X-Linked Traits and Recombination Flashcards
Do sex linked traits vary between male and female?
Yes
Red-green colour blindness is a sex-lined trait
Yes
What will the offspring be if: Colour blindness allele is recessive.
Mum has normal vision, dad is colour blind?
That means that all daughters are carriers and all sons are normal.
What will offspring be if: mum is a carrier female and mates with a normal male?
Half of the daughters are normal, half the daughters are carriers, half the sons are normal, half the sons are colour blind
How are linked genes inherited?
If a pair of genes is on the same chromosome we call them linked. Linked genes show biases to parental genotypes.
How can we determine the order and location of genes within a chromosome?
By using recombination frequencies
What does it mean if the phenotypic ratio is not what we would expect (not equal numbers of parental types and recombinant types)?
The two genes do not assort independently, therefore they are on the same chromosome
Why do we get some recombinants even when we have linked genes?
Crossing over
What is the term for the proportion of recombinant gametes?
The recombination frequency
How do we determine the recombination frequency?
Add up the total of new combinations and divide that by the total number of combinations
What will a smaller distance between two linked genes mean?
They are less likely to be separated (lower recombination frequency) (because a recombinant event is less likely to get between them and separate them, if that area gets hit its likely they will both go together)
Is there a linear relationship between recombination frequency and the distance the linked genes are from each other on the chromosome?
Yes
What is the relative recombination frequency of genes that are distant (unlinked)?
About 50%
