Question 1

Which elements are NOT necessary to make a stable yeast artificial chromosome (YAC)?

Accepted Answer

A)  centromeres 
B)  replication origins 
C)  satellite DNA sequences 
D)  telomeres 
E)  All of these are required to make a stable YAC. 
A)  centromeres 
B)  replication origins 
C)  satellite DNA sequences 
D)  telomeres 
E)  All of these are required to make a stable YAC.

Question 2

Which protein carries out ATP hydrolysis?

Accepted Answer

A)  histone H2A 
B)  histone H1 
C)  E. coli topoisomerase I 
D)  condensin 
E)  E. coli topoisomerase III 
A)  histone H2A 
B)  histone H1 
C)  E. coli topoisomerase I 
D)  condensin 
E)  E. coli topoisomerase III

Question 3

The eukaryotic SMC protein condensin contains which SMC subunits?

Accepted Answer

A)  SMC1 and SMC2 
B)  SMC1 and SMC3 
C)  SMC2 and SMC3 
D)  SMC2 and SMC4 
E)  SMC3 and SMC4 
A)  SMC1 and SMC2 
B)  SMC1 and SMC3 
C)  SMC2 and SMC3 
D)  SMC2 and SMC4 
E)  SMC3 and SMC4

Question 4

Which statement is TRUE for histones?

Accepted Answer

A)  They vary in size from 200 to 400 amino acids in length. 
B)  They form covalent complexes with DNA. 
C)  They form both protein:DNA and protein:protein interactions. 
D)  They contain large amounts of Asp residues. 
E)  DNA wraps around them in a right-handed helical structure. 
A)  They vary in size from 200 to 400 amino acids in length. 
B)  They form covalent complexes with DNA. 
C)  They form both protein:DNA and protein:protein interactions. 
D)  They contain large amounts of Asp residues. 
E)  DNA wraps around them in a right-handed helical structure.

Question 5

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 6

A commonality between type I and type II topoisomerases is that they both:

Accepted Answer

A)  change the linking number in increments of 1 or 2. 
B)  require ATP. 
C)  go through a mechanism using a covalent enzyme-substrate intermediate. 
D)  are inhibited by quinoline antibiotics. 
E)  All of the answers are correct. 
A)  change the linking number in increments of 1 or 2. 
B)  require ATP. 
C)  go through a mechanism using a covalent enzyme-substrate intermediate. 
D)  are inhibited by quinoline antibiotics. 
E)  All of the answers are correct.

Question 7

Introns:

Accepted Answer

A)  are frequently present in prokaryotic genes but are rare in eukaryotic genes. 
B)  are spliced out before transcription. 
C)  are translated but not transcribed. 
D)  can occur many times within a single gene. 
E)  encode unusual amino acids in proteins. 
A)  are frequently present in prokaryotic genes but are rare in eukaryotic genes. 
B)  are spliced out before transcription. 
C)  are translated but not transcribed. 
D)  can occur many times within a single gene. 
E)  encode unusual amino acids in proteins.

Question 8

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 9

The genome of organism A is 4.6 million base pairs long, while that of organism B is 12.1 million base pairs long. Given this information, what can be stated regarding these two organisms?

Accepted Answer

A)  Organism B will contain approximately three times the number of genes as organism A. 
B)  Organism B will contain approximately 7.5 million more base pairs in introns compared with organism A. 
C)  Organism B will contain three times as many chromosomes as organism A. 
D)  All of the statements are valid. 
E)  None of the statements is valid. 
A)  Organism B will contain approximately three times the number of genes as organism A. 
B)  Organism B will contain approximately 7.5 million more base pairs in introns compared with organism A. 
C)  Organism B will contain three times as many chromosomes as organism A. 
D)  All of the statements are valid. 
E)  None of the statements is valid.

Question 10

Define "specific linking difference" ($\sigma$), also called superhelical density.

Accepted Answer

The "specific linking difference," also

Question 11

Which factor distinguishes bacterial topoisomerase III from topoisomerase IB?

Accepted Answer

A)  consumption of ATP 
B)  cleavage of one or two strands 
C)  relaxing or increasing the amount of supercoiling 
D)  the mechanism of action 
E)  amino acid involved in covalent attachment to nucleic acid 
A)  consumption of ATP 
B)  cleavage of one or two strands 
C)  relaxing or increasing the amount of supercoiling 
D)  the mechanism of action 
E)  amino acid involved in covalent attachment to nucleic acid

Question 12

DNA in a closed-circular, double-stranded molecule with no net bending of the DNA axis on itself is:

Accepted Answer

A)  a left-handed helix. 
B)  a mixed right- and left-handed helix. 
C)  relaxed. 
D)  supercoiled. 
E)  underwound. 
A)  a left-handed helix. 
B)  a mixed right- and left-handed helix. 
C)  relaxed. 
D)  supercoiled. 
E)  underwound.

