of tRNA and mRNA.
7. With the aid of enzymes and ATP (energy), the
amino acids are bonded to form a polypeptide chain (protein) on the ribosome.
An overview of the entire protein synthesis (transcription and translation) process.
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1. recognize that DNA (deoxyribonucleic acid) controls cellular activity by influencing
the production of enzymes.
2. describe the structure of a nucleotide.
3. describe the structure of the DNA molecule.
4. explain what is meant by complementary base pairing.
5. explain how DNA is able to replicate itself during mitosis and meiosis.
6. correctly define the term template.
7. explain the usefulness of the Watson-Crick model of DNA.
8. define the term polymer and explain why DNA and RNA are polymers.
9. describe the structure of RNA and list three ways it differs in structure from DNA.
10. explain how proteins are synthesized from a DNA template.
11. define the terms transcription and translation.
12. explain the role of mRNA, rRNA, and tRNA in the process of protein synthesis.
13. correctly define the terms triplet, codon, and anticodon.
14. in a paragraph or two, explain how DNA, RNA, and proteins are able to determine
the individuality of an organism.
15. recognize that the work of a cell is carried out by the many different kinds of molecules
it assembles (especially its proteins).
16. recognize that proteins are long, folded molecules composed of up to 20 different kinds
of amino acids which interact to produce specific protein shapes.
17. recognize that enzymes and hormones are protein in nature.
18. recognize that the specific shape of a protein usually determines its function.
19. realize that offspring resemble their parents because they inherit similar genes that code
for the production of proteins that form similar structures and perform similar functions.
20. explain in a paragraph how cell functions are regulated.
21. explain why the body cells of an organism can be very different from each other, even
though they have the same genetic makeup.
22. explain what is meant by cloning and list some uses of this.
23. describe the process of genetic engineering and list five uses for this procedure.
24. explain what restriction enzymes are and how they are used.
25. recognize that inserting, deleting, or altering DNA segments can alter genes and that
this alteration may be passed on to every cell that develops from the altered cell.
26. explain what the genetic mapping is.
27. explain what the human genome project is and some potential advantages and
disadvantages of this work.
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1. recognize that DNA (deoxyribonucleic acid) controls cellular activity by influencing
the production of enzymes.
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2. describe the structure of a nucleotide.
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3. describe the structure of the DNA molecule.
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4. explain what is meant by complementary base pairing.
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5. explain how DNA is able to replicate itself during mitosis and meiosis.
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6. correctly define the term template.
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7. explain the usefulness of the Watson-Crick model of DNA.
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8. define the term polymer and explain why DNA and RNA are polymers.
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9. describe the structure of RNA and list three ways it differs in structure from DNA.
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10. explain how proteins are synthesized from a DNA template.
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11. define the terms transcription and translation.
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12. explain the role of mRNA, rRNA, and tRNA in the process of protein synthesis.
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13. correctly define the terms triplet, codon, and anticodon.
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14. in a paragraph or two, explain how DNA, RNA, and proteins are able to determine the individuality of an organism.
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15. recognize that the work of a cell is carried out by the many different kinds of molecules
it assembles (especially its proteins).
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16. recognize that proteins are long, folded molecules composed of up to 20 different kinds
of amino acids which interact to produce specific protein shapes.
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17. recognize that enzymes and hormones are protein in nature.
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18. recognize that the specific shape of a protein usually determines its function.
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19. realize that offspring resemble their parents because they inherit similar genes that code
for the production of proteins that form similar structures and perform similar functions.
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20. explain in a paragraph how cell functions are regulated.
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21. explain why the body cells of an organism can be very different from each other, even
though they have the same genetic makeup.
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22. explain what is meant by cloning and list some uses of this.
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23. describe the process of genetic engineering and list five uses for this procedure.
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24. explain what restriction enzymes are and how they are used.
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25. recognize that inserting, deleting, or altering DNA segments can alter genes and that
this alteration may be passed on to every cell that develops from the altered cell.
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26. explain what the genetic mapping is.
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27. explain what the human genome project is and some potential advantages and
disadvantages of this work.
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--Chromosomes found in the nucleus carry the hereditary material -- DNA
DNA (deoxyribonucleic acid)
-- DNA controls cellular activity by influencing the production of enzymes.
(Structure of DNA Molecules)
DNA is a very long chain polymer made up of thousands of repeating units called nucleotides.
Nucleotide Unit is composed of a phosphate group, a pentose sugar, and a nitrogenous base.
