6.2 Phenotypic Ratios, linkage & epistasis Flashcards
(Linkage) ratios observed in a dihybrid cross can differ significantly from expected why?
Linkage
(Linkage) what is linkage?
Genes on the same chromosome
(Linkage) linked genes are inherited as a single what? And what is there none of?
Unit
No independent assortment unless separated by chiasmata
(Linkage) what is sex linkage?
Linked genes are on sex chromosomes
(Linkage) what is autosomal linkage?
Linked genes are on normal chromosomes
(Linkage) what does crossing over in meiosis result in?
Separation of linked genes
(Linkage) the closer the linked genes on the chromosome the less chance of what?
Separation
(Recombinant offspring) what do recombinant offspring have?
Different combination of alleles to parents
(Recombinant offspring) recombination frequency is a measure of what?
How much crossing over occurs in meiosis
(Recombinant offspring) a frequency of 50% indicates what?
No linkage and genes are on different chromosomes
(Recombinant offspring) a frequency of less than 50% indicates what?
There is gene linkage and independent assortment has been hindered
(Recombinant offspring) how do you calculate recombination frequency?
(No. Of recombinant offspring ÷ total number of offspring) x 100
Why will observed results from a genetic cross almost always differ from expected?
Due to chance
