Exam 1: Lecture 13

Question 1

male pattern baldness is a _ trait

Answer 1

hereditary; x-linked gene

Question 2

principle of independent assortment

Answer 2

alleles at one locus sort independently from alleles at another locus (w/o influence from other genes)

Question 3

recombination

Answer 3

alleles sort into new combinations

Question 4

complete linkage leads to

Answer 4

nonrecombinant gametes and nonrecombinant progeny

Question 5

what restores independent assortment

Answer 5

recombination can restore distance to segregate independently (prophase 1 in meiosis)

Question 6

single crossover

Answer 6

half nonrecombinant gametes, half recombinant gametes

Question 7

conclusion if genes are completely linked (no crossing over)

Answer 7

only nonrecombinant progeny are produced

Question 8

conclusion if genes are unlinked (assort independently)

Answer 8

half the progeny are are recombinant and half the progeny are not

Question 9

how to calculate recombination frequency (testing for independent assortment)

Answer 9

recombination frequency = (# recombinant progeny/total # progeny) x 100%

Question 10

cis configuration

Answer 10

one chromosome contains both wild-type alleles, one chromosome contains both mutant alleles

Question 11

trans configuration

Answer 11

wild-type allele AND mutant allele are found on the sames chromosome

Question 12

a high chi square # in analysis for independence suggests

Answer 12

they must be linked; traits do not segregate independently

Question 13

gene mapping with recombination frequencies: genetic maps

Answer 13

are determined by recombinant frequency how much recombination happens btwn 2 genes on a chromosome
(cM=crossover frequency of 0.01 in a single generation)

Question 14

gene mapping with recombination frequencies: physical maps

Answer 14

are determined by the nucleotide position (# of nucleotides on chromosome)

Question 15

a two-strand double crossover btwn two linked genes produces

Answer 15

only nonrecombinant gametes (second crossover will reverse the effects of the first, restoring original parental combination of alleles)

Question 16

recombination happens more frequently on _ arms

Answer 16

the long arms

Question 17

the _ the more likely a crossover event

Answer 17

further apart

Question 18

(sum of all single and double crossovers)/(total progeny) =

Answer 18

recombination frequencies

Question 19

what is interference and how do you calculate it?

Answer 19

A measure of the independence of crossovers from each other, calculated by subtracting the coefficient of coincidence from 1.

Question 20

what is the coefficient of coincidence

Answer 20

the ratio of observed to expected double recombinants

observed double crossovers)/(expected double crossovers

Question 21

B and C is 50%, double crossovers between A and C should be

Answer 21

50%*50% = 25%

Question 22

usu the # of double crossovers observed is less than expected bc the 1st crossover somehow inhibits the occurrence of a second crossover describes:

Answer 22

interference