Ch 5 Linkage, Recombination & Eukaryotic Gene Mapping

Question 1

linkage genes

Answer 1

genes located close together on the same chromosome; travel together in meiosis, eventually arriving at the same destination (the same gamete), and are not expected to assort independently

Question 2

linkage group

Answer 2

linked genes belong to this group

Question 3

nonrecombinant gametes

Answer 3

gametes that contain only original combinations of alleles present in the parents, or parental gametes

Question 4

nonrecombinant progeny

Answer 4

progeny display the original combinations of traits present in the P generation, or parental progeny

Question 5

recombinant gametes

Answer 5

gametes with new combinations of alleles

Question 6

recombinant progeny

Answer 6

progeny with new combinations of traits formed from recombinant gametes

Question 7

recombination frequency

Answer 7

percentage of recombinant progeny produced in a cross or rate of recombination
equal to the number of recombinant progeny divided by the total number of progeny multiplied by 100

Question 8

coupling (or cis configuration)

Answer 8

wild-type alleles are found on one chromosome and mutant alleles are found on the other chromosome

Question 9

repulsion (or trans configuration)

Answer 9

each chromosome contains one wild-type and one mutant allele

Question 10

chi-square test for independence

Answer 10

allows us to evaluate whether the segregation of alleles at one locus is independent of the segregation of alleles at another locus without making any assumption about the probability of single-locus genotypes

Question 11

genetic maps

Answer 11

chromosome maps calculated by using the genetic phenomenon of recombination

Question 12

physical maps

Answer 12

chromosome maps calculated by using physical distances along the chromosome (often expressed as numbers of base pairs(

Question 13

map units

Answer 13

distances on genetic maps; abbreviated as m.u.

equal to a 1% recombination rate; also called centiMorgans (cM)

Question 14

two-point testcross

Answer 14

testcross between two genes

Question 15

three-point testcross

Answer 15

more efficient mapping technique is a testcross for three genes
the order of the three genes can be established in a single set of progeny, and some double crossovers can usually be detected, providing more accurate map distances

Question 16

interference

Answer 16

the degree to which one crossover interferes with additional crossovers in the same region

Question 17

coefficient of coincidence

Answer 17

the ratio of observed double crossovers to expected double crossovers
calculated by number of observed double crossovers divided by the number of expected double crossovers