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| Term | Definition |
|---|---|
| Genetic variability | - genetic characteristics in a population to vary from one another. -Mutations create variation -other type of selection can maintain genetic variability in a population (Sickle cell anemia) -Heterozygote advantage -Frequency dependent selection |
| Polygenic traits are: | -Often a genetic & environmental component -Skin color -height -fingerprint ridges contact -Skin exposure -nutrition -amniotic sac |
| Polygenic traits | -whose phenotype is influenced by more than one gene -No discrete traits like Mandel's traits (height, weight) -Quantitative Traits: continuously varying traits |
| A gene "for" | - 1 gene doesn't code for a behavior -1 gene codes for 1 protein (or RNA molecule) -A change in 1 protein can alter numerous gene environment interactions & produce detectable difference in phenotype. |
| Australopithecines | -transition to living on the ground resulted in bipedalism -freeing up the hands |
| language gene | -FOXP2 -encodes transcription factor, influences gene expression in parts of brain involved in language. |
| Sympatric model | Species evolve from a parent species side by side without physical separation |
| allopatric model | The hypothesis that speciation occurs when populations become geographically isolated and diverge because selection and drift act on them independently |
| reproductive isolation mechanisms | factors that contribute to individuals being isolated from one another, promotes speciation. -Prezygotic & postzygotic |
| Speciation | Formation of new species |
| positive selection | natural selection that increases the frequency of a favorable allele |
| neutral selection | differences in DNA sequence that do not confer a selective advantage or disadvantage |
| gene duplication | one chromosome may have 2 copies of a gene or genes due to unequal crossing over |
| Polymorphism | The coexistence of two or more distinct forms in the same population. -neutral, deleterious, adaptive |
| phylogenetics | study of evolutionary relationships -parsimony |
| Paternity tests | DNA profiling typically uses repetitive sequences that vary a lot -Microsatellites: <6 bp repeats also called short tandem repeats STRs -Minisatellites: >5 bp repeat |
| Crisper/cas9 | -abnormal gene repaired through editing the mutation, which returns the gene to its normal function -currently in development -moratorium on use in germline cells |
| Somatic gene therapy | -normal gene inserted into non specific location within the genome to replace a nonfunctional gene -doesn't work for gain of function mutations |
| Protein replacement therapy | -some single gene diseases can be treated by ingestion or injection of gene product. -can access tissue or cells where normal gene product is needed. Diabetes: insulin Hemophilia: clotting factors |
| Cystic fibrosis gene | -positional cloning used to identify gene -pedigree analysis identifies an RFLP closely linked gene. -DNA sequencing used to explore neighboring genes. |
| Cystic fibrosis | -recessive autosomal -hereditary disease affecting the exocrine mucus glands of the lungs, liver, pancreas, & intestine. -Causes progressive disability due to multisystem failure -CF caused by a mutation in the gene for cystic fibrosis transmembrane conductance regulatory |
| Frgile X syndrome | -X linked dominant mutation -caused by unstable trinucleotide repeat(CGGN) -significant mental impairment -facial & behavioral abnormalities -Normal FMR: 1 alleles, CGG normal repeats 6-59 -Premature: repeats 60-200, can get fragile X, unstable, tends to expand. -Mutant: repeats 200+, methylation: gene gets turned off, will get fragile X Why is it dominant? X inactivation results in some cells having an active allele & others having an inactive allele. |
| Chronic granulomatous disease | -children bald at defending self with immune system, very vulnerable to viral infections, -Due to mutation in X- linked recessive gene gp90 -certain cell of immune sys. have difficulty forming reactive O2 compounds used to kill certain cell ingested pathogens. -Males only need 1 to have disease -Females need 2 |
| PCR test | -blood test to find and analyze DNA and RNA in viruses, diagnose genetic diseases, and do DNA fingerprinting. -determine repeat # by separating products by gel electrophoresis |
| Huntington's disease | -dominant autosomal -hereditary disease that results in gradual loss of neurons central region of the brain(loss of coordinated movement). disease does not develop until after reproductive age. -Hunting protein: identified, role unknown -Mutant protein: gain of function mutations |
| disruptive selection | -Diversifying selection- splits bell curve -Darwin's Finches: small seed & large seeds but no intermediate size seeds lead to selection for 2 beak sizes. -Monitor lizard examples: small lizards can hide for predatory birds, large lizards can fight them off. |
