Deck 7: Linkage,Crossing Over,And Chromosome Mapping In …

Question 1

Recombination is commonly the result of a process known as__________ which occurs in Prophase I of Meiosis.

A) Crossing over
B) Linkage
C) Disjunction
D) Non-disjunction
E) Formation of the mitotic spindles

Answer 1

A

Question 2

During the crossing over process:

A) Genetic information is physically exchanged
B) Tetrads are formed
C) Only two chromatids cross over at any one point
D) All of these are true statements
E) None of these are true statements

Answer 2

D

Question 3

The genetic map distance between two loci is roughly equal to

A) The estimated number of crossovers that occur between two points
B) The recombination frequency written as a percentage
C) The non-recombination frequency written as a percentage
D) The number of parental phenoytpes seen in the progeny
E) None of these

Answer 3

B

Question 4

Why doesn't an exchange between sister chromatids result in the production of a recombinant?

A) Sister chromatids are genetically identical and therefore an exchange would not show any change in phenotype
B) Sister chromatids are not genetically identical and therefore cannot exchange information
C) Sister chromatids are genetically identical and therefore cannot exchange information
D) Sister chromatids are not genetically identical and therefore an exchange would not show any change in phenotype
E) None of these explains this

Question 5

Typically,each crossover event produces how many recombinants?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 6

The phenomenon in which genes on the same chromosome are separated from each other during meiosis and new combinations of genes are formed is known as:

A) Linkage
B) Synapsis
C) Recombination
D) Nondisjunction
E) Disjunction

Question 7

Which of the following is a true statement about the linkage phase diagram R l / r L 1.The slash (/)separates alleles inherited from different parents
2)The alleles on the left and right of the slash indicate genotype on different homologous chromosomes
3)The genotype has the repulsion linkage phase

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these

Question 8

Which of the following statement is false regarding linked genes?

A) The more closely the genes are linked the less often they recombine
B) The recombination frequency for any set of genes often exceeds 50%
C) Recombination occurs most frequently between genes that are not closely linked
D) All of these are true statements regarding linked genes
E) All of these are false statements regarding linked genes

Question 9

Which of the following can be used to estimate the number of crossovers that occur during meiosis?

A) Count chiasmata
B) Count recombinant chromosomes
C) Count centromeres
D) Count chiasmata and Count recombinant chromosomes
E) Count recombinant chromosomes and Count centromeres

Question 10

Which of the following is a false statement regarding chiasmata and the time for crossing over?

A) The chiasmata are most visible and can be counted during late prophase 1 of meiosis
B) The chiasmata are the points where the physical exchange of genetic information occurs
C) Crossing over occurs in early to mid prophase 1 before chiasmata can be viewed
D) Crossing over occurs in late prophase at the time chiasmata can be viewed
E) The number of chiasmata is roughly proportional to the chromosome length

Question 11

Wild-type Drosophila females were mated to males homozygous for two autosomal mutations-vestigial (vg),which produces short wings,and black (b),which produces a black body.All the F? flies had long wings and gray bodies; thus,the wild-type alleles (vg? and b?)are dominant.The F? females were then testcrossed to vestigial,black males,and the F? progeny were sorted by phenotype and counted.Simple analysis indicates that,on average,18 out of 100 chromosomes recovered from meiosis had a crossover between vg and b.Thus,vg and b are how far apart?

A) 82 centimorgans
B) 82 morgans
C) 18 centimorgans
D) 18 morgans
E) 100 centimorgans

Question 12

Which of the following most accurately represents how Alfred H Sturtevant created the first chromosome map?

A) He used a microscope to view the genes
B) He used a set of microcalipers to measure the distance between the genes on the chromosome
C) He used the data he retrieved from his experimental crosses to determine the distance between the genes on the chromosome
D) All of these
E) None of these

Question 13

The frequency that is often used to measure the degree of linkage between genes is known as the:

A) Linkage frequency
B) Recombination frequency
C) Hardy-Weinberg frequency
D) Genetic frequency
E) Meiosis frequency

Question 14

A frequency of recombination that is less than 50% implies:

A) The genes are linked on the same chromosome
B) The genes are linked on different chromosomes
C) The genes are not linked and are on different chromosomes
D) The genes assort independently
E) The genes are not linked and are on the same chromosome

Question 15

P? blue-flowered,short-stalked plants (++++)and white-flowered,long-stalked plant (ffss).The resulting F? offspring (++fs)are also crossed to produce the following F? progeny: 400 blue,short
400 white,long
100 blu100 white,short e,long
What is the recombination frequency,as shown in the F? generation?

A) 0.25
B) )20
C) )08
D) )10
E) )05

Question 16

You sample a number of cells that have undergone meiosis looking for the production of recombinants between the genes ec,vg,and s.You find 10 cells with no crossovers between ec and s,30 with 1 crossover between ec and s,10 with 2 crossovers between ec and s,and zero with three or more crossovers.What is the map distance between the genes ec and s?

