Question 1

What is the purpose of DNA supercoiling?

Accepted Answer

nucleoid chromosomal compaction

Question 2

How might a thermophilic bacterium use chromosome structure to protect against heat-induced DNA degradation?

Accepted Answer

A) It expresses excess amounts of SMC proteins that allow the DNA to more tightly condense during periods of high heat. 
B) It can express a specialized topoisomerase that induces negative supercoiling, which provides additional chromosomal stability. 
C) It expresses a specialized topoisomerase that induces positive supercoiling, which provides additional chromosomal stability. 
D) It expresses enzymes that inhibit topoisomerase during high heat, which prevents DNA from unwinding and becoming susceptible to heat degradation. 
E) It expresses helicase, an enzyme that nicks the DNA helix and allows it to assume a more stable conformation and thus to resist heat-induced degradation. 
A) It expresses excess amounts of SMC proteins that allow the DNA to more tightly condense during periods of high heat. 
B) It can express a specialized topoisomerase that induces negative supercoiling, which provides additional chromosomal stability. 
C) It expresses a specialized topoisomerase that induces positive supercoiling, which provides additional chromosomal stability. 
D) It expresses enzymes that inhibit topoisomerase during high heat, which prevents DNA from unwinding and becoming susceptible to heat degradation. 
E) It expresses helicase, an enzyme that nicks the DNA helix and allows it to assume a more stable conformation and thus to resist heat-induced degradation. C

Question 3

If heterochromatic spreading encompasses the new location of the w+ gene, what phenotype will the cells have?

Accepted Answer

white eyes

Question 4

What molecular interaction allows histones to interact with DNA?

Accepted Answer

positive c

Question 5

A bacterium inherits a mutation that renders its topoisomerase enzyme nonfunctional. What phenotype would you expect to see in this bacterium?

Accepted Answer

A) The cell would accumulate broken DNA because overwinding cannot be corrected, so the cell would be unable to replicate and would die. 
B) The cell would accumulate supercoiled DNA, but otherwise it would be perfectly normal. 
C) The cell would accumulate relaxed DNA, which would make DNA replication and cell division highly disorganized and lead to cell death. 
D) The cell would accumulate relaxed DNA, but otherwise it would be perfectly normal. 
E) The cell would be unaffected because bacteria have many different topoisomerases that are involved in replication. 
A) The cell would accumulate broken DNA because overwinding cannot be corrected, so the cell would be unable to replicate and would die. 
B) The cell would accumulate supercoiled DNA, but otherwise it would be perfectly normal. 
C) The cell would accumulate relaxed DNA, which would make DNA replication and cell division highly disorganized and lead to cell death. 
D) The cell would accumulate relaxed DNA, but otherwise it would be perfectly normal. 
E) The cell would be unaffected because bacteria have many different topoisomerases that are involved in replication.

Question 6

Active transcription occurs in regions of chromatin loops that are located __________.

Accepted Answer

A) near the MARS 
B) a large distance away from the MARS 
C) within the linker DNA 
D) within the telomeres 
E) within the euchromatin and constitutive heterochromatin 
A) near the MARS 
B) a large distance away from the MARS 
C) within the linker DNA 
D) within the telomeres 
E) within the euchromatin and constitutive heterochromatin

Question 7

Nucleosomes are comprised of how many molecules of histones?

Accepted Answer

The answer of Nucleosomes are comprised of how many molecules...

Question 8

What is the diameter of a nucleosome?

Accepted Answer

The answer of What is the diameter of a nucleosome?...

Question 9

You are trying to prepare a DNA karyotype, but this time you forgot to add trypsin to your chromosome preparation. What effect would you expect to see?

Accepted Answer

A) Dyes would stain the chromosomes darker because more proteins would be present to take up the dye. 
B) Dyes would not stain the chromosomes as expected because proteins would not be removed from the chromatin and so would block the dye from accessing the DNA. 
C) Chromosomes would not condense properly, so it would be very difficult to isolate individual chromosomes. 
D) Chromosomes would be degraded quickly because the trypsin is necessary to promote DNA stability by adding more scaffold proteins to the chromatin. 
E) The chromosomes would be more difficult to pair up because the trypsin acts as a dye, creating a banding pattern that distinguishes between chromosomes. 
A) Dyes would stain the chromosomes darker because more proteins would be present to take up the dye. 
B) Dyes would not stain the chromosomes as expected because proteins would not be removed from the chromatin and so would block the dye from accessing the DNA. 
C) Chromosomes would not condense properly, so it would be very difficult to isolate individual chromosomes. 
D) Chromosomes would be degraded quickly because the trypsin is necessary to promote DNA stability by adding more scaffold proteins to the chromatin. 
E) The chromosomes would be more difficult to pair up because the trypsin acts as a dye, creating a banding pattern that distinguishes between chromosomes.

Question 10

Histone proteins are the principal agents in chromatin packaging. The nucleosome core particle is a heterooctameric protein complex that contains two molecules each of the four histones H2A, H2B, H3, and H4. Describe the process of managing existing nucleosome core particles during replication and the process of adding these and new nucleosome core particles to DNA after the replication
fork passes.

Accepted Answer

The assembly of nucleosome core particle

Question 11

If you want to prevent chromatin loops from being anchored to the chromosome scaffold, which regions of the DNA would you target?

Accepted Answer

MARS (matr

Question 12

Under normal cellular conditions, what is the diameter of the chromatin as it forms the solenoid structure?

Accepted Answer

A) 3 nm 
B) 10 nm 
C) 30 nm 
D) 34 nm 
E) 100 nm 
A) 3 nm 
B) 10 nm 
C) 30 nm 
D) 34 nm 
E) 100 nm

Question 13

Quinolones are a group of broad-spectrum antibiotics that specifically target topoisomerase. Explain how this contributes to cell death in bacteria. Would you expect these drugs to kill hyperthermophilic prokaryotes too? Why or why not?

