Question 1

Which histone is replaced in nucleosomes found in the vicinity of centromeres?

Accepted Answer

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

Question 2

What are introns?

Accepted Answer

Introns are non-coding sections of an RN

Question 3

Approximately what fraction of the human genome is tranaposable elements?

Accepted Answer

A)  1.5% 
B)  5% 
C)  10% 
D)  45% 
E)  80% 
A)  1.5% 
B)  5% 
C)  10% 
D)  45% 
E)  80%

Question 4

The formation of cruciforms in relaxed, circular DNA will be associated with what other effect?

Accepted Answer

A)  a change in linking number 
B)  a change in superhelical density 
C)  the formation of negative supercoils 
D)  All of these effects would occur. 
E)  None of these effects would occur. 
A)  a change in linking number 
B)  a change in superhelical density 
C)  the formation of negative supercoils 
D)  All of these effects would occur. 
E)  None of these effects would occur.

Question 5

Which statement is FALSE concerning human mitochondrial DNA (mtDNA)?

Accepted Answer

A)  Human mtDNA is circular. 
B)  Human mtDNA is smaller than the E. coli genome. 
C)  Human mtDNA encodes the majority of mitochondrial protein genes. 
D)  Human mtDNA is typically found as multiple copies in mitochondria. 
E)  Human mtDNA encodes both polypeptide and tRNA genes. 
A)  Human mtDNA is circular. 
B)  Human mtDNA is smaller than the E. coli genome. 
C)  Human mtDNA encodes the majority of mitochondrial protein genes. 
D)  Human mtDNA is typically found as multiple copies in mitochondria. 
E)  Human mtDNA encodes both polypeptide and tRNA genes.

Question 6

Under what conditions will the linking number for a plasmid change?

Accepted Answer

A)  cruciform formation 
B)  addition of an intercalating agent 
C)  denaturation 
D)  addition of histones 
E)  None of these conditions will change the linking number. 
A)  cruciform formation 
B)  addition of an intercalating agent 
C)  denaturation 
D)  addition of histones 
E)  None of these conditions will change the linking number.

Question 7

Define, in the context of DNA structure, "topological bonds."

Accepted Answer

In the context of DNA structure, "topolo

Question 8

What kind of posttranslational modifications occur in histones?

Accepted Answer

A)  methylation only 
B)  acetylation only 
C)  phosphorylation only 
D)  methylation and acetylation 
E)  methylation, acetylation and phosphorylation 
A)  methylation only 
B)  acetylation only 
C)  phosphorylation only 
D)  methylation and acetylation 
E)  methylation, acetylation and phosphorylation

Question 9

Define, in the context of DNA structure, "topoisomers."

Accepted Answer

Topoisomers are different molecular form

Question 10

Describe two functions of DNA supercoiling.

Accepted Answer

DNA supercoiling refers to the over- or

Question 11

Which statement is FALSE regarding supercoils in nucleic acids?

Accepted Answer

A)  Supercoils allow DNA to become more compact. 
B)  Most naturally occuring DNA has a linking number that is greater than the twist. 
C)  Supercoiling requires DNA that is either circular or has constrained ends. 
D)  Positive solenoidal supercoils have the opposite handedness to positive plectonemic supercoils. 
E)  The twist for Z-DNA will have a negative value. 
A)  Supercoils allow DNA to become more compact. 
B)  Most naturally occuring DNA has a linking number that is greater than the twist. 
C)  Supercoiling requires DNA that is either circular or has constrained ends. 
D)  Positive solenoidal supercoils have the opposite handedness to positive plectonemic supercoils. 
E)  The twist for Z-DNA will have a negative value.

Question 12

Starting with a 5,000 bp plasmid containing one positive supercoil, after one round of E. coli DNA gyrase action, what would be the supercoiling state of the plasmid?

Accepted Answer

A)  three positive supercoils 
B)  two positive supercoils 
C)  no supercoils 
D)  one negative supercoil 
E)  two negative supercoils 
A)  three positive supercoils 
B)  two positive supercoils 
C)  no supercoils 
D)  one negative supercoil 
E)  two negative supercoils

Question 13

The MOST precise modern definition of a gene is a segment of genetic material that:

Accepted Answer

A)  codes for one polypeptide. 
B)  codes for one polypeptide or RNA product. 
C)  determines one phenotype. 
D)  determines one trait. 
E)  that codes for one protein. 
A)  codes for one polypeptide. 
B)  codes for one polypeptide or RNA product. 
C)  determines one phenotype. 
D)  determines one trait. 
E)  that codes for one protein.

