Ch. 7 Linkage and Recombination Flashcards
What is the sorting of alleles into new combinations?
recombination
What are genes that are close together on the same chromosome?
linked
If crossing over occurs between two genes 100% of the time, what is recombination frequency?
50%
The allele combination in the offspring is the same combination as in the parent
nonrecombinant
The allele combination in the offspring is different than the combinations in the parent
recombinant
In a heterozygote testcross, the offspring of the type of gene results in 4 phenotypes in equal proportions
unlinked
In a heterozygote testcross, the offspring of this type of gene results in 4 phenotypes where the nonrecom. > recomb
incompletely linked
In a heterozygote testcross, the offspring of this type of gene results in 2 phenotypes in the offspring (both nonrecom.)
completely linked
In a heterozygote, the dominant alleles are the same chromosome
coupling
cis
What is the maximum recombination frequency?
50%
In a heterozygote, the dominant alleles are in the opposite chromosomes
repulsion
trans
If the phenotype of the nonrecombinant offspring matches the phenotype of the parents, the alleles are in
coupling
If the phenotype of the non recombinant offspring does not match the phenotype of the parents, the alleles are in
repulsion
True or False: in incompletely linked genes, there will always be more non recombinants then recombinants
True
Which of the following would result in the lowest offspring numbers?
2 crossovers
What is the first step in a three-point test cross?
determine gene order
How do you determine the middle gene?
compare the non recombinants to double crossovers
How do you calculate recombination frequencies?
number of recombinants/total
How many numbers do you add together when doing recombination frequency in three-point test cross?
4
How do you calculate the expected probability of double crossovers?
multiply the two recombination frequencies
How do you find the expected number of offspring with a double crossover?
total offspring x probability
How do you calculate coefficient of coincidence?
observed double crossovers/expected double crossovers
How do you calculate interference?
1 - coefficient of coincidence
My interference is 0.23. What does this mean
I am observing 77% of double crossovers
I am not observing 23% of double crossovers
