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72 Cards in this Set
- Front
- Back
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Law of Segregation |
for each trait, every individual must have two determiners called alleles (half from dad, half from mom) |
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Law of Independent Assortment |
each trait is inherited independently from each other (Mendel crossed 2 characteristics of pea plants at a time: DIHYBRID CROSS) |
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Golden Phenotypic Ratio |
9:3:3:1 (D/D: equal : d/d) |
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Codominance example |
both phenotypes are expressed
Example: Fur colour in cows: white, red-brown and ROAN |
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Codominance + Multiple Alleles |
example of human blood types - 3 alleles for each blood type gene - AB are codominant - both present = both expressed in phenotype - antigens + antibodies can be fatal |
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example of codominance |
Sickle cell anemia - normal (HbAHbA) - sickle cell trait (HbAHbs) - sickle cell disease (HbSHbS) |
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Incomplete Dominance Example |
two traits get blended example: Red+ white trait in snapdragon flowers = pink |
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Sex Linked Inheritance |
- genes for a trait are linked to the X chromosome Examples: hemophilia, colourblindness |
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Hemophilia |
- disease caused by a missing protein in the blood; blood doesn't clot properly - die from excessive bleeding - NORMAL IS DOMINANT - alleles XH = normal Xh = hemophiliac - carriers do not exhibit the disease |
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Colourblindness |
- NORMAL IS DOMINANT - alleles XN = normal Xn = colourblind |
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Mutation |
any change in genes (can be harmful, beneficial or have no effect) |
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Genetic Abnormalities (5) |
1. point mutation 2. deletion 3. addition 4. translocation 5. changes in number/kind of chromosome |
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Point Mutation |
- a mistake in a small section of the gene - usually only one chemical is incorrect |
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Deletion |
- lose part of a gene |
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Addition |
- an extra section of DNA is added to the gene |
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Translocation |
- sections of the gene/chromosome get mixed up |
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Aneuploidy |
- condition resulting from non-disjunction of homologous chromosomes during Meiosis I |
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Changes in Number/Kind of Chromosome (6) |
1. Down Syndrome 2. Klinefelter Syndrome 3. Turner Syndrome 4. Metafemale 5. Jacob (Supermale) Sydrome 6. Cri du Chat Syndrome |
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Down Syndrome |
- extra copy of chromosome 21 (2 from egg, third from sperm) - mentally challenged, wide rounded face, enlarged tongue, usually sterile - increased risk as female is older (1 in 800 < 40 years vs 1 in 60 > 40 years) |
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Klinefelter Syndrome |
- 1 in 500-2000 - genotype: XXY - males - mentally challenged, undeveloped testes, breasts development, sterile |
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Turner Syndrome |
- 1 in 2500 - 10000 - genotype: XO - females - shorter than average, webbed neck, broad chested, may be mentally challenged, sterile, don't undergo puberty/menstruation |
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Metafemale |
- 1 in 1000-2000 - genotype XXX - females - some learning disabilities, no physical abnormalities, menstrual irregularities, early menopause |
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Jacob (Supermale) Syndrome |
- 1 in 1000 - genotype XYY - normal male features, not sterile, usually taller than average, persistent acne, barely normal intelligence, associated with criminally aggressive convicts |
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Cri Du Chat Syndrome |
- part of chromosome 5 missing - small head, malformed face and body, mentally challenged, "meow" like a kitten |
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Polygenic Inheritance |
- occurs when 2 or more sets of genes affect the same trait in an additive fashion - results in a continuous variation of phenotypes between the extremes + distribution of these phenotypes resembling a bell-shaped curve example: height in humans and skin colour in humans |
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Recominants |
- offspring in dihybrid crosses that inherit a new combination of characteristics from the parents |
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Recombination |
- the exchange of alleles between homologous chromosomes as a result of crossing over - a reassortment of genes or characteristics into different combinations from those of the parents |
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Unlinked genes |
- unlinked genes are located on different types of chromosome, so when homologous chromosomes pair up in meiosis, they are on different pairs |
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Bivalents |
- pairs of homologues |
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Bivalents and the premise behind Independent Assortment of Unlinked Genes |
- oriented randomly on the equator; thus the way each allele of a gene moves towards the pole is unaffected by the way other alleles of unlinked genes move |
