Question 1

At what stage of the meiotic cell cycle and during what chromosomal configuration does crossing over occur?

Accepted Answer

A) during synapsis in prometaphase 
B) at the four-strand stage of meiosis,after synapsis of homologous chromosomes,and before the end of prophase I 
C) in S phase of meiosis 
D) during synapsis at the four-strand stage of meiosis 
E) during bivalent formation,after synapsis of homologous chromosomes,and before the end of prophase I 
A) during synapsis in prometaphase 
B) at the four-strand stage of meiosis,after synapsis of homologous chromosomes,and before the end of prophase I 
C) in S phase of meiosis 
D) during synapsis at the four-strand stage of meiosis 
E) during bivalent formation,after synapsis of homologous chromosomes,and before the end of prophase I

Question 2

Which of the following scenarios would erroneously lead you to believe two genes reside on different chromosomes when they in fact are on the same chromosome?

Accepted Answer

A) the genes are very far apart on the same chromosome,such that there is always a crossover between them 
B) the genes are very close together on the chromosome,such that there is never a crossover between them 
C) too large a sample size 
D) the genes are very far apart on the same chromosome,such that there is never a crossover between them 
E) a mating between consanguineous individuals 
A) the genes are very far apart on the same chromosome,such that there is always a crossover between them 
B) the genes are very close together on the chromosome,such that there is never a crossover between them 
C) too large a sample size 
D) the genes are very far apart on the same chromosome,such that there is never a crossover between them 
E) a mating between consanguineous individuals

Question 3

What is a physical map of a chromosome?

Accepted Answer

A) identification of the length of the chromosome by comparing it to known chromosomes 
B) description of the base pair difference between two loci 
C) determination of the p and q arm length 
D) determination of where the centromere lies 
E) determination of how far apart genes are my recombination mapping 
A) identification of the length of the chromosome by comparing it to known chromosomes 
B) description of the base pair difference between two loci 
C) determination of the p and q arm length 
D) determination of where the centromere lies 
E) determination of how far apart genes are my recombination mapping

Question 4

Phenotypically wild-type F1 female Drosophila,whose mothers had light eyes lt and fathers had straw stw bristles,produced the following offspring when crossed to homozygous light-straw males:   Compute the map distance between the light and straw loci.

Accepted Answer

A) 4 map units 
B) 98 map units 
C) 12 map units 
D) 8 map units 
E) 2 map units 
A) 4 map units 
B) 98 map units 
C) 12 map units 
D) 8 map units 
E) 2 map units

Question 5

Assume that a cross is made between AaBb and aabb plants and that the offspring fall into approximately equal numbers of the following groups: AaBb,Aabb,aaBb,aabb.These results are consistent with which of the following?

Accepted Answer

A) alternation of generations 
B) incomplete dominance 
C) hemizygosity 
D) independent assortment 
E) complete linkage 
A) alternation of generations 
B) incomplete dominance 
C) hemizygosity 
D) independent assortment 
E) complete linkage

Question 6

Assume that two genes are 80 map units apart on chromosome II of Drosophila and that a cross is made between a doubly heterozygous female and a homozygous recessive male.What percent recombination would be expected in the offspring of this type of cross?

Accepted Answer

A) 30 
B) 5 
C) 50 
D) 100 
E) 80 
A) 30 
B) 5 
C) 50 
D) 100 
E) 80

Question 7

In the fruit fly,Drosophila melanogaster,a spineless no wing bristles female fly is mated to a male that is claret dark eyes and hairless no thoracic bristles .Phenotypically wild-type FS1U1B11 S1U1B0female progeny were mated to fully homozygous mutant males,and the following progeny 1000 total were observed:  
- 
What are the map distances between hairless and spineless?

Accepted Answer

A) 50 
B) 10 
C) 40 
D) 30 
E) 45 
A) 50 
B) 10 
C) 40 
D) 30 
E) 45

Question 8

Which of the following is an example of positive interference?

Accepted Answer

A) Double crossovers do not occur. 
B) A single crossover stimulates further recombination. 
C) Crossovers will not occur near centromeres. 
D) An actively transcribed gene is less likely to undergo crossover than a quiescent one. 
E) A crossover in one region inhibits crossovers in nearby regions. 
A) Double crossovers do not occur. 
B) A single crossover stimulates further recombination. 
C) Crossovers will not occur near centromeres. 
D) An actively transcribed gene is less likely to undergo crossover than a quiescent one. 
E) A crossover in one region inhibits crossovers in nearby regions.

Question 9

Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb,48 Aabb,52 aaBb,94 aabb.These results are consistent with which of the following?

Accepted Answer

A) sex-linked inheritance with 30% crossing over 
B) independent assortment 
C) linkage with approximately 33 map units between the two gene loci 
D) 100% recombination 
E) linkage with 50% crossing over 
A) sex-linked inheritance with 30% crossing over 
B) independent assortment 
C) linkage with approximately 33 map units between the two gene loci 
D) 100% recombination 
E) linkage with 50% crossing over

Question 10

If complete linkage occurs,we expect ______.

