Cell Bio Quizzes Flashcards
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
adrenal cells release hormone norepinephrine into the bloodstream that acts on various organs and systems throughout the cell body. this type of signaling is called…
endocrine
early endosome-specific proton pump that acidifies the organelle was blocked by some drug. As a result, the endosome’s pH appeared to be neutral. What would most likely be the consequence of such pH change for the iron transport inside the cell?
neither iron nor transferrin will dissociate from the receptor at the neutral pH, so the whole complex will be returned back to the cell surface without releasing the iron inside the cell
omega-3 fatty acid is a component of…
phosphatidylinositol phosphates
a number of which of the following intracellular structures or organelles may be increased in cancer cells?
- intermediate filaments
- Clathrin-coated pits
- Golgi stacks
- ER-associated ribosomes
Clathrin-coated pits
the role of glucosyltransferase in the ER protein quality controls cycle is to…
add glucose residues to the misfolded protein so that the chaperon may help the protein to fold again
the delivery of newly synthesized proteins across the mitochondrial membranes involves…
membrane translocases