| stabilizing selection | -narrows bell curve -ex. human birth weight -size of birth canal limited by size of the opening in the pelvic bone -small babies at disadvantage for nutrients/ developmental reasons. -Large babies at disadvantage because cranium might get stuck. |
| Directional selection | -occurs when natural selection favors one of the extreme variations of a trait -Directional selection against one allele can remove it from population -Light allele in polluted habitat: less effective (light allele can hide from selection in heterozygotes). -Light allele in unpolluted habitat: more effective (dark allele always exposed). -shifts bell curve right to left (ex. Giraffes neck gets longer to reach higher leaves) |
| Marine Isopods | -Alpha: large, excludes other males from sponge -Beta: medium sized, when encountered by alpha, pretends to be a female. Sneak matings from real females. -Gamma: Tiny, alphas grow gammas out of sponge, gammas sneak matings from females. |
| Perissodus microlepis | -Prey learns to look to right when being vigilant to attack from more common left-jawed feeders. -While prey learns to look right, they leave their left flank exposed to the scale eater with a jaw that curves to right. |
| Jaw orientation heritable | -attack left flank or attack right flank -These 2 strategies are fixed & their success depends on their relative frequency in the pop. -alternate alleles could be responsible for 2 phenotypes. |
| Balancing selection | -Over-dominance: -selective advantage of heterozygotes maintains genetic variability (or multiple genes) within a pop. -Frequency Dependent selection: selective advantage of rare genotype maintains genetic variability. |
| Fixation | - Directional selection & genetic drift fix one allele at expense of others (P=1) - One allele eventually replaces others at a particular locus - Genetic variation lost over time |
| Peppered moths | -EX of natural selection -ex of evolution in action on a single gene Occurs in 2 forms: -Typical white/specked form -Melanic/black form -dark form caused by dominant mutation that occurs spontaneously. -Camo. for protection |
| Selection coefficient | measures intensity of natural selection in different habitats. |
| natural & artificial selection requirements: | -individuals in a pop. must vary in their phenotypes -phenotypes must be influenced by genotypes -requirement for heritability |
| quantitative genetics | -few ex. of selection acting on different alleles of a single gene. -Melanism in Biston betularia (peppered moths) -Heterozygous advantage in sickle cell anemia -competition for limited resources |
| 5.) Unequal survival | -Natural selection -differential survival of individuals (genotypes) in a finite pop. -selection usually acting on polygenic traits |
| Genetic drift | -group of small pop. will diverge in allele frequencies because of random sampling in each generations. -Genetic differentiation between pop. -results in genotypic change in a pop. without selection(neutral evolution). -suggests maintaining several small pop. can maintain genetic diversity in conservation programs. -Inbreeding like effect when pooled - Wahlund effect |
| Founder effect | loss of variability in small start-up pop. -probably limits occurrence of invasive species -sometimes advantageous -EX: Argentine ants & unicoloniality -bottleneck -disease or environmental catastrophe temporarily reduces pop. size. |
| 4.) Small pop. size | Dramatic shifts in allele frequencies over short # of generations. - Alleles can be lost (p or q=0) or fixed (p or q=1). EX: loss of genetic variability in cheetahs -vulnerable to disease, environmental fluctuations |
| 3.) Migration | -Immigration/emigration between pop. shifts allelic & genotypic composition of pop. -Outbreeding depression: crosses between individuals from different pop. have lower fitness progeny from crosses between individuals from the same pop. -Breakup of beneficial interaction between genes -Less fit intermediate for additive genetic trait -Can be masked by heterosis- beneficial parental gene combinations not broken up until F2 |
| 1.) Nonrandom mating | mating between individuals of the same phenotype or by those who live nearby -Inbreeding consanguineous mating: matings of the same blood. -Assortive Mating: the mating of phenotypically similar organisms. -both matings reduce # of heterozygotes and increases # of homozygotes. |
| 2.) Population Subdivision Geographical/ ecological barriers: | -interfere with completely random mating (panmixia) - allele freq. are not uniform throughout the pop. |
| FST | a measure of genetic distance between subpopulations |
| Wahlund effect | when 2 populations in HWE combine results in merged pop. with a deficit of heterozygotes. |
| inbreeding depression | -when individuals with similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to survive and reproduce. -deleterious recessive alleles come together in homozygotes with reduced fitness. EX: -Xeroderma Pigmentosum: high incident from marriages between 1st cousins. -Albinism: Hopi Indians, Kuna Important issue in conserving small, endangered populations. |