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Independent Assortment of Unlinked Genes |
- allows the recombination of unlinked genes - combinations of alleles inherited from a parent are broken up + new combinations can then be formed by random fertilization |
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Gene Linkage (6 points) |
- pairs of genes that are located on the same type of chromosome - combination of genes that tend to inherited together - these pairs of genes DON'T follow the Law of Independent Assortment (9:3:3:1 ratio isn't found) - more offspring than expected with the parental character combos - more offspring resembling Parental phenotypes - the closer the linked genes are to each other on the chromosome, crossing over to form recombinants is less likely |
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Lamarck (2 laws) |
- idea of change through time - Law of Use and Disuse - body parts that were used became more developed than those that were not (the opposite holds true to the point of complete disappearance) - Law of Inheritance of Acquired Characteristics - assumed that organisms could pass on the traits they had gained over one lifetime (pass on acquired physical development to offspring) |
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Darwin (2 observations) |
- species changed over time - studied data from voyage to Galapagos - noticed struggle for existence among all life forms (space, food, shelter) - noticed that populations tend increase faster than food supply (results: overcrowding, poverty, war, famine, disease) - proposed a theory of NATURAL SELECTION with Alfred Wallace ("survival of the fittest") |
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Lamarck + Giraffes |
- giraffes evolved from short-necked ancestors - ancestors needed to reach leaves from tall trees; lifetime of stretching to reach leaves resulted in long necks - offspring would inherit the long necks of their parents |
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Darwin + Giraffes |
- giraffes evolved from long-, medium- and short-necked giraffes - scare food supply - tall-necked giraffes were better at reaching leaves on tall trees; short necked ones couldn't and died - tall-necked giraffes survived to reproduce and resulted in the long-necked giraffes of today |
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Evidence Since Darwin (7) |
1. Fossil Records 2. Age of the Earth 3. Comparative Anatomy 4. Comparative Embryology 5. Comparative Biochemistry 6. Speciation 7. Cladistics |
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Fossil |
- any evidence of life in prehistoric past - can be: actual remains of organisms, impressions, carbon residues, tracks (footprints), eggs or even mineralized + hardened excrement |
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Fossil Records (5) |
- provide evidence of time + place (jigsaw puzzle) - minimal fossil records - allow scientists (paleontologists) to investigate evolutionary trends - show that some organisms exist over time (intermediate species) - fossil record is now more complete than in Darwin's time |
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Why are there Minimal Fossil Records? |
- aquatic organisms are more often fossilized (ie. sediments from rivers + streams pile in layers) - ocean bottoms don't erode - land does - land environment is often dry - decomposition of organisms is quite common |
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Age of the Earth |
- earth is approx. 4.5 billion years old (thought to only be a few thousands years old in Darwin's time --> not enough time for his theory to have occurred) - relative + radioactive dating - by comparing the amts of radioactive to non-radioactive elements + half life, one can determine the age of a sample |
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Relative Dating |
- technique to determine age of fossils relative to other fossils - actual age is not possible |
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Radioactive Dating |
- using the rate of decay/break down of radioactive elements to non-radioactive elements to determine the age of fossils
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Half-Life + Example |
- length of time needed for half of the radioactive atoms in a sample to decay example: for older samples (>100K years) Uranium-238 ---> Lead 206 (hl: 4.5 billion years) Potassium-40 --> Argon-40 (hl: 1.3 billion years) for once living samples (bones)/ much younger samples Carbon-14 ---> Nitrogen-14 half life: 5770 years |
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Comparative Anatomy |
- study of body structures - organisms with a common ancestry often have similar structures (homologous, analogous, vestigial) |
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Homologous Structures + Example |
- structures (ie. organ, bones, tissue type, etc) which are found in different organisms + have the same origin but different functions example: forelimbs of vertebrates - arm of human, wings of birds/bats, pectoral fins of whales, etc |
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Analogous Structures + Example |
- structures with similar functions but have different evolutionary origins example: wings of insects and bats |
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Vestigial Structures + Example |
- structures that are underdeveloped + non-functional example: in humans: tailbone, appendix, ear muscles, wisdom tooth, body hair, embryonic gills |
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Comparative Embryology + Example |
- sharing of similar embryonic stages example: gills + tailbone in humans |
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Comparative Biochemistry |