Accepted Answer

Supercoiled DNA exists naturally in circ

Question 14

Karyotypes are a method for displaying chromosomes by grouping them into homologous pairs based on what two distinguishing factors?

Accepted Answer

size and b

Question 15

Archaea have histone proteins that are homologous to the histone proteins found in eukaryotes. Thus far, available evidence indicates that archaeal histone proteins play a role in which function?

Accepted Answer

The answer of Archaea have histone proteins that are homologous...

Question 16

The flies with variegated eye color had what abnormal chromosome structure?

Accepted Answer

A) X-chromosome inversion that moves the w+ gene to a different orientation on the chromosome in some cells following X-ray exposure 
B) X-chromosome translocation that moves the w+ gene to a region of heterochromatin on another chromosome in some cells following X-ray exposure 
C) a mutation in the w+ gene following X-ray exposure that causes the gene to be overexpressed in a tissue-specific manner 
D) X-chromosome deletion that deleted the w+ gene in some cells following X-ray exposure 
E) a mutation in a somatic chromosome that causes the w+ gene to be translocated to the X-chromosomes following X-ray exposure 
A) X-chromosome inversion that moves the w+ gene to a different orientation on the chromosome in some cells following X-ray exposure 
B) X-chromosome translocation that moves the w+ gene to a region of heterochromatin on another chromosome in some cells following X-ray exposure 
C) a mutation in the w+ gene following X-ray exposure that causes the gene to be overexpressed in a tissue-specific manner 
D) X-chromosome deletion that deleted the w+ gene in some cells following X-ray exposure 
E) a mutation in a somatic chromosome that causes the w+ gene to be translocated to the X-chromosomes following X-ray exposure

Question 17

The DNA-protein complex that comprises eukaryotic chromosomes is called ________.

Accepted Answer

The answer of The DNA-protein complex that comprises eukaryotic chromosomes...

Question 18

A cell can form 10 nm chromatin fibers, but not 30 nm fibers. Which molecule has likely been removed or mutated in this cell?

Accepted Answer

A) H1 
B) H2A 
C) H3 
D) topoisomerase 
E) SMC proteins 
A) H1 
B) H2A 
C) H3 
D) topoisomerase 
E) SMC proteins

Question 19

The total amount of hereditary information in an entire set of chromosomes is collectively referred to as an organism's ________.

Accepted Answer

The answer of The total amount of hereditary information in...

Question 20

Which proteins would you target if you wanted to disrupt the chromosome superstructure for chromatin condensation that ultimately produces the characteristic shape of the metaphase chromosome?

Accepted Answer

The answer of Which proteins would you target if you...

Exam 11: Chromosome Structure

What is the purpose of DNA supercoiling?

How might a thermophilic bacterium use chromosome structure to protect against heat-induced DNA degradation?

If heterochromatic spreading encompasses the new location of the w+ gene, what phenotype will the cells have?

What molecular interaction allows histones to interact with DNA?

A bacterium inherits a mutation that renders its topoisomerase enzyme nonfunctional. What phenotype would you expect to see in this bacterium?

Active transcription occurs in regions of chromatin loops that are located __________.

Nucleosomes are comprised of how many molecules of histones?

What is the diameter of a nucleosome?

You are trying to prepare a DNA karyotype, but this time you forgot to add trypsin to your chromosome preparation. What effect would you expect to see?

If you want to prevent chromatin loops from being anchored to the chromosome scaffold, which regions of the DNA would you target?

Under normal cellular conditions, what is the diameter of the chromatin as it forms the solenoid structure?

Quinolones are a group of broad-spectrum antibiotics that specifically target topoisomerase. Explain how this contributes to cell death in bacteria. Would you expect these drugs to kill hyperthermophilic prokaryotes too? Why or why not?

Karyotypes are a method for displaying chromosomes by grouping them into homologous pairs based on what two distinguishing factors?

Archaea have histone proteins that are homologous to the histone proteins found in eukaryotes. Thus far, available evidence indicates that archaeal histone proteins play a role in which function?

The flies with variegated eye color had what abnormal chromosome structure?

The DNA-protein complex that comprises eukaryotic chromosomes is called ________.

A cell can form 10 nm chromatin fibers, but not 30 nm fibers. Which molecule has likely been removed or mutated in this cell?

The total amount of hereditary information in an entire set of chromosomes is collectively referred to as an organism's ________.

Which proteins would you target if you wanted to disrupt the chromosome superstructure for chromatin condensation that ultimately produces the characteristic shape of the metaphase chromosome?

The Molecular Basis of Heredity, Variation, and Evolution

Transmission Genetics

Cell Division and Chromosome Heredity

Gene Interaction

Genetic Linkage and Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Dna Structure and Replication

Molecular Biology and Transcription and Rna Processing

The Molecular Biology of Translation

The Integration of Genetic Approaches: Understanding Sickle Cell Disease

Gene Mutation, Dna Repair, and Homologous Recombination

Chromosome Aberrations and Transposition

Regulation of Gene Expression in Bacteria and Bacteriophages

Regulation of Gene Expression in Eukaryotes

Forward Genetics and Recombinant Dna Technology

Applications of Recombinant Dna Technology and Reverse Genetics

Genomics: Genetics From a Whole-Genome Perspective

Cytoplasmic Inheritance and the Evolution of Organelle Genomes

Developmental Genetics

Genetic Analysis of Quantitative Traits

Population Genetics and Evolution

Filters

If heterochromatic spreading encompasses the new location of the w⁺ gene, what phenotype will the cells have?