Genetics & Evolution Flashcards
The genetic combination possessed by an individual is known as ______, and the manifestation of it as an observable trait is known _______?
Genotype & Phenotype
The specific location on a chromosome is known as ?
Locus
When only one dominant & recessive allele exists for a gene, there is said to be what ?
Complete dominance
When more than 1 dominant allele exists for gene, this is known as ?
Codominance
When a heterozygote expresses a phenotype that is an intermediate between the 2 homozygous genotypes, this is known as ?
Incomplete dominance
A population measure defined by the proportion of individuals in the population that phenotypically express the allele is known as ?
Penetrance
*more than 40 sequence repeats = full penetrance
Varying phenotypes despite identical genotypes is known as ?
Expressivity
What are the 4 basic tenets of Mendel’s 1st law of segregation ?
- Genes exist in alternative forms
- An organism has 2 alleles
- 2 alleles segregate during meiosis
- If 2 alleles are different, 1 will be expressed & 1 will be silenced
What does Mendel’s 2nd law of independent assortment state ?
The the inheritance of one allele does not affect the inheritance of another
*unlinked genes
All of the alleles that exist within a species are known as the what ?
Gene pool
Elements known as transposons can function to do what ?
Insert & remove themselves from the genome freely
What are the different types of chromosomal mutations ?
Deletion: large segment of DNA is lost from chromosome
Duplication: when a segment of DNA is copied multiple times in the genome
Inversion: when a segment of DNA is reversed within the chromosome
Insertion: when a segment of DNA is moved from 1 chromosome to another
Translocation: when a segment of DNA is swapped w/ another DNA segment
Defects in genes required for metabolism are known as ?
Inborn errors of metabolism
A flow of genes between species is known as ?
Genetic leakage
*Can lead to hybrid offspring
Genetic drift refers to changes in the composition of the gene pool due to chance. What are possible effects of genetic drift?
Founder effect: reproductive isolation (can be due to bottleneck: drastic decrease in population that leads to small size of available breeding)
Inbreeding
A ____ is used to determine an unknown genotype
Test cross
What should be kept in mind in regards to sex-linked traits ?
- X linked
- Males more susceptible
- Typically recessive
Finish the statement: the further apart 2 genes are, the more likely….?
There will be a point of crossing over (chiasma)
What are the foundations of Hardy-Weinberg equilibrium ?
- Large population (no genetic drift)
- No mutations that affect gene pool
- No sexual selection (random mating)
- No immigration or emigration
- Equal succession of genes being reproduced
How does punctuated equilibrium contrast w/ Darwin’s theory ?
PE suggests that changes in some species occur in rapid burst rather than evenly over time as suggested by natural selection
What are the different modes of natural selection ?
Stabilizing: keeps phenotypes within a specific range by selecting against extremes
Directional: dominance of an initially extreme phenotype due to adaptive pressures
Disruptive: 2 extreme phenotypes are selected over the norm (facilitated by polymorphisms: naturally occurring differences between members of the same population)
The rapid rise of a # of different species from a common ancestor is known as ?
Adaptive radiation
*Benefit = niches
Formation of new species through evolution is termed ?
Speciation
What are the 2 different forms of reproductive isolation, & how do they contrast ?
Prezygotic mechanisms prevent formation of zygote completely, while postzygotic mechanisms allow for gamete fusion but yield nonviable or sterile offspring
What are the 3 different patterns of evolution ?
Divergent: independent development of dissimilar characteristics in 2 or more lineages sharing a common ancestor (Ex: cats & seals)
Parallel: related species evolve in similar ways for long periods in response to analogous environmental selection pressures
Convergent: independent development of similar characteristics in 2 or more lineages NOT sharing a common recent ancestor (Ex: fish & dolphin)
Recombinant frequency values close to ___ show linked genes, while values close to ___ indicate independent assortment.
0% & 50%