The Nitrogenous Bases are; adenine (A) thymine (T) guanine (G) cytosine (C)
Watson and Crick (early 1950's)
-- determined the structure of the DNA molecule
** Consists of two chains of nucleotide units in a twisted ladder-like structure. (resembles a spiral staircase)
This spiral staircase is called an alpha helix. (37 degree turn)
-- The sides of the ladder are made up of alternating deoxyribose sugar -- phosphate group units.
-- The rungs of the ladder are made of 2 nitrogenous bases per rung linked together by a weak hydrogen bond.
-- Only 2 combinations of base pairs can form the rungs of the DNA molecule.
Adenine - Thymine (A-T)
Guanine - Cytosine (C-G)
** This specific matching up of the nitrogenous bases is called complementary base pairing.
** DNA is able to replicate itself.
[How does DNA form duplicates of itself during mitosis and meiosis?]
1. The double stranded DNA molecule unwinds and
unzips between the weak hydrogen bonds between
the nitrogenous base pairs.
2. Free nucleotides present in the nucleus attach
themselves by forming new hydrogen bonds with
the exposed bases in the single chain. The only
base which can reattach is the same type of base that was originally joined to it.
A view of DNA replication
(Usefulness of the Watson-Crick Model)
1. Explained how mitosis produces exact DNA copies
for each daughter cell -- thus the genetic information passes on unchanged.
2. Explained how DNA acts as a code directing the making of enzymes and other proteins by a cell, thus directing cellular activities.
(Directs the synthesis of RNA which makes proteins.)
RNA (ribonucleic acid)
** RNA is also a polymer formed by a sequence of nucleotides.
(How does RNA differ in structure from DNA?)
1. The RNA molecule is a SINGLE nucleotide
strand, not a double strand as in DNA.
2. The sugar molecule in RNA is RIBOSE --
not deoxyribose as in DNA.
3. The base URACIL (U) takes the place of thymine. (T)
[Synthesis of RNA]
-- The various types of RNA are made from the template (pattern) of the DNA molecule.
[Types of RNA]
1. mRNA (messenger RNA) made in nucleus
2. tRNA (transfer RNA) on the ribosomes
3. rRNA (ribosomal RNA) in the cytoplasm
[How are proteins synthesized from a DNA template? (model)]
1. DNA serves as a template for the synthesis of mRNA from RNA nucleotides in the nucleus.
transcription: transfer of the genetic message from DNA to mRNA
2. mRNA molecules carrying a specific code determined by the base sequence of the DNA template move from the nucleus to the cytoplasm.
3. Strands of mRNA carrying codons transcribed from DNA, move to the ribosomes in the cytoplasm.
codon: a triplet in a DNA molecule
triplet: grouping of three nitrogenous bases in DNA or RNA molecules
(each codon will code for a specific amino acid)
4. mRNA strands become associated with rRNA on
the ribosomes. (rRNA -- arranges date between mRNA and tRNA)
5. Different triplets of nitrogenous bases in tRNA
molecules pick up specific amino acids in the cytoplasm and carry them to
mRNA at the ribosomes. (tRNA -- I want aa.)
6. Amino acids are put into position on the ribosome with instructions from the
triplet codes of tRNA and mRNA.
7. With the aid of enzymes and ATP (energy), the
amino acids are bonded to form a polypeptide chain (protein) on the ribosome.
An overview of the entire protein synthesis (transcription and translation) process.
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8. define the term polymer and explain why DNA and RNA are polymers.
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9. describe the structure of RNA and list three ways it differs in structure from DNA.
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11. define the terms transcription and translation.
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12. explain the role of mRNA, rRNA, and tRNA in the process of protein synthesis.
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14. in a paragraph or two, explain how DNA, RNA, and proteins are able to determine the individuality of an organism.
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16. recognize that proteins are long, folded molecules composed of up to 20 different kinds
of amino acids which interact to produce specific protein shapes.
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25. recognize that inserting, deleting, or altering DNA segments can alter genes and that
this alteration may be passed on to every cell that develops from the altered cell.
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Please note that these notes include discussion of basic genetics terminology but work including the manipulation involved in basic crosses is not included.
Basic Genetics -- Mendel (1866)
** Mendel developed some basic principles of heredity without any knowledge
of genes or chromosomes. His principles of dominance, segregation, and
independent assortment were established through the mathematical analysis of
large numbers of offspring produced by crossing pea plants.
** As a result of analyzing specific mathematical ratios associated with certain characteristics in the offspring, Mendel proposed that characteristics were inherited as the result of the transmission of hereditary factors.
