Deck 6: Genetic Linkage and Mapping in Eukaryotes

Question 1

The process of recombination may rarely occur during mitosis.

Answer 1

True

Question 2

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
E) None of the answers are correct

Answer 2

C

Question 3

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

Answer 3

D

Question 4

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

Question 5

Which of the following defines the principle of 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 the answers 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 6

In a given mapping experiment, you expect that incidence of double crossovers is 3.5%, but you only observe 2.5%. This can be explained by .

A) Interference
B) Linkage
C) Coincidence
D) Segregation

Question 7

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
E) The distance between the genes is very small

Question 8

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 9

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 10

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 the answers are correct

Question 11

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
E) None of the answers are correct

Question 12

Twin spotting provides evidence of what genetic event?

A) Meiotic recombination
B) Mitotic recombination
C) Linkage
D) Mutation
E) Biological evolution

Question 13

The individual who is credited with producing the first genetic linkage map is .

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

Question 14

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 the answers are correct

Question 15

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 the answers should be equal in the F2 generation

Question 16

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

A) Close together
B) Far apart

Question 17

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 18

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

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

Question 19

An organism that contains patches of tissue that vary for a specific characteristic, such as a pigment is an example of which of the following?

A) Linkage
B) Meiotic recombination
C) Mitotic recombination
D) Translocations
E) None of the answers are correct

Question 20

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 21

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

Question 22

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

Question 23

In fungi, the diploid structures are called spores.

Question 24

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

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

Question 25

A negative interference value indicates that the first crossover event enhanced the occurrence of
additional crossover events in the region.

Question 26

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

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

Question 27

Which of the following procedures may be used to map genes in a fungi with an unordered tetrad ascus?

A) Testcross
B) Monohybrid cross
C) Dihybrid cross
D) Chi-square analysis
E) Analysis of interference

Question 28

The end result of meiosis in fungi is a tetrad of spores.

Question 29

Which of the following is not one of the principles of 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.

Question 30

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

Question 31

Creighton and McClintock worked with and 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 32

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

Question 33

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

Question 34

In fungi, the structure in which the position of the four spores in the ascus is an indication of their relationship to each other as they were produced during meiosis is called an .

A) Unordered tetrad
B) Unordered octad
C) Ordered tetrad
D) Ordered octad

Question 35

In haploid fungi, which of the following is used to calculate the distance between the centromere and the gene of interest?

A) Percent individuals experiencing double-crossover events
B) Number of diploid spores
C) Spores that have undergone first division segregation
D) Spores that have undergone second division segregation
E) None of the answers are correct

Question 36

A first division segregation (FDS) in the ordered octad ascus that has not had a crossover event has which of the following arrangements of the spores?

A) 3:1
B) 4:4
C) 2:4:2
D) 9:3:3:1

Question 37

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 38

You have calculated the interference value for a given mapping experiment to be 30%. What does this mean?

A) 30% more double crossovers occurred than expected
B) 30% fewer double crossovers occurred than expected
C) 70% more double crossovers occurred than expected
D) 70% fewer double crossovers occurred than expected

Question 39

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

Question 40

Algae and fungi spend the majority of their life cycle in the condition.

A) Diploid
B) Haploid
C) Triploid
D) Tetraploid

Question 41

A 2:2:2:2 pattern in an ordered octad ascus is an indication of first-division segregation.

Question 42

An ascus that contains two parental spores and two nonparental spores is called a tetratype.

Question 43

In fungal gene mapping, the abbreviation NPD stands for new parental ditype.

Question 44

The reproductive fungal structure that contains all of the products of a single meiotic division is called
the ascus.