Accepted Answer

A) to see all four types of offspring 
B) a 1:1:1:1 ratio in the test cross 
C) to see only parental phenotypes in the F2 of the appropriate test cross 
D) to see only recombinant phenotypes in the F2 of the appropriate test cross 
E) a 9:3:3:1 ratio in the F2 
A) to see all four types of offspring 
B) a 1:1:1:1 ratio in the test cross 
C) to see only parental phenotypes in the F2 of the appropriate test cross 
D) to see only recombinant phenotypes in the F2 of the appropriate test cross 
E) a 9:3:3:1 ratio in the F2

Question 11

In the fruit fly,Drosophila melanogaster,a spineless no wing bristles female fly is mated to a male that is claret dark eyes and hairless no thoracic bristles).Phenotypically wild-type FS1U1B11 S1U1B0female progeny were mated to fully homozygous mutant males,and the following progeny 1000 total were observed:  
-
What is the gene order?

Accepted Answer

A) spineless,claret,hairless 
B) claret,hairless,spineless 
C) it is impossible to tell 
D) claret,spineless,hairless 
E) hairless,spineless,claret 
A) spineless,claret,hairless 
B) claret,hairless,spineless 
C) it is impossible to tell 
D) claret,spineless,hairless 
E) hairless,spineless,claret

Question 12

The cross GE/ge × ge/ge produces the following progeny: GE/ge 404; ge/ge 396; gE/ge 97; Ge/ge 103.From these data,one can conclude that there are map units between the G and E loci.

Accepted Answer

A) 15 
B) 25 
C) 10 
D) 5 
E) 20 
A) 15 
B) 25 
C) 10 
D) 5 
E) 20

Question 13

What is the relationship between the degree of crossing over and the distance between two genes?

Accepted Answer

A) There is no correlation. 
B) It is direct: as the distance decreases,the frequency of recombination increases. 
C) It is indirect: as the distance decreases,the frequency of recombination doubles. 
D) It is indirect: as the distance increases,the frequency of recombination doubles. 
E) It is direct: as the distance increases,the frequency of recombination increases. 
A) There is no correlation. 
B) It is direct: as the distance decreases,the frequency of recombination increases. 
C) It is indirect: as the distance decreases,the frequency of recombination doubles. 
D) It is indirect: as the distance increases,the frequency of recombination doubles. 
E) It is direct: as the distance increases,the frequency of recombination increases.

Question 14

Assume that investigators crossed a strain of flies carrying the dominant eye mutation Lobe on the second chromosome with a strain homozygous for the second chromosome recessive mutations smooth abdomen and straw body.The F1 Lobe females were then backcrossed with homozygous smooth abdomen,straw body males,the following phenotypes were observed:

Accepted Answer

A) smooth,Lobe,straw 
B) it is impossible to tell 
C) Lobe,smooth,straw 
D) smooth,straw,Lobe 
E) Lobe,straw,smooth 
A) smooth,Lobe,straw 
B) it is impossible to tell 
C) Lobe,smooth,straw 
D) smooth,straw,Lobe 
E) Lobe,straw,smooth

Question 15

What two terms apply to the fusion of cultured human and mouse cells that produces cell lines that are useful in assigning a gene to a particular human chromosome?

Accepted Answer

A) forward and reverse 
B) lod score and pod score 
C) positive and negative 
D) single and double 
E) heterokaryon and synkaryon 
A) forward and reverse 
B) lod score and pod score 
C) positive and negative 
D) single and double 
E) heterokaryon and synkaryon

Question 16

Choose the true statement below.

Accepted Answer

A) When two genes are over 50 map units apart,a crossover can theoretically occur 100% of the time. 
B) The percentage of tetrads involved in exchange between two genes is equal to the number of recombinant progeny seen. 
C) Linkage viewed from results of typical crosses always occurs when two loci are on the same chromosome. 
D) When two genes are over 50 map units apart,a crossover would theoretically occur 0% of the time. 
E) A single crossover on a chromosome will always yield the recombinant phenotype of the genes you are interested in. 
A) When two genes are over 50 map units apart,a crossover can theoretically occur 100% of the time. 
B) The percentage of tetrads involved in exchange between two genes is equal to the number of recombinant progeny seen. 
C) Linkage viewed from results of typical crosses always occurs when two loci are on the same chromosome. 
D) When two genes are over 50 map units apart,a crossover would theoretically occur 0% of the time. 
E) A single crossover on a chromosome will always yield the recombinant phenotype of the genes you are interested in.

Question 17

Who was the student in Morgan's laboratory who first realized that the sequence of genes could be determined by Morgan's proposal that two genes located relatively close to each other are less likely to form chiasma between them than if the two genes were relatively far apart?

Accepted Answer

A) Charles Darwin 
B) Barbara McClintock 
C) Thomas Hunt 
D) 
A) H.Sturtevant 
E) Gregor Mendel 
A) Charles Darwin 
B) Barbara McClintock 
C) Thomas Hunt 
D) 
A) H.Sturtevant 
E) Gregor Mendel

Question 18

Three loci,mitochondrial malate dehydrogenase that forms a and b MDHa,MDHb ,glucuronidase that forms 1 and 2 GUS1,GUS2 ,and a histone gene that forms + and - H+,H- ,are located on chromosome #7 in humans.Assume that the MDH locus is at position 35,GUS at position 45,and H at position 75.A female whose mother was homozygous for MDHa,GUS2,and H+ and whose father was homozygous for MDHb,GUS1,and H- produces a sample of 1000 egg cells.Give the expected numbers of the MDHa GUS2 H- cells she would produce.Assume no chromosomal interference.

