Epistasis Flashcards
1
Q
What is epistasis?
A
- the interaction of genes at different loci
2
Q
What is gene regulation?
A
- a form of epistasis
- with regulatory genes controlling the activity of structural genes
- e.g. the lac operon
3
Q
Where does gene interaction also occur?
A
4
Q
What does continuous variation involve?
A
multiple genes and epistasis occurs frequently
5
Q
How does a pathway occur in epistasis?
A
- parts of the pathway need to be expressed
- if one of these genes is not expressed then one step will be missing
- changes the phenotype
- intermedate molecule necessary the next reaction in the sequence is not produced
- therefore the substrate for the enxt enzyme in the pathway will not be produced, so the expression of this gene will not be observed in the phenotype
6
Q
What is a hypostatic gene?
A
- a gene that is affected by another gene
7
Q
What is a epistatic gene?
A
a gene that affects the expression of another gene
8
Q
What may determine the influence of an epistatic gene?
A
- an epistatic gene may influence the activity of other genes as a result of the presence of dominant or recessive alleles
9
Q
When does dominant epistasis occur?
A
- dominant epistasis happens when the dominant allele of one gene masks the expression of all alleles of another gene
- they will have the trait
10
Q
what is the ratio for dominant epistasis?
A
12:3;1
11
Q
When does recessive epistasis occur?
A
- the recessive allele, or variation of a gene controls another gene
- recessive allele that displays epistasis weill control the expression of all alleles of the second gene
