Question 1

Twin spotting provides evidence of what genetic event?

Accepted Answer

A) meiotic recombination 
B) mitotic recombination 
C) linkage 
D) mutation 
E) biological evolution 
A) meiotic recombination 
B) mitotic recombination 
C) linkage 
D) mutation 
E) biological evolution

Question 2

A dihybrid testcross is made to determine if genes C and D are linked.The results are shown in the table.
 $\begin{array}{|l|c|r|}
\hline \text { Parent genotypes: } & C c  D d \times c c d d & \
\hline & C c  D d & 222 \
\hline & C c  d d & 280 \
\hline \text { Progeny genotypes: } & c c  D d & 280 \
\hline & c c  d d & 218 \
\hline & & 1000 \
\hline
\end{array}$  
-The chi-square value is the sum for all progeny classes of (observed-expected)2/expected.Using the chi-square test for goodness of fit, calculate the chi-square value to test the null hypothesis that genes C and D are unlinked.What is the chi-square value?

Accepted Answer

A) 0 
B) 0.0576 
C) 10.8 
D) 14.4 
E) cannot be determined 
A) 0 
B) 0.0576 
C) 10.8 
D) 14.4 
E) cannot be determined

Question 3

If only 100 progeny had been counted and the same proportions of progeny genotypes observed, how would the p value and the conclusion drawn about linkage change?

Accepted Answer

A) The p value would increase, and the likelihood of linkage decreases. 
B) The p value would decrease, and the likelihood of linkage increases. 
C) Neither the p value nor the likelihood of linkage would change. 
D) The p value would decrease, and the likelihood of linkage decreases. 
A) The p value would increase, and the likelihood of linkage decreases. 
B) The p value would decrease, and the likelihood of linkage increases. 
C) Neither the p value nor the likelihood of linkage would change. 
D) The p value would decrease, and the likelihood of linkage decreases.

Question 4

In Drosophila, the autosomal recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have brick-red eyes).Flies who are homozygous recessive at both pr and cn have orange eyes.A female who has wild-type eyes is crossed to an orange-eyed male.Their progeny have the following distribution of eye colors:
 $$\begin{array} { | l | r | } 
\hline \text { wild-type } & \text { 8 } \
\hline \text { brown } & 241 \
\hline \text { briphit-red } & 239 \
\hline \text { orarnge } & \underline{12} \
\hline & 500 \
\hline
\end{array}$$
-What is the genotype of the wild-type mother of these progeny?

Accepted Answer

A) pr cn / pr+ cn+ 
B) pr+ cn / pr+ cn 
C) pr+ cn / pr cn+ 
D) pr cn+ / pr cn+ 
E) pr cn / pr cn 
A) pr cn / pr+ cn+ 
B) pr+ cn / pr+ cn 
C) pr+ cn / pr cn+ 
D) pr cn+ / pr cn+ 
E) pr cn / pr cn

Question 5

Crossing-over takes place in bivalents (tetrads)consisting of ________ chromatids, and one crossover involves ________ chromatids.

Accepted Answer

A) 2; 2 
B) 2; 4 
C) 4; 2 
D) 4; 4 
E) 8; 4 
A) 2; 2 
B) 2; 4 
C) 4; 2 
D) 4; 4 
E) 8; 4

Question 6

Tetrad analysis shows that crossing-over occurs at the four-strand stage (i.e. , after replication)because, when two genes are linked,

Accepted Answer

A) NPD > T. 
B) T > NPD. 
C) T > PD. 
D) PD > NPD. 
E) PD > T. 
A) NPD > T. 
B) T > NPD. 
C) T > PD. 
D) PD > NPD. 
E) PD > T.

Question 7

Suppose the map for a particular human chromosome interval is:
 a——1 m.u.——b--1 m.u.——c--1 m.u.——d——1 m.u.——e——1 m.u.——f
In a man heterozygous for all six genes, what fraction of his sperm would be recombinant in the a-f interval?

Accepted Answer

A) 0% 
B) 1% 
C) 2.5% 
D) 5% 
E) cannot be determined 
A) 0% 
B) 1% 
C) 2.5% 
D) 5% 
E) cannot be determined

Question 8

Sectors with a different phenotype in an otherwise uniform yeast colony may be evidence of mitotic recombination.

