Chapter 7 Flashcards
nonrecombinant gametes/parental gametes
gametes that contain only original combinations of alleles that were present in the parents
nonrecombinant progeny
display original combinations of traits present in the P generation
if genes are completely linked
no crossing over
if genes are unlinked
assort independently
recombinant gametes
gametes with new combinations of alleles
what happens in independent assortment (what does it produce)
nonrecombinant and recombinant gametes are produced in equal proportions
- 1:1:1:1 ratio - two types of recombinant progeny and two types of nonrecombinant progeny in equal proportions
what happens when no crossing over takes place?
each gamete receives a nonrecombinant chromosome with an original combination of alleles
what happens when recombination takes place
1/2 of the resulting gametes will have an unchanged chromosome (nonrecombinant) and the other 1/2 will have a recombinant chromosome
recombination frequency
number of recombinant progeny/total number of progeny x 100%
coupling
arrangement in which wild-type alleles are found on one chromosome and mutant alleles are found on other
repulsion
arrangement within each chromosome contains one wild-type and one mutant allele
incomplete linkage
intermediate and genes are physically linked on the same chromosome; however, occasional crossovers break up linkage and allow the genes to recombine
- nonrecombinants are produced more frequently than the recombinants
chi square test of independence with a probability of less than 0.05
means that the observed values are significantly different from the expected values and genes are not independently ASSORTED
WHAT DOES A DOUBLE CROSSOVER BETWEEN TWO LINKED genes produce
- restores original parental combination of alleles
- produce only recombinant genes
Gene distance formula
SCOa +SCOb + (all DCO) / total
