Deck 7: Genetic Linkage and Mapping in Eukaryotes

Question 1

Experimental evidence that crossing over occurs between the X chromosomes of female Drosophila was provided by ________.

A) Morgan
B) Punnett
C) Darwin
D) Bateson

Answer 1

A

Question 2

Which of the following is not one of the properties of gene linkage that Morgan obtained from his experiments?

A) Genes that are on the same chromosome may be inherited together.
B) Crossing over exchanges pieces of chromosomes and creates new allele combinations.
C) The likelihood of crossing over occurring between two genes is dependent on the distance of the genes from one another.
D) Genes that are on the same chromosome are always transmitted together as a unit.

Answer 2

D

Question 3

The process of recombination may rarely occur during mitosis.

Answer 3

True

Question 4

Which of the following statistical tests is used to determine if two genes are linked or assorting independently?

A) sum rule
B) binomial expansion
C) product rule
D) chi square test

Question 5

In a chi square test to determine if two genes are linked or assorting independently,what is the default (null)hypothesis that is tested?

A) The genes are linked to one another.
B) The genes are assorting independently.
C) The genes are located on the sex chromosomes.
D) No crossing over occurs.

Question 6

The individual who is credited with discovering genetic linkage in Drosophila is ________.

A) Thomas Hunt Morgan
B) Gregor Mendel
C) Alfred Sturtevant
D) Barbara McClintock

Question 7

Twin spotting provides evidence of what genetic event?

A) meiotic recombination
B) mitotic recombination
C) linkage
D) mutation

Question 8

The visual proof that chromosomes exchange pieces of information during crossing over was provided by ________.

A) Bateson and Punnett
B) Morgan and Bridges
C) Creighton and McClintock
D) Watson and Crick

Question 9

While mapping two genes in Drosophila,you observe 30 recombinants among 200 total offspring.What is the distance between these genes?

A) 30 map units
B) 6.67 map units
C) 200 map units
D) 15 map units

Question 10

A map distance of 23.6 between two genes indicates which of the following?

A) The genes are 23.6 millimeters apart.
B) There are 23.6 other genes between the two genes of interest.
C) 23.6% of the offspring exhibit recombination between the two genes.
D) 23.6% of the offspring do not survive.

Question 11

An organism that contains patches of tissue that vary for a specific characteristic,such as a pigment,is an example of ________.

A) linkage
B) meiotic recombination
C) mitotic recombination
D) translocations

Question 12

In a mapping experiment with three genes,which phenotype should occur most often in the F₂ offspring?

A) parental phenotypes
B) phenotypes of individuals with single crossover events
C) phenotypes of individuals with double crossover events
D) All of these choices should be equal in the F₂ generation.

Question 13

Assume that genes C and D are located on the same chromosome.On one chromosome alleles C and D are found,while the homologue contains alleles c and d.Which of the following would be an example of a recombination event?

A) alleles C and D together on one chromosome
B) alleles c and d together on one chromosome
C) alleles C and d together on one chromosome
D) alleles c and D together on one chromosome
E) both alleles C and d together on one chromosome and alleles c and D together on one chromosome

Question 14

The first observational evidence that genes may be inherited together rather than by simple Mendelian inheritance was provided by ________.

A) Mendel
B) Morgan and Bridges
C) Bateson and Punnett
D) Boveri and Sutton

Question 15

A genetic linkage map indicates the precise distance between two genes of interest.

Question 16

Crossing over is more likely to occur between genes that are ________ on a chromosome.

A) close together
B) far apart
C) not

Question 17

A testcross is always performed between the individual that is heterozygous for the genes to be mapped and an individual who is ________.

A) heterozygous for the genes
B) homozygous dominant for the genes
C) homozygous recessive for the genes
D) lacking the genes

Question 18

Which of the following are necessary characteristics of an organism in order to easily construct a genetic linkage map?

A) short generation times
B) produces large numbers of offspring
C) easily crossed
D) All of these choices are correct.

Question 19

Which of the following defines gene linkage?

A) Two or more genes that are physically connected on a chromosome.
B) Genes that are transmitted to the next generation as a group.
C) The process by which genetic information is exchanged between homologous chromosomes.
D) All of these choices are correct.
E) Both two or more genes that are physically connected on a chromosome and genes that are transmitted to the next generation as a group.

Question 20

The middle gene of a three gene mapping experiment can be determined by examining the genotypes of which of the following?

A) offspring that resemble the parents
B) offspring that exhibit a single crossover event
C) offspring that exhibit double crossover events
D) None of these choices are correct.

Question 21

The rearrangement of alleles by the process of crossing over is called genetic linkage.

Question 22

The parental genotypes for a series of crosses are wild-type male fruit flies mated to females with white eyes and miniature wings.The phenotypes of the F1 generation were wild-type females,and males with white eyes,and miniature wings,indicating sex chromosome linkage.These flies were allowed to mate with each other and produced the following offspring:
Red eyes,long wings 770
White eyes,miniature wings 716
Red eyes,miniature wings 401
White eyes,long wings 318
Total 2205
How many map units is the gene for eye color from the gene for wing length to the nearest tenth?

Question 23

Map distance is the number of recombinant offspring divided by the total number of nonrecombinant offspring.

Question 24

The parental genotypes for a series of crosses are wild-type male fruit flies mated to females with white eyes and miniature wings.The phenotypes of the F1 generation were wild-type females,and males with white eyes,and miniature wings,indicating sex chromosome linkage.These flies were allowed to mate with each other and produced the following offspring:
Red eyes,long wings 770
White eyes,miniature wings 716
Red eyes,miniature wings 401
White eyes,long wings 318
Total 2205
What is the chi square value for this data to the nearest hundredth?

Question 25

Creighton and McClintock worked with ________ as their model system to show that homologous chromosomes physically exchange genetic information during crossing over.

A) fruit flies
B) peas
C) corn
D) tobacco

Question 26

Map distances above 50 are considered unreliable due to the occurrence of double-crossovers between the genes.

Question 27

Another name for a chromosome is a ________,since it contains genes that are often inherited together.

A) linkage group
B) crossing over group
C) genetic recombinant
D) bivalent

Question 28

The locus is the physical place of a gene on a chromosome.

Question 29

Two genes that are located on the same chromosome are said to be ________.

A) linked
B) recombinant
C) parental-like
D) nonparental-like

Question 30

A map unit or centiMorgan is equal to a 10% recombination frequency.

Question 31

In humans,there are ________ autosomal linkage groups,plus an X and Y chromosome linkage group.

A) 23
B) 46
C) 22
D) 92

Question 32

Following crossing over,chromosomes with genetic combinations that resemble the parents are called nonrecombinant.