Accepted Answer

A) True 
 B)False

Question 9

Suppose a three-point testcross was conducted involving genes X, Y, and Z.If the most abundant classes of progeny are X Y z and x y Z and the rarest classes are x Y Z and X y z, which gene is in the middle?

Accepted Answer

A) X 
B) Y 
C) Z 
D) cannot be determined 
A) X 
B) Y 
C) Z 
D) cannot be determined

Question 10

A haploid yeast strain has mating type a and genotype his4 TRP1. A different haploid yeast strain has mating type ? and genotype HIS4 trp1. The two strains mate and produce diploid offspring with genotype his4 TRP1 / HIS4 trp1. The diploid cells undergo meiosis to produce a variety of tetrad types. In the following questions, the genotypes of the spores in a tetrad are shown. For each tetrad, tell what type it is: parental (PD), non-parental (NPD), or tetratype (T).
-HIS4 trp1; HIS4 TRP1; his4 TRP1; his4 trp1?

Accepted Answer

A) PD 
B) NPD 
C) T 
D) cannot be determined 
A) PD 
B) NPD 
C) T 
D) cannot be determined

Question 11

n Drosophila, the autosomal recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have brick-red eyes).Flies who are homozygous recessive at both pr and cn have orange eyes.A female who has wild-type eyes is crossed to an orange-eyed male.Their progeny have the following distribution of eye colors:
 $$\begin{array} { | l | r | } 
\hline \text { wild-type } & \text { 8 } \
\hline \text { brown } & 241 \
\hline \text { briphit-red } & 239 \
\hline \text { orarnge } & \underline{12} \
\hline & 500 \
\hline
\end{array}$$
-What is the map distance between the pr and cn genes?

Accepted Answer

A) 20 m.u. 
B) 2 m.u. 
C) 4 m.u. 
D) 46 m.u. 
E) 8 m.u. 
A) 20 m.u. 
B) 2 m.u. 
C) 4 m.u. 
D) 46 m.u. 
E) 8 m.u.

Question 12

A linkage group includes all of the genes on a chromosome, including genes that are so far apart from each other on a chromosome that they assort independently during meiosis.

Accepted Answer

A) True 
 B)False

Question 13

Which process(es)can generate recombinant gametes? (Select all that apply. )

Accepted Answer

A) crossing-over between two linked heterozygous loci 
B) independent assortment of two unlinked heterozygous loci 
C) segregation of alleles in a homozygote 
D) crossing-over between two linked homozygous loci 
A) crossing-over between two linked heterozygous loci 
B) independent assortment of two unlinked heterozygous loci 
C) segregation of alleles in a homozygote 
D) crossing-over between two linked homozygous loci

Question 14

In Neurospora, the white-spore allele (ws) results in white spores rather than the wild-type black spores. Diploid ws / ws+ cells undergo meiosis followed by one round of mitosis to form ordered tetrads. Indicate if the pattern of spores seen in the tetrads are consistent with first-division or second-division segregation.
-ws; ws; ws; ws; ws+; ws+; ws+; ws+

Accepted Answer

A) first-division segregation pattern 
B) second-division segregation pattern 
A) first-division segregation pattern 
B) second-division segregation pattern

Question 15

In Drosophila, the genes b, c, and sp are linked and arranged as shown below: b--30 m.u.--c--20 m.u.--sp
This region exhibits 90% interference.How many double crossovers would be recovered in a three-point cross involving b, c, and sp out of 1000 progeny?

Accepted Answer

A) 3 
B) 6 
C) 54 
D) 60 
E) 600 
A) 3 
B) 6 
C) 54 
D) 60 
E) 600

Question 16

In Drosophila, the genes y, f, and v are all X-linked. Females who are homozygous for recessive alleles of all three genes (y f v / y f v) are crossed to wild-type males. The resulting trihybrid F1 females are testcrossed. The F2 are distributed as follows:

$$\begin{array} { | l | r | } 
\hline y f v & 3210 \
\hline y f v ^ { + } & 72 \
\hline y f ^ { + } v & 1024 \
\hline y f ^ { + } v^ + & 678 \
\hline y ^ { + } f v & 690 \
\hline y ^ { + } f v ^+ & 1044 \
\hline y ^ { + } f ^+ v & 60 \
\hline y ^ { + } f ^+ v^ + & 3222 \
\hline & 10,000 \
\hline
\end{array}$$

-Which of the following linkage maps correctly shows the order and distance between the y, f, and v genes?

