Lecture 3/4 Flashcards
What is complementation?
occurs when two organisms have different homozygous recessive mutations that produce the same phenotype, and then when they cross they produce an offspring that carries the wild-type phenotype
When the wild-type offspring of complementation are crossed, what is the phenotypic ratio of wildtype to recessive?
9:7
What is the one condition of complementation?
the mutations must be on different genes
What is genetic epistasis?
when one, epistatic, gene masks the expression of a hypostatic gene at a different location
What is recessive epistasis and what phenotypic ratio does it produce?
when homozygous recessives at one gene pair masks the expression of other genes, 9:3:4
What is dominant epistasis and what phenotypic ratio does it produce?
when one dominant allele at one gene masks the expression of the other gene, 12:3:1
What is pleiotropy?
when a single gene is responsible for a number of distinct and seemingly unrelated phenotypic effects
What is inbreeding depression?
when the population is full of homozygous recessive mutations so generations become less vigorous as they go on
What is heterosis?
When two separate inbred lines are crossed and the offspring is heterozygous and vigor
What assumptions must be met for the Hardy-weinberg principle?
the population must be large, randomly mating, unaffected by mutation, migration or natural selection
What are the hardy-weinberg equations?
p^2 + 2pq + q^2 = 1
p + q = 1
What is dosage compensation?
the equalization of the gene expression in X chromosomes to Y chromosomes ex: X inactivation
What does an XO and XXY genotype represent?
XO - turners syndrome
XXY - Kleinfeld’s syndrome
In the hardy Weinberg principle, what are allelic frequency and what are genotype frequencies?
allele frequency: p,q
genotype frequency: p^2, 2pq, q^2