- DNA can be used to determine the degrees of relatedness in organisms - the more DNA two species have in common, the more closely related they are |
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Speciation + Species (3) |
- the development of new species - species = a group of organisms capable of interbreeding in a natural environment and producing viable offspring (share a common gene pool) 1. Preadaptations 2. Kinds of Selection 3. Pressure on Populations |
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Preadaptations + Example |
- adaptive traits that existed in an organism before they are of value as a result of random mutation - not caused by changed factor in the environment (they were already in existence as part of the diversity in species) example: Peppered moths (Kettlewell's exp't) - dark mutation was a preadaptation - mutation existed before it had a value for survival |
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Kinds of Selection (5) |
1. Directional Selection 2. Stabilizing Selection 3. Disruptive Selection 4. Artificial Selection 5. Accidental Selection |
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Directional Selection + 2 examples |
- involves changes that take place when a population shows a steady trend through time - trend can be a deviation of a trait (increase in size of horses through time) - or a disappearance of a trait (toes of mammals and hoofed animals) |
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Stabilizing Selection + 2 examples |
- occurs when organisms that represent extreme departures from the normal are removed from population examples: - change in animal's coat colour --> eliminated from population because it is noticeable to predators - bird's song/behaviour --> departure from the "normal" song; unable to attract mate |
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Disruptive Selection + Example |
- aka "Divergence" - "abnormal" features that have a high survival value are selected --> intermediate types are selected against example: deer mouse + white footed mouse - thought to have been a single species; two populations came as a result of exploration of different habitats - deer mouse: open meadows - white-footed mouse: nearby wooded areas - selection favoured the forms that were best suited to each of the new habitats --> intermediate types were eliminated b/c they were unable to compete with better adapted forms - breeding encounters between the two adapted forms became less frequent |
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Artificial Selection + 4 examples |
- organisms with useful traits were selected for human needs + desires - controlled selection through controlled breeding produced a wide range of useful plants and animals examples - cat and dog breeds - cattle - put on weight fast - plants - resist pests; beauty - chickens - weight gain; egg production |
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Accidental Selection + Example |
- random mutation that renders an organism more fit for a certain environment even though they have yet to exist example: antibiotic - resistant bacteria "superbugs" DDT resistant pests |
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Pressure on Populations (2) |
1. Adaptive Radiation 2. Convergent Evolution |
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Adaptive Radiation + Example |
- aka Divergent Evolution - a # of different species diverge from a common ancestral form - due to populations being exposed to different selection pressures = become less + less alike; intermediate forms drop out + become separate species - more likely to occur if: - large #s of offspring produced; more gene combos (insects) - short interval between generations (insects) Example: Darwin's finches; all 14 species evolved from a single ancestral species |
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Directional Selection (Graph) |
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Stabilizing Selection |
- ends/abnormalities are eliminated |
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Disruptive Selection |
- normal is gone; intermediate types unable to compete with more evolved forms |
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Reproductive Isolation |
- agent for the formation of new species when populations are isolated from interbreeding - main categories: premating factors + postmating factors |
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Premating Factors |
- prevent mating from taking place - geographic barriers, habitat preference, behavioural differences, mating periods, body size + structure, natural disasters |
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Geographical Barriers + Example |
- population of a single species isolated from each other by mountains, rivers, canyons, roads, continental drift, etc - example: Kaibab + Abert squirrels of Grand Canyon |
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Habitat Preference Example |
deer mouse + white footed mouse |
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Behavioural Difference |
- courtship of displays/songs to attract mate (performed in precise manner) |
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Mating Periods |
- breeding/fertile periods of organisms |
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Body Size + Structure Example |
Mouse + Elephant |
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Natural Disasters |
- forest fires, earthquakes, hurricanes, etc can wipe out entire populations |
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Post Mating Factors + 2 Examples |
- reduce the chances for survival of offspring once mating has taken place - example: mules are sterile - example: death of offspring or fertilized ovum during development |