Accepted Answer

A) f--35 m.u.--y--15 m.u.--v 
B) f--22 m.u.--y--15 m.u.--v 
C) y--35 m.u.--f--22 m.u.--v 
D) y--22 m.u.--v--15 m.u.--f 
E) y--15 m.u.--v--22 m.u.--f 
A) f--35 m.u.--y--15 m.u.--v 
B) f--22 m.u.--y--15 m.u.--v 
C) y--35 m.u.--f--22 m.u.--v 
D) y--22 m.u.--v--15 m.u.--f 
E) y--15 m.u.--v--22 m.u.--f

Question 17

A haploid yeast strain has mating type a and genotype his4 TRP1. A different haploid yeast strain has mating type ? and genotype HIS4 trp1. The two strains mate and produce diploid offspring with genotype his4 TRP1 / HIS4 trp1. The diploid cells undergo meiosis to produce a variety of tetrad types. In the following questions, the genotypes of the spores in a tetrad are shown. For each tetrad, tell what type it is: parental (PD), non-parental (NPD), or tetratype (T).
-his4 trp1; his4 trp1; HIS4 TRP1; HIS4 TRP?

Accepted Answer

A) PD 
B) NPD 
C) T 
D) cannot be determined 
A) PD 
B) NPD 
C) T 
D) cannot be determined

Question 18

The zipper-like connection between paired homologs in early prophase is known as a

Accepted Answer

A) spindle fiber. 
B) synaptic junction. 
C) synaptonemal complex. 
D) chiasma. 
E) None of the choices is correct. 
A) spindle fiber. 
B) synaptic junction. 
C) synaptonemal complex. 
D) chiasma. 
E) None of the choices is correct.

Question 19

Females heterozygous for the recessive second chromosome mutations px, sp, and cn are mated to a male homozygous for all three mutations.The offspring are as follows:
 $\begin{array}{|l|r|}
\hline p x  s p  c n & 1461 \
\hline p x  s p  c n^{+} & 3497 \
\hline p x  s p{+ c n} & 1\
\hline p x  s p^{+}  c n+ & 11 \
\hline p x^{+}  s p  c n & 9 \
\hline p x^{+}  s p  c n+ & 0 \
\hline p x^{+}  s p+ c n & 3483 \
\hline p x^{+}  s p+ c n+ & 1539 \
\hline & 10,000 \
\hline
\end{array}$
-What is the genotype of the females that gave rise to these progeny?

Accepted Answer

A) px+ sp cn / px sp+ cn+ 
B) px+ sp cn+ / px sp+ cn 
C) px+ sp+ cn+ / px sp cn 
D) px sp cn+ / px+ sp+ cn 
E) insufficient data 
A) px+ sp cn / px sp+ cn+ 
B) px+ sp cn+ / px sp+ cn 
C) px+ sp+ cn+ / px sp cn 
D) px sp cn+ / px+ sp+ cn 
E) insufficient data

Question 20

If the p value corresponding to a given χ2 value and number of degrees of freedom is lower than 0.05, then the null hypothesis is rejected and it can be said with some confidence that the two genes being evaluated are linked.

Accepted Answer

A) True 
 B)False

Twin spotting provides evidence of what genetic event?

If only 100 progeny had been counted and the same proportions of progeny genotypes observed, how would the p value and the conclusion drawn about linkage change?

Crossing-over takes place in bivalents (tetrads)consisting of chromatids, and one crossover involves chromatids.

Tetrad analysis shows that crossing-over occurs at the four-strand stage (i.e. , after replication)because, when two genes are linked,

Suppose the map for a particular human chromosome interval is: a——1 m.u.——b--1 m.u.——c--1 m.u.——d——1 m.u.——e——1 m.u.——f In a man heterozygous for all six genes, what fraction of his sperm would be recombinant in the a-f interval?

Sectors with a different phenotype in an otherwise uniform yeast colony may be evidence of mitotic recombination.

Suppose a three-point testcross was conducted involving genes X, Y, and Z.If the most abundant classes of progeny are X Y z and x y Z and the rarest classes are x Y Z and X y z, which gene is in the middle?