Question 13

SMC proteins facilitate the structural maintenance of chromosomes; describe the roles of the two main classes.

Accepted Answer

The two main classes of SMC proteins are

Question 14

An average base pair in DNA is 650 Da. Histone masses are shown in the table. What is the approximate mass of a nucleosome core in kiloDaltons (kDa)? Histone
Mass (Daltons)
Histone H1
21,130
Histone H2A
13,960
Histone H2B
13,774
Histone H3
15,273
Histone H4
11,236

Accepted Answer

A)  ~55 kDa 
B)  ~75 kDa 
C)  ~170 kDa 
D)  ~205 kDa 
E)  ~230 kDa 
A)  ~55 kDa 
B)  ~75 kDa 
C)  ~170 kDa 
D)  ~205 kDa 
E)  ~230 kDa

Question 15

Which protein is NOT important in the compaction of eukaryotic DNA?

Accepted Answer

A)  histone H1 
B)  cohesins 
C)  condensins 
D)  topoisomerases 
E)  HU proteins 
A)  histone H1 
B)  cohesins 
C)  condensins 
D)  topoisomerases 
E)  HU proteins

Question 16

In which phase of the cell cycle is DNA MOST condensed?

Accepted Answer

A)  G1 phase 
B)  S phase 
C)  G2 phase 
D)  prophase 
E)  metaphase 
A)  G1 phase 
B)  S phase 
C)  G2 phase 
D)  prophase 
E)  metaphase

Question 17

How many nucleosomes would you expect to find in a 1,000 bp piece of linear DNA?

Accepted Answer

A)  zero to one 
B)  two to three 
C)  four to five 
D)  six to seven 
E)  eight to nine 
A)  zero to one 
B)  two to three 
C)  four to five 
D)  six to seven 
E)  eight to nine

Question 18

Which aspect does NOT distinguish bacterial SMC proteins from eukaryotic SMC proteins?

Accepted Answer

A) formation of coiled-coil structures 
B) binding and hydrolysis of ATP 
C) formation of "hinge" domains 
D) formation of "head" domains 
E) formation of homodimers versus heterodimers 
A) formation of coiled-coil structures 
B) binding and hydrolysis of ATP 
C) formation of "hinge" domains 
D) formation of "head" domains 
E) formation of homodimers versus heterodimers

Question 19

The SMC proteins (for structural maintenance of chromosomes) include cohesins and condensins and are NOT known to have:

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.

Exam 24: Genes and Chromosomes

Which elements are NOT necessary to make a stable yeast artificial chromosome (YAC)?

Which protein carries out ATP hydrolysis?

The eukaryotic SMC protein condensin contains which SMC subunits?

Which statement is TRUE for histones?

Plectonemic supercoils in a negatively supercoiled DNA molecule:

A commonality between type I and type II topoisomerases is that they both:

Introns:

Bacterial plasmids:

The genome of organism A is 4.6 million base pairs long, while that of organism B is 12.1 million base pairs long. Given this information, what can be stated regarding these two organisms?

Define "specific linking difference" ( σ\sigmaσ ), also called superhelical density.

Which factor distinguishes bacterial topoisomerase III from topoisomerase IB?

DNA in a closed-circular, double-stranded molecule with no net bending of the DNA axis on itself is:

SMC proteins facilitate the structural maintenance of chromosomes; describe the roles of the two main classes.

An average base pair in DNA is 650 Da. Histone masses are shown in the table. What is the approximate mass of a nucleosome core in kiloDaltons (kDa)? Histone Mass (Daltons) Histone H1 21,130 Histone H2A 13,960 Histone H2B 13,774 Histone H3 15,273 Histone H4 11,236

Which protein is NOT important in the compaction of eukaryotic DNA?

In which phase of the cell cycle is DNA MOST condensed?

How many nucleosomes would you expect to find in a 1,000 bp piece of linear DNA?

Which aspect does NOT distinguish bacterial SMC proteins from eukaryotic SMC proteins?

The SMC proteins (for structural maintenance of chromosomes) include cohesins and condensins and are NOT known to have:

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Filters

Define "specific linking difference" ( $\sigma$ ), also called superhelical density.