Cell Bio Quizzes Flashcards
(30 cards)
which of the following is a purine base?
- cytosine
- guanine
- uracil
- thymine
guanine
the role of topoisomerase during replication is to
introduce single stranded DNA breaks to prevent supercoiling
how many origins of replication does eukaryotic chromosome normally have?
many
which of the following codes for proteins?
- sRNA
- mRNA
- rRNA
- tRNA
mRNA
the codon is a combination of how many nucleotides?
3
which steps of eukaryotic gene expression occurs in the cytosol?
translation
among DNA molecules presented below, which one would start melting first if the temperature keeps increasing?
- they all would melt together as the relative number of G-C and A-T pairs does not affect the temp at which DNA strands get separated
- one that has more G-C pairs than A-T pairs
- one that has more A-T pairs than G-C
- one that has equal number of G-C and A-T pairs
one that has more A-T pairs than G-C pairs
in karyotype, chromosomes are usually numbered by…?
their length
how does the cell solve the end problem of linear chromosome replication?
there is a special enzyme that extends chromosome ends
RNA is different from DNA because…
- they may have different bases
- DNA molecules are synthesized from nucleotide monophosphates while RNAs are synthesized from diphosphates
- have different type of phosphate bonds
- DNA strands are anti-parallel while RNA strands are parallel
they may have different bases
in order to be imported into the nucleus, the cytosolic protein has to…
contain a special amino acid motif
for which step of endocytosis the dynamin, a protein also known to be important for mitochondria fission, is responsible?
pinching the endocytic vesicle off the plasma membrane
which nucleotide residue may normally be found at the 3’ end of eukaryotic mature mRNA?
A (ADENINE)
a mature eukaryotic mRNA has a ___ at the 5’ end
cap
which molecule or group is covalently attached to the cytosolic protein targeted for proteasomal degradation?
Ubiquitin
during elongation step of translation cycle, a “charged” aminoacyl-tRNA binds to the vacant ___ on the ribosome
A-site
in which of the following eukaryotic RNAs may the double-stranded RNA element be found?
- in rRNAs
- in mRNAs
- in tRNAs
- in any type of RNA
in any type of RNA
which of the following unwanted DNA modifications is usually found in the tissues of aged patients?
- depurination
- methylation
- thymine dimers
- oxidation
oxidation
which of the following nucleotide modifications that occur in nature may explain the fact that RNA and DNA molecules share all the bases except U and C?
- oxidation
- deamination
- depurination
- alkylation
deamination
for which of the following steps of transcription cycle in prokaryotes the sigma factor is responsible for?
- elongation
- initiation
- is associated w/ RNA polymerase during the entire cycle
- termination
initiation
which protein is covalently attached to the cytosolic part of transmembrane receptor targeted for lysosomal degradation?
ubiquitin
which event in neuronal transmission is disrupted by the toxin from Clostridium tetani?
synaptic vesicle fusion w/ presynaptic membrane
steroid hormone receptors act by…
activating transcription of target genes
the reserved pool of glucose transporters in muscle cells is stored in…
early endosomes