A) 0.2 cM
B) 0.6 cM
C) 0.8 cM
D) 1.0 cM
E) 1.2 cM

Question 17

Which of the following performed experiments in maize that gave the evidence that recombination was caused by a physical exchange of genetic information?

A) Sutton and Boveri
B) McClintock and Creighton
C) Watson and Crick
D) Bateson and Boveri
E) Mendel and Morgan

Question 18

Which of the following is a true statement?

A) Genes that are on the same chromosome should be inherited together
B) Genes that are on the same chromosome proceed through meiosis together
C) Genes that are on different chromosomes are not linked
D) All of these are true
E) None of these are true

Question 19

Linked genes on a chromosome can be mapped by:

A) Determining how often their alleles recombine
B) Determining how many individuals show the wild type phenotype
C) Determining the physical structure of the chromosome
D) Performing a karyotype
E) None of these

Question 20

The distance between two points on the genetic map of a chromosome is equal to:

A) The average number of crossovers between them
B) The exact number of crossovers between them as measured in one cell
C) The estimated number of crossovers between them as measured in one cell
D) None of these
E) All of these

Question 21

Two yeast strains are crossed and,it is observed that there is a very low frequency of nonparental ditype asci.What can you conclude about the genes being studied? 1.The genes are most likely not linked
2)The genes are most likely linked
3)The genes are most likely far apart from each other

A) 1
B) 2
C) 3
D) 2 and 3
E) All of these

Question 22

In a three point test cross there are two gb bt cq progeny and four + bt + progeny out of a hundred progeny,which are the two rarest groups.What can you conclude?

A) The order of the genes is gb cq bt.
B) The 6 progeny are the result of a double crossover.
C) The genes are tightly linked.
D) The order of the genes cannot be determined.
E) The order of the genes is bt gb cq.

Question 23

The basic principle in deletion mapping is that:

A) A deletion that uncovers a recessive mutation must lack a wild-type copy of the mutant gene
B) A deletion that covers a recessive mutation must lack a wild-type copy of the mutant gene
C) A deletion that uncovers a recessive mutation must contain a wild type copy of the mutant gene
D) A deletion that covers a recessive mutation must contain the recessive mutation of the gene
E) All of these

Question 24

In ordered tetrad analysis,what type of pattern occurs when there is a crossover between a locus and the centromere in the first meiotic division?

A) First division segregation
B) Second division segregation
C) Third division segregation
D) Independent assortment
E) Linkage

Question 25

The basic principle in duplication mapping is that:

A) A duplication that covers a recessive mutation must contain a wild-type copy of the mutant gene
B) A duplication that uncovers a recessive mutation must contain a wild type copy of the mutant gene
C) A duplication that covers a recessive mutation must contain the recessive mutation of the gene
D) A duplication that uncovers a recessive mutation must lack a wild type copy of the mutant gene
E) A duplication that covers the recessive mutation must lack a wild type copy of the mutant gene

Question 26

An average of one chiasma during meiosis is equal to how many centiMorgans of genetic distance?

A) 10
B) 20
C) 30
D) 40
E) 50

Question 27

In one type of ascus,two of the ascospores are genotypically like one of the parents and two are like the other parent.An ascus with this pattern is called a:

A) Parental ditype ascus
B) Nonparental ditype ascus
C) Original phenotype ascus
D) Recombinant phenotype ascus
E) None of these

Question 28

Which of the following is a true statement regarding the use of recombination frequencies to estimate genetic distance?

A) It is most accurate when the genes are far apart from one another
B) It is not accurate when the genes are far apart from one another
C) It is not accurate when the genes are close together
D) All of these are true
E) None of these is true

Question 29

In mapping a homozygous recessive mutant with a homozygous deletion in flies:

A) The mutant phenotype will not appear in offspring if the allele lies within the deletion.
B) The wild-type phenotype will always appear if the gene lies within the deletion.
C) The mutant phenotype will always appear in progeny if the gene lies within the deletion.
D) All of these
E) None of these

Question 30

In one type of ascus neither of the two genotypes is like the parental genotypes; thus,the ascus is called a:

A) Parental ditype ascus
B) Nonparental ditype ascus
C) Original phenotype ascus
D) Recombinant phenotype ascus
E) None of these

Question 31

If ascospores are analyzed in the order in which they were created,the fungus must produce spore pairs which are _____________.

A) Unordered tetrads
B) Ordered tetrads
C) Random tetrads
D) Labeled tetrads
E) Allof these

Question 32

Which of the following is a true statement regarding genetic maps and cytological maps?

A) The genetic distance and physical distance on cytological maps are not always uniform
B) Genetic maps and cytological maps are colinear
C) Genetic distances are not proportional to cytological distances
D) All of these are true
E) None of these are true

Question 33

Mapping positions of genes that can be tied to locations on the cytological map of a chromosome is known as:

A) Cytological analysis
B) Cytogenetic mapping
C) Recombination mapping
D) Genetic fingerprinting
E) All of these

Question 34

True genetic distance may be much greater than the observed recombination frequency.Which is not an explanation of this phenomenon?

