Old Quiz and Exam Questions Flashcards
How is the poly-A tail added to eukaryotic mRNA?
Poly-A polymerase adds it
How are rRNAs produced?
The three largest ones are transcribed as a single unit, and then separated by endonucleases
Eukaryotic introns must contain an “A” base that is important for splicing because
the 2’ OH of this adenosine attacks the linkage at the 5’ end of the intron in the first step of the splicing reaction
A 5’ to 5’ phosphate bridge is found in
the 5’ cap of eukaryotic mRNAs
Would you expect to find attenuation in control of gene expression in eukaryotes?
No, because in eukaryotes transcription and translation occur in separate compartments
In eukaryotes, RNA polymerase II is responsible for
transcription of mRNAs
The TATA binding protein is part of which basal transcription factor?
TFIID
Which of the following is a common DNA binding domain?
a) ankyrin repeat
b) beta-sheet
c) leucine rich repeat
d) P-loop
e) zinc finger
zinc finger
What does the HIV reverse transcriptase use as a primer?
a tRNA from the previous host cell carried in the vial capsid
what is the function of the HIV protease?
it cleaves the viral polyproteins into individual proteins
antigen binding to a specific B cell causes it to
proliferate and secrete IgG antibodies
IgG antibodies consist of
two identical heavy chains and two identical light chains
where does VDJ recombination occur?
in the DNA of the immunoglobulin loci in B cell precursors
in V to J recombination in the light chain locus, what happens to the sequence between V and J cassettes?
it is removed as a circular DNA molecule and is degraded
In eukaryotes, how is the first codon for translation determined?
translation starts with the first AUG codon after the 5’ cap
if the sequence of a tRNA is 5’ ACG 3’, which codon will it read?
5’ CGU 3’
Ribosomes create peptide bonds
that join the amino group of an amino acid attached to a tRNA in the “A” site to the carboxyl group of an amino acid joined to a tRNA in the “P” site
termination of translation is determined by
the release factor binding to the stop codon in the A site of the ribosome
A stretch of DNA reads 5’ GCCATT 3’ on the non-template strand. What is the sequence of the RNA transcribed from it?
5’ GCCAUU 3’
what are properties of DNA polymerases and not RNA polymerases?
DNA polymerases need a primer and synthesize both strands of a nucleic acid molecule
in prokayotes, transcription termination is determined by
a protein called rho
UV causes
thymine dimers
what human disease is caused by a defect in DNA repair?
Xeroderma pigmentosum
which definition of a mutation is most accurate
mutations are any changes in an organism’s DNA sequence
a stretch of protein-coding DNA with a sequence of GGCAT is mutated to GGGCAT. this is an example of
a frameshift
Incorrect bases introduced during DNA replication are usually corrected by
mismatch repair
What causes the structure of a DNA double helix to have a major groove and a minor groove?
the angles of the glycosidic bonds
What was the result of the Meselson-Stahl experiment
one band, half-heavy, half-light
In a Sanger DNA sequencing reaction using a capillary sequencing machine, the base at the 3’ end of a newly-synthesized DNA strand is identified by
different fluorescent dyes attached to the dideoxy versions of each base
Banana plants have three copies of each chromosome. This is an example of
triploidy
In a sample of nucleic acid, 23% of the bases are adenine, 25% are cytosine, 26% are guanine and 26% are thymine. the nucleic acid is most likely
a single stranded DNA
What’s a step of the gene editing process?
a Cas9 nuclease cuts a DNA molecule at a position determined by a guide RNA
Adenine is a purine
true
each base can have two tautomeric forms, which base-pair differently
true
each base has a 3’ OH group
false
glycosidic bonds connect the sugars to the phosphates
false
hydrogen bonds hold the two strands together
true
deoxyribose sugars in the middle of a strand do not have any free OH groups
true
deamination of thymine creates uracil in DNA
false
DNA polymerase slips on the template and causes expansion of a trinucleotide repeat
true
spontaneous hydrolysis of a glycosidic bond cerates an apurinic site
true
a base analog such as a 5-bromouracil causes a single-base insertion
false
x-rays cause chromosome breaks
true
primers used consist entirely of RNA in
prokaryotes
telomerase is needed to complete replication of chromosomes in
prokaryotes and eukaryotes
each origin of DNA replication creates two replication forks
prokaryotes and eukaryotes
chromosomes are organized by wrapping DNA around histone proteins
eukaryotes
transcription of the genes encoding enzymes for the biosynthesis of the amino acid leucine to be
negatively regulated and repressible by leucine
what is a transcriptional enhancer
a DNA sequence distant from a promoter that is a binding site for transcription activator proteins
two adjacent genes on a chromosome are transcribed in opposite directions. this is possible because
the template strands are different
in steroid hormone signaling, the steroid hormone affects transcription by
binding to a steroid hormone receptor, causing it to enter the nucleus where it binds DNA
How does termination of RNA polymerase II transcription in eukaryotes occur?
once RNA polymerase passes the poly-A signal sequence, the RNA is cleaved
what are the types of chromatin remodeling effects?
replacement of some histone proteins with variant histone proteins, deacetylation of histones, methylation of amino acids in the histone N-terminal tails, and changes in the spacing of nucleosomes along the DNA
this large and complex general transcription factor has a DNA helicase activity that exposes the template for RNA polymerase II transcription. It also has a kinase activity that phosphorylates the C-terminal domain of the polymerase
TFIIH
tRNAs are transcribed by
RNA polymerase III
How do transcription activation domains affect rates on transcription initiation in eukaryotes?
they physically interact with the mediator in the pre-initiation complex
phosphorylation controls eukaryotic transcription activators
true
movement to the nucleus controls eukaryotic transcription activators
true
binding of an inhibitory subunit controls eukaryotic transcription activators
true
binding of a small molecule controls eukaryotic transcription activators
true
interaction with a nuclease controls eukaryotic transcription activators
false
glutamine-rich domains is a structural domain found in transcription factors
false
helix-turn-helix is a structural domain found in transcription factors
true
disulfide bridge is a structural domain found in transcription factors
false
zinc finger is a structural domain found in transcription factors
true
leucine zipper is a structural domain found in transcription factors
true
DNA replication and transcription require topoisomerase activity
false
DNA replication and transcription require a DNA template
true
DNA replication and transcription require a primer to initiate synthesis
false
DNA replication and transcription require ribonucleoside triphosphates
true
DNA replication and transcription require specific sites in the genome to start
true
tryptophan binding to the trp repressor protein reduces the rate of transcription initiation on the trp operon
true
formation of a hairpin loop including regions 3 and 4 of the attenuator reduces the rate of transcription initiation on the trp operon
true
formation of a hairpin loop including regions 2 and 3 of the attenuator reduces the rate of transcription initiation on the trp operon
false
absence of tryptophan reduces the rate of transcription initiation on the trp operon
false
a ribosome stalling on the trp codons in the leader peptide reduces the rate of transcription initiation on the trp operon
false
transcription and translation occur simultaneously in prokaryotes and eukaryotes
false
mediator is a part of the transcription initiation complex in eukaryotes but not in prokaryotes
true
in both prokaryotes and eukaryotes, RNA polymerases contain multiple different subunits
true
in both prokaryotes and eukaryotes, rRNAs and mRNAs are produced by different RNA polymerases
false
regulation of transcription in both prokaryotes and eukaryotes involves proteins that bind to specific DNA sequences to increase or decrease transcription levels
true