Accepted Answer

A) 15 
B) 235 
C) 315 
D) 135 
E) 0 
A) 15 
B) 235 
C) 315 
D) 135 
E) 0

Question 19

Which of the following statements is true?

Accepted Answer

A) The linkage ratio is best seen in genes on nonhomologous chromosomes. 
B) If two gene loci are on nonhomologous chromosomes,genes at these loci are expected to assort independently. 
C) Linkage without crossing over leads to all recombinant chromosomes. 
D) The chromosomal theory of inheritance denotes that linked alleles will never be separated. 
E) A centromere and its surrounding genes constitute a linkage group. 
A) The linkage ratio is best seen in genes on nonhomologous chromosomes. 
B) If two gene loci are on nonhomologous chromosomes,genes at these loci are expected to assort independently. 
C) Linkage without crossing over leads to all recombinant chromosomes. 
D) The chromosomal theory of inheritance denotes that linked alleles will never be separated. 
E) A centromere and its surrounding genes constitute a linkage group.

Question 20

What is a lod score?

Accepted Answer

A) determination of the probability that two traits are linked by analyzing pedigrees 
B) determination of how often a gene mapping experiment gives the correct results 
C) a method using cell fusion to determine on which chromosome a gene resides 
D) a calculation to show how much interference is occurring in crossover formation 
E) determination of how often double crossovers occur 
A) determination of the probability that two traits are linked by analyzing pedigrees 
B) determination of how often a gene mapping experiment gives the correct results 
C) a method using cell fusion to determine on which chromosome a gene resides 
D) a calculation to show how much interference is occurring in crossover formation 
E) determination of how often double crossovers occur

Exam 5: Chromosome Mapping in Eukaryotes

At what stage of the meiotic cell cycle and during what chromosomal configuration does crossing over occur?

Which of the following scenarios would erroneously lead you to believe two genes reside on different chromosomes when they in fact are on the same chromosome?

What is a physical map of a chromosome?

Phenotypically wild-type F1 female Drosophila,whose mothers had light eyes lt and fathers had straw stw bristles,produced the following offspring when crossed to homozygous light-straw males: Compute the map distance between the light and straw loci.

Assume that a cross is made between AaBb and aabb plants and that the offspring fall into approximately equal numbers of the following groups: AaBb,Aabb,aaBb,aabb.These results are consistent with which of the following?

Assume that two genes are 80 map units apart on chromosome II of Drosophila and that a cross is made between a doubly heterozygous female and a homozygous recessive male.What percent recombination would be expected in the offspring of this type of cross?

Which of the following is an example of positive interference?

Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb,48 Aabb,52 aaBb,94 aabb.These results are consistent with which of the following?

If complete linkage occurs,we expect ______.

The cross GE/ge × ge/ge produces the following progeny: GE/ge 404; ge/ge 396; gE/ge 97; Ge/ge 103.From these data,one can conclude that there are map units between the G and E loci.

What is the relationship between the degree of crossing over and the distance between two genes?

What two terms apply to the fusion of cultured human and mouse cells that produces cell lines that are useful in assigning a gene to a particular human chromosome?

Choose the true statement below.

Who was the student in Morgan's laboratory who first realized that the sequence of genes could be determined by Morgan's proposal that two genes located relatively close to each other are less likely to form chiasma between them than if the two genes were relatively far apart?

Which of the following statements is true?

What is a lod score?

Introduction to Genetics

Mitosis and Meiosis

Mendelian Genetics

Extensions of Mendelian Genetics

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Sex Determination and Sex Chromosomes

Chromosome Mutations: Variation in Number and Arrangement

Extranuclear Inheritance

DNA Structure and Analysis

DNA Replication and Recombination

DNA Organization in Chromosomes

The Genetic Code and Transcription

Translation and Proteins

Gene Mutation,dna Repair,and Transposition

Regulation of Gene Expression in Bacteria

Transcriptional Regulation in Eukaryotes

Post-Transcriptional Regulation in Eukaryotes

Epigenetic Regulation in Eukaryotes

Recombinant Dna Technology

Genomic Analysis

Applications of Genetic Engineering and Biotechnology

Developmental Genetics

Cancer Genetics

Quantitative Genetics and Multifactorial Traits

Population and Evolutionary Genetics

CRISPR and Genomic Editing

DNA Forensics

Genomics and Precision Medicine

Genetically Modified Foods

Gene Therapy

Advances in Neurogenetics: The Study of Huntington Disease

Filters

Phenotypically wild-type F₁female Drosophila,whose mothers had light eyes lt and fathers had straw stw bristles,produced the following offspring when crossed to homozygous light-straw males: Compute the map distance between the light and straw loci.