A) The genes are far apart.
B) Two crossover events may not produce recombinant chromosomes.
C) Four crossover events may not produce recombinant chromosomes.
D) Interference with 2 genes that are tightly linked affects the recombination frequency.
E) A double crossover contributes to the average number of exchanges on a chromosome.

Question 35

Which of the following is a true statement regarding the frequency of crossing over in chromosomes? 1.Crossing over is less likely to occur near the ends of a chromosome
2)Crossing over is less likely to occur near the centromere
3)Crossing over is more likely to occur near the ends of the chromosome

A) 1
B) 2
C) 3
D) 1 and 2
E) 2 and 3

Question 36

A coefficient of coincidence that is equal to 1 implies:

A) That the crossover events are independent
B) That the crossover events are not independent
C) That one crossover event interferes with another crossover event
D) That one crossover event catalyzes another crossover event
E) None of these

Question 37

In a data set to determine crossover frequency between the sc,ec,and cv genes in Drosophila,the crossover frequency between ec and sc = 0.15,and ec and cv = .25.The number of double crossover flies was 15 out of 500 flies.Assuming sc,ec,cv is the respective order of the genes,what can we conclude from this result?

A) The coefficient of coincidence is near zero.
B) The expected number of crossovers and the observed numbers are different.
C) The genes are tightly linked.
D) The coefficient of coincidence is near one.
E) There is a large amount of interference between these genes.

Question 38

Saccharomyces cerevisiae is a good experimental organism for the study of meiosis because:

A) It is haploid with a sexual cycle.
B) It produces 4 ascospores.
C) You can analyze all 4 products of a single meiosis.
D) There are many mutations that have been identified.
E) All of these

Question 39

In this type of ascus there are four kinds of ascospores,one that is like each of the parents and two that are recombinant.

A) Parental ditype ascus
B) Nonparental ditype ascus
C) Tetratype
D) Quadratype
E) Recombinant type ascus

Question 40

A mating between a true breeding red,long-stamen plant with a true breeding,white,short-stamen plant yields an F?.This F? is self fertilized to produce an F? that has 300 red long-stamen plants and 100 white short-stamen plants.What can you conclude? 1.The genes are tightly linked
2)The genes are not tightly linked
3)There were no observable crossover events between the genes

A) 1
B) 2
C) 3
D) 1 and 3
E) 2 and 3

Question 41

In maize,three recessive genes (z,xt,and cm)are linked on chromosome 3.A homozygous plant for the recessives is crossed with a wild-type plant.The F? is crossed to get an F? generation with the following results:

What is the map distance between z and cm ?

Question 42

Which of the following is a true statement regarding inversions and recombination in chromosomes?

A) Inversion typically suppresses recombination
B) The inhibition of crossing over that occurs near the breakpoints of the inversion is compounded by the selective loss of chromosomes that have undergone crossing over within the inverted region.
C) Crossing over is usually inhibited near the breakpoints of a rearrangement in heterozygous condition
D) All of these are true
E) None of these are true

Question 43

Which of the following is true regarding recombination and evolution? 1.Recombination can bring favorable mutations together
2)Chromosome rearrangements can suppress recombination
3)Recombination is under genetic control

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these

Question 44

Some inversion chromosomes are called ____________ because they allow a mutant chromosome to be kept in the heterozygous condition over the inversion.

A) Recombiners
B) Balancers
C) Unbalancers
D) Shufflers
E) None of these

Question 45

In maize,three recessive genes (z,xt,and cm)are linked on chromosome 3.A homozygous plant for the recessives is crossed with a wild-type plant.The F? is crossed to get an F? generation with the following results:

Question 46

In maize,three recessive genes (z,xt,and cm)are linked on chromosome 3.A homozygous plant for the recessives is crossed with a wild-type plant.The F? is crossed to get an F? generation with the following results:

What is the order of the three genes on chromosome 3?

Question 47

An individual with two a?b?c?d?e? chromosomes is crossed with an individual with two a?d?c?b?e? chromosomes.What will happen in the F? during meiosis?

A) Acentric fragments cannot be formed.
B) Acentric fragments cannot be formed.
C) The F? will form many viable gametes.
D) Recombination will be suppressed between the sister chromatids.
E) All of these

Question 48

In order to predict inheritance patterns for human traits,it is necessary to collect data from:

A) Karyotypes
B) Pedigrees
C) Amniocentesis
D) Medical history
E) All of these

Question 49

How would one estimate the genetic map distance between two genes on the same chromosome using the number of crossing over events in a three point cross?

Question 50

150 out of 1000 chromosomes are recombinant between two genes.How far apart are they located on a genetic map?