Chapter 11 Flashcards
- Which of the following is not true of negatively supercoiled DNA?
a. Eases the separation of nucleotide strands during replication and transcription.
b. Allows DNA to be packed into small spaces.
c. Has less than 10 bp per turn of its helix.
d. Is more negatively charged due to additional phosphates per turn of the helix.
e. Is found in most cells.
c
How many complete rotations would most likely correspond to a positively supercoiled DNA molecule that is 100 bp in length?
a. 0
b. 5
c. 10
d. 15
e. 100
d
How many complete rotations would most likely correspond to a negatively supercoiled DNA molecule that is 100 bp in length?
a. 0
b. 5
c. 10
d. 15
e. 100
b
How many complete rotations would most likely correspond to a relaxed DNA molecule that is 100 bp in length?
a. 0
b. 5
c. 10
d. 15
e. 100
c
How many base pairs per turn of the helix would most likely correspond to a relaxed DNA molecule?
a. 0
b. 5
c. 10
d. 15
e. 100
c
How many base pairs per turn of the helix would most likely correspond to a positively supercoiled DNA molecule?
a. 0
b. 5
c. 10
d. 15
e. 100
b
How many base pairs per turn of the helix would most likely correspond to a negatively supercoiled DNA molecule?
a. 0
b. 5
c. 10
d. 15
e. 100
d
Which of the following is not true of bacterial DNA?
a. Most bacterial genomes consist of a single circular DNA molecule.
b. Bacterial DNA is not attached to any proteins that help to compact it.
c. Bacterial DNA is confined to a region in the cell called the nucleoid.
d. Many bacteria contain additional DNA in the form of small circular molecules called plasmids.
e. About 3 to 4 million base pairs of DNA are found in a typical bacterial genome.
b
You are studying a small eukaryotic gene of about 2000 bp in length. Estimate how many copies of histone H4 you would find along this region of the chromosome.
a. 10
b. 20
c. 40
d. 80
e. 100
b
You are studying a small eukaryotic gene of about 2000 bp in length. Estimate how many copies of histone H1 you would find along this region of the chromosome.
a. 10
b. 20
c. 40
d. 80
e. 100
a
The human Y chromosome is about 50 million base pairs long. About how many nucleosomes would you expect to find associated with this chromosome?
a. 2,500
b. 50,000
c. 250,000
d. 1,000,000
e. 50,000,000
a
Which of the following amino acids has a positive charge that helps to hold the DNA in contact with the histones?
a. Alanine
b. Arginine
c. Leucine
d. Valine
e. Serine
b
Which of the following is not true of heterochromatin?
a. Remains in a highly condensed state throughout the cell cycle
b. Makes up most chromosomal material and is where most transcription occurs
c. Exists at the centromeres and telomeres
d. Occurs along one entire X chromosome in female mammals when this X becomes inactivated
e. Is characterized by the absence of crossing over and replication late in the S phase
b
How does histone acetylation affect chromatin?
a. It loosens the chromatin and allows increased transcription.
b. It allows DNA to become resistant to damage.
c. It helps the histones have a greater affinity for DNA.
d. It inhibits DNA replication by making it more difficult to separate the DNA strands.
e. It causes the chromatin to become more condensed in preparation for metaphase.
a
Which of the following is an example of an epigenetic change in eukaryotes?
a. A loss of an AT base pair from a gene
b. The addition of methyl groups to cytosines in the promoter region of a gene
c. The substitution of an AT base pair by a GC base pair in a gene as a result of a mistake during DNA replication
d. A deletion that simultaneously removes two genes from the genome
e. None of the above represent epigenetic changes.
b
The agouti locus helps determine coat color in mice, and this phenotype can vary from light to dark between genetically identical individuals. You have discovered a drug that reduces the variation in the agouti phenotype. What is a likely explanation for this drug’s mechanism of action.
a. Inhibits DNA polymerases
b. Inhibits DNA methyl transferases
c. Activates shelterin proteins
d. Activates mitochondrial transcription
e. Causes DNA damage
b
Which of the following has repetitive DNA and heterochromatin?
a. Telomere
b. Centromere
c. Mitochondria
d. Chloroplast
e. a and b
e
Where would you expect to find the variant histone CenH3?
a. telomere
b. euchromatin
c. centromere
d. mitochondria
e. chloroplast
c
Telomeres exist to help with the _________ of the ends of eukaryotic chromosomes.
a. transcription
b. replication
c. metabolism
d. destabilization
e. translation
b
A normal chromosome in a higher eukaryotic species would be expected to contain all of the following except:
a. One centromere
b. One telomere
c. Two copies of histone 2A per nucleosome
d. Satellite DNA
e. Tandem repeat sequences
b
An Alu sequence is an example of which type of DNA sequence in eukaryotes?
a. Moderately repetitive DNA
b. Highly repetitive DNA
c. Short interspersed elements
d. Long interspersed elements
e. Unique-sequence DNA
c
A telomere is an example of which type of DNA sequence in eukaryotes?’
a. moderately repetitive DNA
b. Highly repetitive DNA
c. Short interspersed elements
d. Long interspersed elements
e. Unique-sequence DNA
b
A gene-encoding sequence is an example of which type of DNA sequence in eukaryotes?
a. Moderately repetitive DNA
b. Highly repetitive DNA
c. Short interspersed elements
d. Long interspersed elements
e. Unique-sequence DNA
e
A tRNA gene is an example of which type of DNA sequence in eukaryotes?
a. Moderately repetitive DNA
b. Highly repetitive DNA
c. Short interspersed elements
d. Long interspersed elements
e. Unique-sequence DNA
a
