Question 1

It is correct to say that DNA supercoiling cannot:

Accepted Answer

A) be induced by strand separation. 
B) be induced by underwinding of the double helix. 
C) form if there is Z-DNA structure present. 
D) occur if a closed circular double-stranded DNA molecule has a nick. 
E) result in compaction of the DNA structure. 
A) be induced by strand separation. 
B) be induced by underwinding of the double helix. 
C) form if there is Z-DNA structure present. 
D) occur if a closed circular double-stranded DNA molecule has a nick. 
E) result in compaction of the DNA structure.

Question 2

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

Accepted Answer

Starting with prophase,the DNA undergoes

Question 3

Which of the following does not contribute to the octameric histone core?

Accepted Answer

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

Question 4

A condensed eukaryotic chromosome is known to be associated with all of the following proteins,except for:

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 5

Bacterial plasmids:

Accepted Answer

A) are always covalently joined to the bacterial chromosome. 
B) are composed of RNA. 
C) are never circular. 
D) cannot replicate when cells divide. 
E) often encode proteins not normally essential to the bacterium's survival. 
A) are always covalently joined to the bacterial chromosome. 
B) are composed of RNA. 
C) are never circular. 
D) cannot replicate when cells divide. 
E) often encode proteins not normally essential to the bacterium's survival.

Question 6

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 7

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

Dividing cells must replicate their DNA;

Question 8

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

Accepted Answer

Topoisomers are different form

Question 9

Functional DNA is not found in:

Accepted Answer

A) bacterial nucleoids. 
B) chloroplasts. 
C) lysosomes. 
D) mitochondria. 
E) nuclei. 
A) bacterial nucleoids. 
B) chloroplasts. 
C) lysosomes. 
D) mitochondria. 
E) nuclei.

Question 10

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 11

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 12

The SMC proteins (for structural maintenance of chromosomes)include cohesins and condensins,and are known to have all of the following properties except:

Accepted Answer

A) a complete ATP binding site. 
B) a hinge region. 
C) topoisomerase activity to produce positive supercoils. 
D) the ability to condense DNA. 
E) two coiled-coil domains. 
A) a complete ATP binding site. 
B) a hinge region. 
C) topoisomerase activity to produce positive supercoils. 
D) the ability to condense DNA. 
E) two coiled-coil domains.

Question 13

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

10,000
7
100
scaffol

Question 14

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 15

Plectonemic supercoils in a negatively supercoiled DNA molecule:

Accepted Answer

A) are always left-handed. 
B) are always right-handed. 
C) are balanced by solenoidal supercoils 
D) can be either right- or left-handed. 
E) never occur. 
A) are always left-handed. 
B) are always right-handed. 
C) are balanced by solenoidal supercoils 
D) can be either right- or left-handed. 
E) never occur.

Question 16

Nucleosomes:

Accepted Answer

A) are important features of chromosome organization in eukaryotes and bacteria. 
B) are composed of proteins rich in acidic amino acids,such as Asp and Glu. 
C) are composed of protein and RNA. 
D) bind DNA and alter its supercoiling. 
E) occur in chromatin at irregular intervals along the DNA molecule. 
A) are important features of chromosome organization in eukaryotes and bacteria. 
B) are composed of proteins rich in acidic amino acids,such as Asp and Glu. 
C) are composed of protein and RNA. 
D) bind DNA and alter its supercoiling. 
E) occur in chromatin at irregular intervals along the DNA molecule.

Question 17

For a closed-circular DNA molecule of 10,000 base pairs in the fully relaxed form,the linking number (Lk)is about:

Accepted Answer

A) 10,000. 
B) 950. 
C) 100. 
D) 9)5. 
E) 2) 
A) 10,000. 
B) 950. 
C) 100. 
D) 9)5. 
E) 2)

Question 18

Which of these statements 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 19

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

Accepted Answer

In plectonemic supercoiling,the double h

Question 20

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

Exam 24: Genes and Chromosomes

It is correct to say that DNA supercoiling cannot:

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

Which of the following does not contribute to the octameric histone core?

A condensed eukaryotic chromosome is known to be associated with all of the following proteins,except for:

Bacterial plasmids:

Topoisomerases:

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?

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

Functional DNA is not found in:

Topoisomerases can:

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

The SMC proteins (for structural maintenance of chromosomes)include cohesins and condensins,and are known to have all of the following properties except:

Approximately what fraction of the human genome is tranaposable elements?

Plectonemic supercoils in a negatively supercoiled DNA molecule:

Nucleosomes:

For a closed-circular DNA molecule of 10,000 base pairs in the fully relaxed form,the linking number (Lk)is about:

Which of these statements about nucleic acids is false?

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

Histones are _______ that are usually associated with _________.

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

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

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

Integration and Hormonal Regulation of Mammalian Metabolism

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Histones are _ that are usually associated with ___.