Linkage and Epistasis Flashcards
Where is sex linkage carried out?
On sex chromosomes
Female = XX
Male = XY
Why is it more likely for males than females to show recessive phenotypes?
Y chromosome is smaller than the X chromosome so carries fewer genes. Males only have 1 X chromosome and will express the characteristic even if it is recessive (so they only need 1 recessive allele whereas females would need 2)
Where is autosomal linkage carried out?
On autosomes (body cells)
Why are genes on the same autosome said to be linked?
They will stay together during independent segregation meaning that alleles will be passed onto offspring. The closer together the 2 genes are on the autosome the more closely linked they are the the less likely crossing over will split them up.
What is epistasis?
When 1 gene influences (affects or masks) the expression of another gene. An interaction between 2 non linked genes causes 1 gened to mask the expression of the other. (always dihybrid)
What is an epistatic gene?
A gene that suppresses another gene
What is a hypostatic gene?
A gene which is being suppressed
