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46 Cards in this Set
- Front
- Back
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F2 dominant to recessive ratio
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- 3:1 (Mendelian ratio)
- half of F2 generation will EXPRESS dominant trait with recessive trait latent |
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phenotype
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- expression of a trait through action of enzymes & structural proteins
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complete dominance
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- for any one trait, a diploid individual will have 2 homologous chromosomes coding for that trait
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homologous chromosomes
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genes located at same locus; each gene contributes an allele
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homozyogous for a trait
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tow dominant or two recessive alleles
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heterozygous for a trait
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one dominant & one recessive allele (hybrid)
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Law of Segregation
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- Mendel's First Law of Heredity
- alleles segregate independtly of each other when forming gametes - phenotypic expression is not a blend of the two (dominance) |
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partial/incomplete dominance
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phenotype intermediate b/t homozgous counterparts; same capital letter w/ prime or superscript (CC' or CrCw)
- alleles are codominant - e.g. human blood type alleles (heterozygote exhibits A and B antigens on blood cell membranes) |
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Law of Independent Assortment
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- Mendel's Second Law of Heredity
- genes located on different chromosomes assort independently of each other - genes that code for different traits, when located on different chromosomes, don't affect e/o during gamete formation - chance that 2 genes on same chromosome will remain together during gamete formation is indirectly proportional to the distance separating them |
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dihybrid cross
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- cross b/t F1 offspring of 2 individuals that differ in 2traits of particular interest
- e.g. For example, Bb × Bb [B = brown. b = blue. BB = Dark brown. Bb = Brown (not blue). bb = Blue.] - often used to test for dominant & recessive genes in 2 separate characteristics |
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phenotypic ratio of a dihybrid cross
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9:3:3:1
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sex chromosomes
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- 23rd pair of chromosomes establishes sex
- XY if male (all other chromosomes XX) - gene on a sex chromsome is sex-linked (allele usually carried by X, so is expressed in male whether dominant or recessive) |
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karyotype
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map of chromosomes
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Barr body
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in females, one of the X sex chromosomes condenses & most of its genes become inactive
- formed at random so active allele slit about evenly among cells |
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carrier of a trait
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carries a recessive trait without expressing it
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hemophilia
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- sex-linked disease
- cross b/t female carrier & healthy male gives male offspring a 50% chance of having the disease |
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gene pool
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total of all alleles in a population
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evolution
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a change in the gene pool (even if ratio of phenotypes changes, the population won't have evolved unless ratio of alleles changes)
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taxonomy classifications
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Kingdom
Phylus (*divisions for plants & fungi) Class Order Family Genus Species |
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Vertebrata
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subphylum in the phylum Chordata (Mammalia is a class)
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How does ontogeny reapitulate phylogeny?
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course of development of an organism from embryo to adult reflects its evolutionary history
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domains
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- superkingdoms
- Bacteria, Archaea & Eukarya - Eukarya contains kingdoms of Protista, Fungi, Plantae & Animalia - kingdom Monera obsolete (Bacteria/Archaea) - Archaea more closely related to Eukarya than Bacteria |
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organism name
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Genus species
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species
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organisms that can reproduce fertile offspring with each other (though this does not NECESSARILY mean they are the same species); all organisms which normally reproduce selectively fit offspring in the wild
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What factors could prevent organisms of different species from producing fit offspring?
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- geographic isolation
- habitat isolation (same location, different habitats) - seasonal isolation (mate in different seasons) - mechanical isolation (physically impossible to mate) - gametic isolation (gametes incompatible) - development isolation (fertilized embryo deveops improperly) - hybrid inviability/sterility (hybrid malformed) - selective hybrid elimination (hybrid is less fit) - behavioral isolation (different mating rituals) |
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niche
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the way in which a species exploits its environment; no 2 species can occupy same niche indefinitely (survival of the fittest)
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r- selection
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- reproductive strategy of producing large # of offspring that mature rapidly with little/no parental care
- high brood mortality rate - exponential population growth curves - usually in unpredicatable, changing environments affected by density independent factors (floods, drastic temp changes) - most species mix b/t K- & r-selection |
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K-selection
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- reproductive strategy with small brood size, slow maturing offspring & strong parental care)
- sigmoidal growth curve that levels off at carrying capacity (maximum # organisms an environment can maintain - a density-dependent factor) - most species mix b/t K- & r-selection |
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speciation
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process by which new species are formed when gene flow ceases /t two sectkions of a population; can be spurred by geographic, seasonal & behavioral isolation
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adaptive radiation
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when several separate species aris from a single ancestral species (e.g. Galapagos finches)
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evolutionary bottleneck
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species faces severe crisis that causes shift in allelic frequencies of crisis survivors
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divergent evolution
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two or more species evolving from same group maintain similar structure from common ancestor (homologous structrue)
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convergent evolution
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two species independently evolve similar structures (analogous/homoplastic structures - e.g. bats and birds both have wings, but do not share a common ancestor)
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polymorphism
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occurrence of distinct phenotypic forms (height, flower color, etc.)
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symbiosis
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- "mutualism" if beneficial
- "commensalism" if benefitical for one and does not affect the other - "parasitism" if benefitical for one and detrimental to other - "enslavement" if one species enslaves another |
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What 5 characteristics does a population need to be in Hardy-Weinberg equilibrium?
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1. large population
2. mutational equilibrium 3. immigration/emigration must not change gene pool 4. random mating 5. no selection for the fittest organism *may explain how less frequent alleles are maintained in the population; no real population ever completely has all these |
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genetic drift
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in small populations, one allele may be permanently lost due to death of all members having that allele; not caused by selective pressure - occurs randomly
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mutational equilibrium
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rate of forward mutations equals rate of backwards mutations
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p + q = 1
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binomial therom (p^2 + 2pq + q^2) predicts GT frequency of a gene w/ only 2 alleles in a population in Hardy-Weinberg equilibrium (e.g. so if 80% of alleles in population are A, then 80% of gametes will be A, and the probability that 2 A's come together is 0.8^2 = 64%)
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Urey-Miller experiment
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attempted to recreate atmosphere of early earth & resulted in autosynthesis of urea, amino acids, adenine, etc. (reducing environment created by clouds of dihydrogen sulfide, ammonia & methane)
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coavervates
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lipid or protein bilayer bubbles (first cells thought to have evolved); form spontaneously & grow from fat molecules suspended in water
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photosynthetic bacteria
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oxygen producing ancestors of cyanobacteria that could use sunlight & water to reduce CO2
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Were earliest organisms likely heterotrophs or autotrophs?
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heterotrophs
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chordata
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phylum containing humans; have bilateral symmetry
- deterostomes (anus develops from/near blastopore) - have coelom (body cavity w/in mesodermal tissue) - notochord (embryonic axial support), pharyngeal slits, dorsal/hollow nerve cord & tail at some stage of development |
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Vertebrata
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subphylum of Chordata with notochord replaced by segmented cartilage or bone structure & distinct brain enclosed in a skull; composed of 2 classes of jawless fish, carilaginous fish, bony fish, amphibians, reptiles, birds & mammals
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What arose from what?
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- amphibians arose from boney fish
- reptiles arose from amphibians - birds & mammals arose from reptiles |