A linkage group includes all of the genes on a chromosome, including genes that are so far apart from each other on a chromosome that they assort independently during meiosis.

Which process(es)can generate recombinant gametes? (Select all that apply. )

In Drosophila, the genes b, c, and sp are linked and arranged as shown below: b--30 m.u.--c--20 m.u.--sp This region exhibits 90% interference.How many double crossovers would be recovered in a three-point cross involving b, c, and sp out of 1000 progeny?

The zipper-like connection between paired homologs in early prophase is known as a

If the p value corresponding to a given χ² value and number of degrees of freedom is lower than 0.05, then the null hypothesis is rejected and it can be said with some confidence that the two genes being evaluated are linked.

Genetics: the Study of Biological Information

Mendels Principles of Heredity

Extensions to Mendels Laws

The Chromosome Theory of Inheritance

DNA Structure, Replication, and Recombination

Anatomy and Function of a Gene: Dissection Through Mutation

Gene Expression: the Flow of Information From Dna to Rna to Protein

Digital Analysis of Dna

Genome Annotation

Analyzing Genomic Variation

The Eukaryotic Chromosome

Chromosomal Rearrangements and Changes in Chromosome Number

Bacterial Genetics

Organellar Inheritance

Gene Regulation in Prokaryotes

Gene Regulation in Eukaryotes

Manipulating the Genomes of Eukaryotes

The Genetic Analysis of Development

The Genetics of Cancer

Variation and Selection in Populations

The Genetics of Complex Traits

Filters

Exam 5: Linkage, Recombination, and the Mapping of Genes on Chromosomes

Twin spotting provides evidence of what genetic event?

If only 100 progeny had been counted and the same proportions of progeny genotypes observed, how would the p value and the conclusion drawn about linkage change?

Crossing-over takes place in bivalents (tetrads)consisting of ________ chromatids, and one crossover involves ________ chromatids.

Tetrad analysis shows that crossing-over occurs at the four-strand stage (i.e. , after replication)because, when two genes are linked,

Suppose the map for a particular human chromosome interval is: a——1 m.u.——b--1 m.u.——c--1 m.u.——d——1 m.u.——e——1 m.u.——f In a man heterozygous for all six genes, what fraction of his sperm would be recombinant in the a-f interval?

Sectors with a different phenotype in an otherwise uniform yeast colony may be evidence of mitotic recombination.

Suppose a three-point testcross was conducted involving genes X, Y, and Z.If the most abundant classes of progeny are X Y z and x y Z and the rarest classes are x Y Z and X y z, which gene is in the middle?

A linkage group includes all of the genes on a chromosome, including genes that are so far apart from each other on a chromosome that they assort independently during meiosis.

Which process(es)can generate recombinant gametes? (Select all that apply. )

In Drosophila, the genes b, c, and sp are linked and arranged as shown below: b--30 m.u.--c--20 m.u.--sp This region exhibits 90% interference.How many double crossovers would be recovered in a three-point cross involving b, c, and sp out of 1000 progeny?

The zipper-like connection between paired homologs in early prophase is known as a

If the p value corresponding to a given χ2 value and number of degrees of freedom is lower than 0.05, then the null hypothesis is rejected and it can be said with some confidence that the two genes being evaluated are linked.

Genetics: the Study of Biological Information

Mendels Principles of Heredity

Extensions to Mendels Laws

The Chromosome Theory of Inheritance

DNA Structure, Replication, and Recombination

Anatomy and Function of a Gene: Dissection Through Mutation

Gene Expression: the Flow of Information From Dna to Rna to Protein

Digital Analysis of Dna

Genome Annotation

Analyzing Genomic Variation

The Eukaryotic Chromosome

Chromosomal Rearrangements and Changes in Chromosome Number

Bacterial Genetics

Organellar Inheritance

Gene Regulation in Prokaryotes

Gene Regulation in Eukaryotes

Manipulating the Genomes of Eukaryotes

The Genetic Analysis of Development

The Genetics of Cancer

Variation and Selection in Populations

The Genetics of Complex Traits

Filters

Crossing-over takes place in bivalents (tetrads)consisting of chromatids, and one crossover involves chromatids.

If the p value corresponding to a given χ² value and number of degrees of freedom is lower than 0.05, then the null hypothesis is rejected and it can be said with some confidence that the two genes being evaluated are linked.