chromosome mapping Flashcards
map units
- the distance between genes on the same chromosome
- (number of recombinants/number of total offspring) x 100
- can be translated to a % recombination
- the larger the map units, the more likely recombination of the genes will take place
Possible crossover scenarios for a dihybrid cross
1) genes A and B are independently assorting - 4 classes of offspring with a 9:3:3:1 ratio
2) genes A and B are tightly linked so that crossing over does not happen - 2 classes of offspring with a 3:1 ratio
3) genes A and B are linked and crossing-over occurs with variation in 3:1 ratio (ex 24:1:1:7)
what is the cap % of recombination and why
50% (50 map units)
- if more than 50 % then you are independently assorted
cis and trans alleles in a dihybrid cross
cis = AB || ab
trans = Ab || aB
tracking linked genes ex: ABO blood type and nail-patella syndrome
often nail patella syndrome is inherited with BO blood, however due to recombination some individuals who have OO blood might appear affected and some with BO may not appear affected