** Mendel observed contrasting characters in pea plants in his work.
(Why was Mendel successful with the pea?)
1. Used pure breeding, contrasting varieties.
2. Studied characteristics one at a time for many generations.
3. Used statisitics in analyzing his results.
4. Obtained large numbers of offspring.
5. Chose pea plants which normally self-fertilize.
** Mendel had no knowledge of genes or chromosomes.
genes: factors that control organism traits -- the part of the DNA molecule containing the genetic code
Every organism requires a set of coded instructions for specifying its traits. For offspring to resemble their parents, their must be a reliable way to transfer hereditary information from one generation to the next.
Each gene carries a separate piece of information. An inherited trait of an individual can be determined by one or by many genes, and a single gene can influence more than one cell.
Each human cell contains thousands of different genes.
alleles: different forms of a gene associated with a particular characteristic
(ex. height -- tallness -- shortness)
Each gene may have one or more forms called alleles. The alleles determine how each gene is expressed.
chromosomes: hereditary units of an organism
locus: particular point where a certain gene is found on a chromosome
homologous chromosomes: pair of associated chromosomes -- each
chromosome in the pair is called a homologue
** Alleles are located in the same position or locus on homologous chromosomes.
In asexually reproducing organisms, all the genes come from a single parent. These genes are normally identical to the parent. (clone)
Sexually reproducing organisms normally receive half their genetic information from the Mother's egg and half their genetic information from their Father's sperm. Sexually reproduced offspring resemble but are not identical to their parents.
** The significance of Mendel's work was not immediately recognized.
** Mendel's hereditary factors, now called genes, exist at definite loci in a
linear fashion on chromosomes. Two genes associated with a specific characteristic are known as alleles and are located on homologous chromosomes. The gene-chromosome theory provides the mechanism to account for the hereditary patterns which Mendel observed.
homozygous (pure) -- an individual with two of the same alleles on homologous chromosomes
heterozygous: (hybrid) -- an individual with contrasting alleles for the same trait on homologous chromosomes
parental generation (P) -- the two original organisms being crossed
first filial generation -- the first generation of offspring from the parents
second filial generation -- generation of offspring arising from the first filial generation
[Some Major Genetic Concepts]
1. Law of Dominance (Mendel)
-- a pattern of heredity in which only one gene of an allelic pair is expressed
-- thus in the heterozygous condition, one allele of a gene may express itself and mask the presence of the other allele
ex. red flowering X white flowering-->red flowering peas
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dominant trait: the trait or allele that is expressed
recessive trait: the trait or allele will not be expressed if there is a dominant allele present
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1. recognize that Mendel developed his laws of heredity without any prior
knowledge concerning genes or chromosomes.
2. list at least five reasons for Mendel's success working with pea plants.
3. recognize that every organism has coded instructions for specifying its traits and
that DNA provides a reliable way for transferring hereditary information from one
generation to the next.
4. recognize that each gene carries a separate piece of information.
5. recognize that the inherited trait of an individual can be determined by one or by many
genes, and that one gene can influence more than one cell.
6. recognize that each human cell contains thousands of genes.
7. correctly define the following terms; gene, allele, chromosome, locus, and homologous
chromosomes.
8. recognize that alleles are located on the same position on homologous chromosomes.
9. recognize that in asexually reproducing organisms, all the genes come from a single
parent and are identical to those of the parent.
10. recognize that sexually reproducing organisms receive half their genetic information from
their Mother's egg and half from their Father's sperm.
11. recognize that sexually reproduced offspring usually resemble, but are not identical to
their parents.
12. define the following terms and correctly use them in reference to genetic crosses;
homozygous, heterozygous (hybrid), parental generation, first filial generation, and
second filial generation.
13. define the terms progeny and sibling.
14. define the following terms and correctly use them in reference to genetic crosses;
phenotype and genotype.
15. state Mendel's three Laws of Heredity and correctly explain each.
16. list two examples of intermediate inheritance.
17. list two examples of codominance.
18. correctly complete genetic crosses/Punnett squares involving the Law of Dominance,
incomplete dominance, or codominance.
19. define the term gene linkage and list an example of this in humans.
20. define the term crossing over and explain how it leads to genetic variability in
sexually produced offspring.
21. explain what is meant by a karyotype and list some examples of its usefulness.
22. explain how sex is determined in the genetic makeup of humans.
23. explain why the male determines the sex of a human baby.
24. define the term mutation.
