Question 1

What kind of supercoils are formed around nucleosomes?

Accepted Answer

A)  positive plectonemic supercoils 
B)  negative plectonemic supercoils 
C)  positive solenoidal supercoils 
D)  negative solenoidal supercoils 
E)  a mixture of solenoidal and plectonemic supercoils 
A)  positive plectonemic supercoils 
B)  negative plectonemic supercoils 
C)  positive solenoidal supercoils 
D)  negative solenoidal supercoils 
E)  a mixture of solenoidal and plectonemic supercoils

Question 2

Which protein(s) is/are NOT associated with bacterial DNA compaction?

Accepted Answer

A) SMC 
B) HU 
C) Type I topoisomerases 
D) Type II topoisomerases 
E) condensin 
A) SMC 
B) HU 
C) Type I topoisomerases 
D) Type II topoisomerases 
E) condensin

Question 3

Which factor contributes to the structure of nucleosomes?

Accepted Answer

A)  plectonemic supercoiled DNA 
B)  relaxed closed-circular DNA 
C)  solenoidal supercoiled DNA 
D)  spacer DNA 
E)  Z (left-handed) DNA 
A)  plectonemic supercoiled DNA 
B)  relaxed closed-circular DNA 
C)  solenoidal supercoiled DNA 
D)  spacer DNA 
E)  Z (left-handed) DNA

Question 4

Which statement is FALSE regarding DNA-binding proteins?

Accepted Answer

A)  DNA-binding proteins always contain zinc finger domains. 
B)  DNA-binding proteins are important in DNA compaction. 
C)  DNA-binding proteins typically interact with DNA via electrostatic interactions. 
D)  DNA binding protein binding to DNA is influenced by the sequence of the nucleic acid. 
E)  DNA-binding proteins often contain Arg and Lys residues. 
A)  DNA-binding proteins always contain zinc finger domains. 
B)  DNA-binding proteins are important in DNA compaction. 
C)  DNA-binding proteins typically interact with DNA via electrostatic interactions. 
D)  DNA binding protein binding to DNA is influenced by the sequence of the nucleic acid. 
E)  DNA-binding proteins often contain Arg and Lys residues.

Question 5

Which statement is FALSE for euchromatin?

Accepted Answer

A)  Euchromatin is a form of chromatin. 
B)  Euchromatin has less H1 associated with it than heterochromatin. 
C)  Euchromatin is being more actively transcribed than heterochromatin. 
D)  Euchromatin is more densely packed than heterochromatin. 
E)  None of these statements is false. 
A)  Euchromatin is a form of chromatin. 
B)  Euchromatin has less H1 associated with it than heterochromatin. 
C)  Euchromatin is being more actively transcribed than heterochromatin. 
D)  Euchromatin is more densely packed than heterochromatin. 
E)  None of these statements is false.

Question 6

Which statement is FALSE regarding the formation of nucleosomes?

Accepted Answer

A)  Histone core proteins occur as pairs in the nucleosome. 
B)  The coiling of DNA around the nucleosome is plectonemic. 
C)  The coiling of DNA around the nucleosome is left-handed. 
D)  Electrostatic interactions between histones and DNA are critical in nucleosome formation. 
E)  The sequence affects the ability of DNA to adopt the curvature in a nucleosome. 
A)  Histone core proteins occur as pairs in the nucleosome. 
B)  The coiling of DNA around the nucleosome is plectonemic. 
C)  The coiling of DNA around the nucleosome is left-handed. 
D)  Electrostatic interactions between histones and DNA are critical in nucleosome formation. 
E)  The sequence affects the ability of DNA to adopt the curvature in a nucleosome.

Question 7

Unwinding a portion of the duplex to carry out transcription on a plasmid will:

Accepted Answer

A)  decrease the overall linking number. 
B)  decrease the overall twist. 
C)  make the writhe more negative. 
D)  increase the overall twist. 
E)  increase the overall linking number. 
A)  decrease the overall linking number. 
B)  decrease the overall twist. 
C)  make the writhe more negative. 
D)  increase the overall twist. 
E)  increase the overall linking number.

Question 8

Bacterial chromosomes:

Accepted Answer

A)  are highly compacted into structures called nucleoids. 
B)  are seen in electron microscopy as "beads on a string." 
C)  are surrounded by a nuclear membrane. 
D)  contain large numbers of nucleosomes. 
E)  when fully extended are as long as the bacterial cell. 
A)  are highly compacted into structures called nucleoids. 
B)  are seen in electron microscopy as "beads on a string." 
C)  are surrounded by a nuclear membrane. 
D)  contain large numbers of nucleosomes. 
E)  when fully extended are as long as the bacterial cell.

Question 9

Which statement is FALSE regarding histones?

Accepted Answer

A)  Overall, histones are positively charged proteins. 
B)  Lys and Arg residues are abundant in histones relative to other proteins. 
C)  Histone H1 is found in the nucleosome core. 
D)  The nucleosome core contains eight histone proteins. 
E)  None of these statements is false. 
A)  Overall, histones are positively charged proteins. 
B)  Lys and Arg residues are abundant in histones relative to other proteins. 
C)  Histone H1 is found in the nucleosome core. 
D)  The nucleosome core contains eight histone proteins. 
E)  None of these statements is false.

