Exam 2 Quizzes Flashcards
The core octamer of a nucleosome is composed of
two tetramers of histones H3 and H4
a tetramer of histones H3 and H4, and two dimers of histones H2A and H2B
the linker histone H1
one each of 8 different types of histones
a tetramer of histones H3 and H4, and two dimers of histones H2A and H2B
The site of many post-translational modification of the histone proteins is the
extended histone-fold domain at the C-terminal end
conserved wing helix folds
charged tails at the N-terminal end
charged tails at the C-terminal end
charged tails at the N-terminal end
Brief digestion of eukaryotic chromatin with micrococcal nuclease gives a visible ladder of bands on an agarose gel separated from each other by multiples of ~180 bp. The fragment size represents
multiples of single nucleosomal repeat lengths of DNA
DNA that was wrapped around the core histone octamer
the different histone proteins
linker DNA
multiples of single nucleosomal repeat lengths of DNA
The location of the centromere within a chromosome is determined by
the presence of an evolutionarily conserved centromere-determining sequence.
the presence of the histone variant CENP-A.
the presence of linker histone.
the point of equidistance between the two chromosome ends
the presence of the histone variant CENP-A.
Heterochromatin is
decondensed, transcriptionally silent chromatin.
condensed, transcriptionally silent chromatin.
decondensed, transcriptionally active chromatin.
condensed, transcriptionally active chromatin.
condensed, transcriptionally silent chromatin.
Which of the following occupies the largest portion of the human genome?
introns
intergenic DNA
gene regulatory sequences
protein-coding sequences
intergenic DNA
Condensation of chromatin requires ATP-hydrolyzing enzymes and __________to loop DNA and achieve a 10,000 fold packing ratio.
the cohesin complex
the condensin complex
the kinetochore complex
the Ki-67 proteins
the condensin complex
What statement is not true about plasmid DNA?
Most plasmids are small, double-stranded circles.
Plasmid DNA is only found in bacteria
Plasmid DNA is extrachromosomal
Plasmid DNA is self-replicating
Plasmid DNA is only found in bacteria
Which of the following is true of bacteriophage DNA packaging?
Bacteriophages take their host cell’s histone proteins to package their DNA
Bacteriophages must pack their genome into a nucleus
Bacteriophages usually have a lot of proteins associated with their DNA, helping to package it
Bacteriophages must pack their genome into a capsid
Bacteriophages must pack their genome into a capsid
Histone proteins are the main architectural proteins found in bacteria.
True False
False
Mitochondria contain DNA that encodes proteins important for oxidative phosphorylation.
True False
True
Which of the following statements is correct?
There are five types of DNA polymerase in mammalian cells.
There is only one type of DNA polymerase in bacterial cells.
DNA polymerase requires a primer to get started.
DNA polymerase catalyzes the formation of a phosphodiester bond between the first 3′hydroxyl group of the new dNTP and the 5′-phosphate of the last nucleotide in the newly synthesized strand.
DNA polymerase can start synthesis de novo.
DNA polymerase requires a primer to get started.
Which of the following is NOT TRUE with regards to DNA replication?
DNA replication in bacteria is normally bidirectional
DNA replication on the lagging strand is continuous
DNA replication is semiconservative
DNA replication initiation begins at a negatively supercoiled origin of replication
The origin of replication is rich in A and T nucleotides.
DNA replication on the lagging strand is continuous
Which of the following is an enzyme that would be found in Escherichia coli but not in humans?
RFC
DNA pol alpha
DNA pol I
Mcm2-7
PCNA
DNA pol I
What protein or protein complex binds to the origin of replication in E. coli cells to initiate DNA replication?
DnaA
Topoisomerase II
Mcm2-7
Helicase
ORC
DnaA
When does DNA replication occur in a eukaryotic cell?
M phase
G2 phase
S phase
G1 phase
S phase
Which statement is NOT correct?
Mammalian origins of replication do not have a consensus sequence
An origin of replication is a site on chromosomal DNA where a bidirectional pair of replication forks initiates.
Eukaryotic chromosomal DNA typically has only one origin of replication
Eukaryotic chromosomal DNA replication occurs after replication licensing
Eukaryotic chromosomal DNA typically has only one origin of replication
Which enzyme is responsible for sealing the DNA backbone following primer removal?
Helicase
RNA polymerase
DNA ligase
DNA gyrase
Restriction endonuclease
DNA ligase
Which enzyme causes a double-strand DNA break while functioning?
RPA
Topoisomerase II
Klenow fragment
DNA helicase
Clamp loader
Topoisomerase I
Topoisomerase II
Select all of the following that describe DNA transactions during replication.
It is bidirectional with 2 replication forks
It is conservative
The main enzyme for replication is DNA polymerase
It does not have a specific beginning
It is semidiscontinuous
- It is bidirectional with 2 replication forks
- The main enzyme for replication is DNA polymerase
- It is semidiscontinuous
An induced mutation occurs
as a result of DNA replication errors
as a result of natural processes in cells
spontaneously
as a result of interaction of DNA with an outside agent
as a result of interaction of DNA with an outside agent
The most frequent UV light-induced DNA damage is
induction of 5-bromouracil
double-strand breaks
forming a thymine dimer
oxidation of guanine to 8-oxoguanine
forming a thymine dimer
Which of the following is an intercalating agent?
8-Oxoguanine
Nitrosamines
5-bromouracil
Ethidium bromide
Ethidium bromide
Removal of DNA-protein cross-links will most likely occur using which of the following enzymes?
DNA photolyase
SPRTN protease
methyltransferase
DNA polymerase IV
SPRTN protease
Which repair pathway would probably be involved in specifically recognizing and removing uracil (and other modified bases) from DNA?
homologous recombination
nucleotide excision repair
base excision repair
non-homologous end joining
base excision repair
The XP proteins are important for which type of repair?
non-homologous end-joining
nucleotide excision
direct repair
base excision
nucleotide excision
DNA repair mechanisms exhibit a recurrent theme. Which of the following describes this theme accurately?
A nuclease cuts out the damage, a polymerase adds in the correct nucleotides, a ligase fills in the nick in the backbone.
A polymerase removes DNA damage, a nuclease adds in the correct nucleotides, and a ligase seals double stranded DNA breaks
A ribosome recognizes the damage, a RNA polymerase translates the DNA sequence, and a DNA polymerase connects double stranded DNA
A methyltransferase recognizes DNA damage, a glycosylase cuts the damage out, and a photolyase adds in the correct nucleotides
A nuclease cuts out the damage, a polymerase adds in the correct nucleotides, a ligase fills in the nick in the backbone.
Which type of repair uses DNA glycosylases?
direct repair
non-homologous end-joining
nucleotide excision
base excision
base excision
The DNA repair system that removes replication errors and requires Mut proteins is
Potoreactivation
Mismatch repair
Translesion DNA synthesis
Nucleotide excision repair
Mismatch repair
Xeroderma pigmentosum may be caused by mutation in the gene that encodes DNA polymerase eta (η).
True False
True
DNA polymerase eta (η) repairs DNA damage.
True False
False