25. explain why only mutations in gametes may be passed on to the offspring.
26. explain the difference between a chromosomal alteration and a gene mutation.
27. define the following terms correctly; disjunction, nondisjunction, polyploidy,
and mutagenic agent.
28. list some examples of mutagenic agents.
29. recognize that the adaptive value of a gene mutation is dependent upon the nature of the
mutation and the type of environment in which the organism interacts.
30. list three examples of the interaction of the environment with genes in the expression of
inherited traits.
31. explain the difference between the following types of selective breeding; artificial selection,
inbreeding, hybridization, vegetative propagation, and recombinant DNA technology.
32. explain the difference between the following changes in chromosome structure;
translocation, addition, deletion, and inversion.
33. recognize that the mapping of the genetic instructions in cells makes it possible to detect,
and perhaps correct, defective genes that lead to poor health.
34. recognize that substances from genetically engineered organisms may reduce the costs
and side effects of replacing costly body chemicals.
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Homeostasis in an organism is constantly threatened. Failure to respond effectively can result in disease or death.
Viruses, bacteria, fungi, and other parasites may infect plants and animals and interfere with normal life functions.
Immune response--defensive reaction of the body to foreign substances or organisms
The immune system also protects against some cancer cells which may arise in the body.
Natural Killer Cells destroy the bodies own infected cells, especially those containing viruses. They may attack cells that might form tumors.
antigens--foreign substances or organisms which stimulate the body to make antibodies
antibodies--specific plasma proteins which render harmless or destroy a specific antigen produced by certain white blood cells (ex. lymphocytes)
An antibody has a specific shape which only allows it to attack a specific antigen.
Other white blood cells mark antigens for attack by antibodies or attack and engulf the antigen. (phagocytes)
immunity--the accumulation of specific antibodies in the plasma of the blood enabling the individual to resist specific diseases
Ways of acquiring immunity:
1. Active immunity--the individual either possesses or forms his or her own antibodies within his or her own body
** The antigen-antibody reaction occurs within the body in response to either contact with the disease-causing organisms or their products, or by receiving a vaccination.
Vaccinations use weakened microbes or parts of microbes to stimulate the immune system to react. (primary immune response) This reaction stimulates the body to fight subsequent invasions by the same microbes. (secondary immune response)
2. Passive immunity--a temporary form of immunity produced by the introduction of antibodies into an individual from another organism "Let the others do the work" This immunity is of short duration.
allergy--an extreme body reaction to certain foreign proteins (antigen-antibody rx.)
Some allergic reactions are caused by the body's immune responses to usually harmless environmental substances.
autoimmune diseases -- the immune system attacks some of the body's own cells
exs. Crohn's disease, myasthenia gravis, multiple sclerosis, lupus, fibromyalgia
Antibodies formed in response to these substances may cause inflammations and/or result in the release of a chemical substance called histamine. The histamine causes the allergic response.
antihistamine--stops this allergic reaction
AIDS (Acquired immune deficiency syndrome)
-- a viral disease which damages the immune system
-- this damage leaves the body unable to cope with numerous infectious agents and cancerous cells
Our increased knowledge of immunity has resulted in the ability to type blood and transplant organs.
Major lymph vessels have lymph nodes which contain phagocytic white blood cells which filter bacteria and dead cells from the lymph.
[Some other causes of disease include]
1. inheritance
2. toxic substances
3. poor nutrition
4. organ malfunction
5. poor personal behaviors and choices
cancer -- results from gene mutations in cells which cause uncontrolled cell division
** Exposure of cells to certain chemicals and radiation increases mutations and thus increases the chances of cancer.
Biological research (such as the human genome project) generates knowledge used to design ways of diagnosing, preventing, treating, controlling, and curing diseases of plants and animals.
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1. define disease as a failure of homeostasis and list examples of this.
2. recognize that viruses, bacteria, fungi. and other organisms may invade other plants
and animals interfering with their homeostasis.
3. explain what is meant by the immune response.
4. state the function of natural killer cells.
5. define the term antigen.
6. define the term antibody.
7. explain how phagocytes and lymphocytes assist in the immune function.
8. recognize that some white blood cells may mark antigens for attack by other
white blood cells or antibodies.
9. recognize that antibodies have specific shapes which allow them to attack specific
antigens.
10. explain what is meant by immunity.
11. explain the difference between active and passive immunity and list some ways of getting
each of these.
12. explain how receiving a vaccination or recovery from a disease may produce a primary
and secondary immune response.