Question 10

What is the twist on a piece of relaxed Z-DNA that is 9,600 base pairs long?

Accepted Answer

A)  -960 
B)  -800 
C)  800 
D)  914 
E)  960 
A)  -960 
B)  -800 
C)  800 
D)  914 
E)  960

Question 11

Which protein binds to the linker DNA between nucleosomes?

Accepted Answer

A)  histone H1 
B)  histone H2A 
C)  histone H2B 
D)  histone H3 
E)  histone H4 
A)  histone H1 
B)  histone H2A 
C)  histone H2B 
D)  histone H3 
E)  histone H4

Question 12

Histones are _____ that are usually associated with _____.

Accepted Answer

A)  acidic proteins; DNA 
B)  acidic proteins; RNA 
C)  basic proteins; DNA 
D)  basic proteins; RNA 
E)  coenzymes derived from histidine; enzymes 
A)  acidic proteins; DNA 
B)  acidic proteins; RNA 
C)  basic proteins; DNA 
D)  basic proteins; RNA 
E)  coenzymes derived from histidine; enzymes

Question 13

Briefly describe the changes in eukaryotic chromosome structure during the cell cycle.

Accepted Answer

During the cell cycle, eukaryotic chromo

Question 14

When studying nucleosomes in vitro, researchers will often add the enzyme trypsin to degrade the nucleosomes. Why is trypsin a particularly useful choice for this role?

Accepted Answer

Trypsin is a particularly useful choice

Question 15

Topoisomerases can:

Accepted Answer

A)  change the linking number (Lk) of a DNA molecule. 
B)  change the number of base pairs in a DNA molecule. 
C)  change the number of nucleotides in a DNA molecule. 
D)  convert D isomers of nucleotides to L isomers. 
E)  interconvert DNA and RNA. 
A)  change the linking number (Lk) of a DNA molecule. 
B)  change the number of base pairs in a DNA molecule. 
C)  change the number of nucleotides in a DNA molecule. 
D)  convert D isomers of nucleotides to L isomers. 
E)  interconvert DNA and RNA.

Question 16

Nucleosome formation condenses DNA by approximately sevenfold and 30-nm fiber formation condenses DNA by a further 100-fold. How long will a 450,000 bp segment of linear DNA be after compaction to a 30-nm fiber?

Accepted Answer

A)  ~2 nm 
B)  ~20 nm 
C)  ~200 nm 
D)  ~2,000 nm 
E)  ~20,000 nm 
A)  ~2 nm 
B)  ~20 nm 
C)  ~200 nm 
D)  ~2,000 nm 
E)  ~20,000 nm

Question 17

Explain how inhibitors of topoisomerase would inhibit the growth of tumors. Would these drugs be expected to inhibit the growth of normal cells as well?

Accepted Answer

Topoisomerases are enzymes that are esse

Question 18

Describe the structure and function of a typical bacterial plasmid.

Accepted Answer

A typical bacterial plasmid is a small,

Question 19

With which protein(s) is a condensed eukaryotic chromosome NOT known to be associated?

Accepted Answer

A)  core histones H2A, H2B, H3, and H4 
B)  histone H1 
C)  SMC proteins 
D)  topoisomerase I 
E)  topoisomerase II 
A)  core histones H2A, H2B, H3, and H4 
B)  histone H1 
C)  SMC proteins 
D)  topoisomerase I 
E)  topoisomerase II

Question 20

The overall compaction of a eukaryotic chromosome is greater than ____-fold. The first level is nucleosome formation, which compacts about ____-fold. Next is the 30 nm fiber, which compacts about ____-fold overall. Higher order folding involves association of the DNA with a nuclear _____, which contains large amounts of ____ and ____.

Accepted Answer

The overall compaction of a eukaryotic c

Exam 24: Genes and Chromosomes

What kind of supercoils are formed around nucleosomes?

Which protein(s) is/are NOT associated with bacterial DNA compaction?

Which factor contributes to the structure of nucleosomes?

Which statement is FALSE regarding DNA-binding proteins?

Which statement is FALSE for euchromatin?

Which statement is FALSE regarding the formation of nucleosomes?

Unwinding a portion of the duplex to carry out transcription on a plasmid will:

Bacterial chromosomes:

Which statement is FALSE regarding histones?

What is the twist on a piece of relaxed Z-DNA that is 9,600 base pairs long?

Which protein binds to the linker DNA between nucleosomes?

Histones are _____ that are usually associated with _____.

Briefly describe the changes in eukaryotic chromosome structure during the cell cycle.

When studying nucleosomes in vitro, researchers will often add the enzyme trypsin to degrade the nucleosomes. Why is trypsin a particularly useful choice for this role?

Topoisomerases can:

Nucleosome formation condenses DNA by approximately sevenfold and 30-nm fiber formation condenses DNA by a further 100-fold. How long will a 450,000 bp segment of linear DNA be after compaction to a 30-nm fiber?

Explain how inhibitors of topoisomerase would inhibit the growth of tumors. Would these drugs be expected to inhibit the growth of normal cells as well?

Describe the structure and function of a typical bacterial plasmid.

With which protein(s) is a condensed eukaryotic chromosome NOT known to be associated?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Histones are _ that are usually associated with _.