Question 14

Which statement about nucleic acids is FALSE?

Accepted Answer

A)  Mitochondria and chloroplasts contain DNA. 
B)  Plasmids are genes that encode plasma proteins in mammals. 
C)  The chromosome of E. coli is a closed-circular, double-helical DNA. 
D)  The DNA of viruses is usually much longer than the viral particle itself. 
E)  The genome of many plant viruses is RNA. 
A)  Mitochondria and chloroplasts contain DNA. 
B)  Plasmids are genes that encode plasma proteins in mammals. 
C)  The chromosome of E. coli is a closed-circular, double-helical DNA. 
D)  The DNA of viruses is usually much longer than the viral particle itself. 
E)  The genome of many plant viruses is RNA.

Question 15

Explain the difference between plectonemic and solenoidal supercoiling of DNA; use diagrams to help in your explanation.

Accepted Answer

Plectonemic and solenoidal supercoiling

Question 16

Acetylation of lysine residues in histones has what effect?

Accepted Answer

A)  It increases the positive charge on the protein and increases compaction. 
B)  It increases the positive charge on the protein and decreases compaction. 
C)  It decreases the positive charge on the protein and increases compaction. 
D)  It decreases the positive charge on the protein and decreases compaction. 
E)  None of the answers is correct. 
A)  It increases the positive charge on the protein and increases compaction. 
B)  It increases the positive charge on the protein and decreases compaction. 
C)  It decreases the positive charge on the protein and increases compaction. 
D)  It decreases the positive charge on the protein and decreases compaction. 
E)  None of the answers is correct.

Question 17

Define topoisomerase, and explain the difference between type I and type II topoisomerases.

Accepted Answer

Topoisomerases are enzymes that are resp

Question 18

Topoisomerases:

Accepted Answer

A)  can change the linking number in increments of 1 or 2. 
B)  can act on single-stranded DNA circles. 
C)  change the degree of supercoiling of a DNA molecule but not its linking number of DNA. 
D)  occur in bacteria, but not in eukaryotes. 
E)  always require energy from ATP. 
A)  can change the linking number in increments of 1 or 2. 
B)  can act on single-stranded DNA circles. 
C)  change the degree of supercoiling of a DNA molecule but not its linking number of DNA. 
D)  occur in bacteria, but not in eukaryotes. 
E)  always require energy from ATP.

Question 19

In which cell-cycle step does condensin become associated with chromatids?

Accepted Answer

A)  G1/S 
B)  S/G2 
C)  during prophase 
D)  during anaphase 
E)  during telophase 
A)  G1/S 
B)  S/G2 
C)  during prophase 
D)  during anaphase 
E)  during telophase

Question 20

Partially denaturing a stretch of duplex in closed, circular plasmid DNA will have what effect?

Accepted Answer

A)  It will decrease linking number and increase writhe. 
B)  It will decrease twist and linking number. 
C)  It will increase writhe and decrease twist. 
D)  It will decrease both writhe and twist. 
E)  It will increase linking number and reduce writhe. 
A)  It will decrease linking number and increase writhe. 
B)  It will decrease twist and linking number. 
C)  It will increase writhe and decrease twist. 
D)  It will decrease both writhe and twist. 
E)  It will increase linking number and reduce writhe.

Exam 24: Genes and Chromosomes

Which histone is replaced in nucleosomes found in the vicinity of centromeres?

What are introns?

Approximately what fraction of the human genome is tranaposable elements?

The formation of cruciforms in relaxed, circular DNA will be associated with what other effect?

Which statement is FALSE concerning human mitochondrial DNA (mtDNA)?

Under what conditions will the linking number for a plasmid change?

Define, in the context of DNA structure, "topological bonds."

What kind of posttranslational modifications occur in histones?

Define, in the context of DNA structure, "topoisomers."

Describe two functions of DNA supercoiling.

Which statement is FALSE regarding supercoils in nucleic acids?

Starting with a 5,000 bp plasmid containing one positive supercoil, after one round of E. coli DNA gyrase action, what would be the supercoiling state of the plasmid?

The MOST precise modern definition of a gene is a segment of genetic material that:

Which statement about nucleic acids is FALSE?

Explain the difference between plectonemic and solenoidal supercoiling of DNA; use diagrams to help in your explanation.

Acetylation of lysine residues in histones has what effect?

Define topoisomerase, and explain the difference between type I and type II topoisomerases.

Topoisomerases:

In which cell-cycle step does condensin become associated with chromatids?

Partially denaturing a stretch of duplex in closed, circular plasmid DNA will have what effect?

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