| Genes in pop. may not be in HWE due to: | 1. Non-random mating 2. Population subdivision 3. Migration 4. Small pop. size 5. Unequal survival |
| HWE for X-linked genes | frequency of X linked genotype corresponds with: -Homogametic sex (XX) : p2 + 2pq + q2 -Heterogametic sex (XY): p + q |
| Hardy-Weinberg equilibrium | -describes expected genotypic frequencies when gametes in a population form zygotes in all possible combinations. -allele & genotype frequencies don't change from generation to generation with some important assumptions. -Can also use HWE to predict allele frequencies from genotype frequencies. .can be used to calculate frequency of carriers of a recessive disease causing allele(cystic fibrosis). |
| HWE assumptions | -Random mating in a large population (panmitic pop)-no assortative mating. -no mutations that introduce new alleles (genotypes) -no migration: closed population-no migrants introducing additional or new genotypes. -No selection that changes genotype frequencies-all genotypes have an equal chance of survival. If ANY assumptions not met, population may not be in HWE. |
| population genetics focuses on | -organism with diploid genetics -1 gene with 2 alleles |
| twin studies and personality | -concluded that identicals reared apart were as much alike as identicals reared together in personality characteristics. -implies that environment (cultural influence) plays little role |
| Schizophrenia | -loss of ability to organize thoughts & perceptions - withdraw from reality -High concordance twins -M2 identical 45-60% -D2 Fraternal 10-20% |
| IQ | -M2T: identical, together 0.8 concordance -M2A: identical, apart 0.7 concordance -D2T: fraternal, together 0.2 concordance -D2A: fraternal, apart 0.3 concordance |
| Adopted individual studies | shared environment but no shared genes |
| concordance values | % of pairs in which both twins express the trait -if value is higher than M2 twins than D2 twins implies the trait has important genetic compound. |
| Dizygotic twins | -often called fraternal twins, occurring when two eggs each get fertilized by two different sperm, resulting in two zygotes in the uterus at the same time -relatedness = 0.5 |
| Monozygotic twins (M2) | identical twins -same fertilized egg -relatedness= 1 |
| Twin studies | -a common method of investigating whether nature or nurture affects behavior -also used to tease apart role of shared genes & the envir |
| artificial selection | Breeding organisms with specific traits in order to produce offspring with identical traits. |
| Narrow sense heritability | -additive alleles raise or lower the value of a trait in an addictive way. -proportion of total variance thats due to addictive genetic differences among individuals(addictive alleles) |
| Blue/ white colony selection | only bacteria that have a plasmid with antibiotic resistance grow. -White colonies have insert Blue colonies do not have insert. |
| broad sense heritability | Vg/Vp -proportion of total variance that's due to genetic differences among individuals (H2) H2=Vg/Vt |
| Hybrid Vigor | unusual growth, strength, & health of heterozygous hybrids derived from 2 less vigorous homozygous parents. |
| Polygenic Trait variation | variation in inbred lines due to the environment -variation in F1 also due to envi Individuals are heterozygous for the same 2 alleles at each gene. -Variation in F2 due to environment & independent assortment of alleles of different genes. |
| self-fertilization - loss of variability | -self fertilization (or crosses) of heterozygotes results in 50% loss of heterozygotes each generation. -Inbreeding reduces # of heterozygotes -Inbreeding increases homozygote # & probability that deleterious alleles come together. |
| Corolla length | -Corolla length in tobacco flowers is influenced by multiple genes & environment. |
| Grain color in wheat | -3 genes determine color -Genes are semi-dominant (same as incomplete dominant) -EX: red, pink, white snapdragon flower color -Degree of redness depends on # of pigment contributing alleles. |
| Cheating gene | Vasopressin receptor allele in men named 334 associated with difficulties in their marriage. -334 versions seem to result in a decrease in receptor # due to reduced gene expression. |
| Vasopressin | -antidiuretic hormone -peptide hormone produced by pituitary gland -Different vasopressin receptor alleles associated with monogamy & polygamy involves (affects # of receptors) -Monogamy: many receptors, long time bonding with mate, high levels of paternal behavior & intense aggression towards strangers for defense territory, nest & mate. -Polygamy: few receptors, multiple mates, lack of paternal & territorial behavior |
| Oxytocin | -"love gene" -encodes small peptide hormone (9 amino acids) -Released by pituitary gland -Mice with mutant oxytocin gene don't produce oxytocin (null allele). -Oxytocin also associated with bonding between mother & baby in humans. |