Chromosomes and linkage Flashcards
What are the benefits of using drosophila melanogaster as a test subject?
Easy to rear, rapid generation time
What were Morgans experiments on drosophila melanogaster?
Crossed eye colour and wings . expected four different equal outcomes. Discovered that the two characters didn’t independently assort, so much be linked
What is recombination?
Crossing over of chromosomes
Why does the proportion of recombinants formed vary?
Depends on which genes are looked at, may reflect the distance between the genes
What is a genetic map?
An ordered list of genetic loci along a particular chromosome
What affects the probability of a crossover between genes?
How far apart they are, higher probability if further away, have a higher recombination fraction
What is a linkage map?
A genetic map based on recombination frequencies
What does the map represent?
Distance between the genes
What are double recombinants?
two homologus chromosomes crossing over at two points
What occurs as a result of crossing over?
New, fitter genotypes, also can break up co-adaptive gene combinations