13. explain what an allergy is.
14. explain the difference between a histamine and an antihistamine.
15. explain what is meant by autoimmune diseases and list some examples of these.
16. discuss what AIDS is and explain how it destroys the immune system.
17. relate our knowledge of immunity to tissue transplantation and blood typing.
18. explain the role of lymph nodes in the immune process.
19. list 5 other causes of disease besides infections or parasitic attacks and list
some examples of each of these causes.
20. explain what cancer is and how it interferes with homeostasis.
21. recognize that exposure of cells to certain chemicals and radiation increases the
chance of having a mutation and getting cancer.
22. recognize that biological research may generate knowledge used to prevent,
diagnose, treat, control, and cure diseases of plants and animals.
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| Meiosis and Sexual Reproduction and Development |
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Gametogenesis: the formation of gametes (eggs and sperms)
Chromosomes exist in pairs in body cells.
Each species has a characteristic number of chromosomes.
homologous chromosomes: the 2 members of a pair of chromosomes
-- contain genes for the same traits
diploid number: the number of chromosomes found in the double set of chromosomes found in all body cells (2n)
** Eggs and sperm contain only 1/2 the diploid number of chromosomes.
haploid (monoploid) number: 1/2 the diploid number of chromosomes -- found
in the egg and sperm cells of a species
gametes: eggs or sperm
gonads: specialized organs in higher animals where the gametes are made
ovaries: female gonads
testes: male gonads
Meiosis: process which involves a 1/2 reduction division of the chromosome number
-- The chromosome numbers of a cell produced by meiosis are reduced by 1/2
-- haploid nuclei are formed which contain only one chromosome of the original homologous pair.
** Meiosis ONLY occurs in the gamete producing cells of the gonads.
** The diploid chromosome number of a species is maintained from one
generation to the next through the processes of MEIOSIS and FERTILIZATION.
[Process of Meiosis]
-- formation of sex cells occurs
-- involves two divisions
-- the first is a reduction division -- the second a mitotic division
(First Meiotic Division)
1. Each single stranded chromosome is replicated during the non dividing resting period
-- this results in double stranded homologous chromosomes being formed.
2. Chromosomes shorten and thicken with the spindle apparatus being formed.
3. Homologous chromosomes pair up side by side in a
double line at the equator. (center of the cell)
These homologous chromosome pairs are called tetrads.
It is here that synapsis and crossing over occurs.
synapsis: the meeting of two homologous chromosome pairs
tetrads: the two pairs of homologous chromosomes
crossing over: the exchange of chromosome pieces in the tetrad during crossing over
Crossing over increases the variability of the offspring. This is why the
offspring of sexual reproduction show many variations.
4. Homologous pairs of chromosomes separate and move toward opposite poles of the cell.
disjunction: the separation of the homologous chromosome pairs during the first division of meiosis
nondisjunction: the failure of homologous chromosomes to separate
** Down's syndrome (Mongolian idiocy) results from
the nondisjunction of chromosome 21 -- this results in the afflicted individual having an extra 21st chromosome. (an extra chromosome overall as well)
** Changes in the chromosome number of an individual usually results from nondisjunction.
polyploidy: having an entire extra set of chromosomes
Will result in the 3n or 4n number of chromosomes.
5. Cytoplasmic division of the cell occurs -- ends the first stage of meiosis (reduction division)
-- each daughter cell contains the diploid number of chromosomes.
(Second Meiotic Division)
-- similar to mitosis but no chromosome replication occurs
-- the diploid number of chromosomes is reduced to
the monoploid number in this division
1. Spindle apparatus is synthesized with homologous
chromosomes lining up at the equator.
2. Centromeres are replicated and each single stranded chromosome separates
and moves toward opposite poles of the cell.
3. Cytoplasmic division of the cell occurs.
(Results of Meiosis)
1. The diploid number (2n) of chromosomes is reduced by 1/2 to the monoploid number. (n)
2. Specialized reproductive cells (eggs and sperms) are formed.
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3. The distribution of homologous chromosomes is random -- thus variations frequently occur.
** Variations rarely occur in MITOSIS.
** Variations often occur in MEIOSIS because of independent assortment and crossing over
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Know the steps of gametogenesis and how the gametes form a zygote
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Know the steps of Meiosis I and Meiosis II
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Recognize the steps of Meiosis I and Meiosis II from different pictures of each step
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Be able to explain crossing over and during what phase it occurs
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Know the problems that can occur with Meiosis ie: Down's Syndrome
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