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
