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Cell Bio Exam 2
Terms in this set (41)
Which of the following would NOT be a way that a cell could store potential energy to use later?
Accumulation of O2 on one side of a membrane
Which of the following would NOT happen in a cell?
Channels produce active transport
You have constructed phospholipid vesicles that contain Na+/K+ pumps as the sole membrane protein. The portion of the pump that normally faces the cytosol is oriented towards the outside of the vesicles. The solutions inside the vesicles and outside the vesicles have only Na+ ions but NO K+ ions, and ATP is present only on the outside of the vesicle. What would happen?
Very little Na+ would move inside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the inside of the vesicle)
A transmembrane protein has two binding sites - one for solute A and one for solute B. Either both sites are exposed on one side of the membrane, or both sites are exposed on the other side of the membrane. The protein can switch between these two conformational states only if one binding site is occupied, but not if both binding sites are occupied or if both binding sites are empty. The protein is
an antiport carrier protein
Protons are pumped by (1) to accumulate high levels of protons in the (2) for generation of ATP, while NADPH is generated by movement of electrons through __(3)
Photosystem II (1), Thylakoids (2), Photosystem I (3)
Place the electron transport carriers in order for the mitochondrial electron transport, from the one with lowest redox potential (most tendency to give up electrons; first) to the one with the highest redox potential (least tendency to give up electrons; last)
NADH-coenzyme Q oxideductase, Coenzyme Q-cytochrome C oxieductase, Cytochrome C oxidase
Which of the following electron carriers has the highest redox potential (most tendency to hold onto electrons)?
Which of the following mechanisms can be used to pump protons across the inner membranes of mitochondria?
Pumps switch to a low energy state when they bind a proton in the matrix, gain energy in response to the transport of electrons, and then change to a low affinity state for the proton in the intermembrane space.
Placement of an electron acceptor on the inside of the inner mitochondrial membrane and an electron donor on the outside can move a co-transported proton to the outside
Which of the following conditions would provide the most favorable conditions for the synthesis of ATP by ATP synthase in mitochondria?
proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and low ATP/high ADP in the matrix.
You have generated two sets of vesicles, both with bacteriorhodopsin (which pumps protons out of bacteria in response to light) and the mitochondrial F1 ATPase inserted into the membranes of the vesicles. In both cases, the parts of the proteins that normally face the outside of the cell or the mitochondrial intermembrane space are inside the vesicles, and protons, ADP and inorganic phosphate are outside the vesicles. Both sets of vesicles are incubated with light, but one set also has an uncoupling agent present. What will each of the two vesicle sets do?
The set without the uncoupling agent will pump protons and generate ATP, while the set with the uncoupling agent will pump protons but will not generate ATP
What would happen if the membrane of a cell at resting membrane potential suddenly became highly permeable to Na+ ions?
The membrane potential would change from negative to positive (and vise versa)
What explains the following higher amplitude peak in the patch clamp recording of a piece of membrane?
A second in the channel in the patch opens while the first channel stays open
Which of the following would lead to the most depolarization of a neuronal membrane?
Binding of high levels of acetylcholine to the nicotinic acetylcholine receptor
The opening of which of the following channels tends to induce opening of more channels of the same type?
the voltage-gated Na+ channel
What causes a voltage-gated Ca++ channel to open, thereby signaling neurotransmitter release?
A change in membrane potential from a negative to a more positive value
Which of the following would NOT be found on a vesicle that has just started to interact with its acceptor compartment?
a coat protein
Clathrin-coated vesicles can be formed in vitro when adaptins, clathrin and dynamin-GTP are added to eucaryotic plasma membrane fragments. What would happen if you left adaptins out of the in vitro reaction but included the other components?
Clathrin coats would not assemble around patches of membrane and buds would not form
Which of the following is NOT a destination of a transport vesicle produced in the Golgi apparatus?
another cisterna of the Golgi apparatus
the plasma membrane
all of the above
Proteins which aggregate
In the ER are targeted for degradation, but in the Golgi are targeted for regulated secretion.
After dissociation of the LDL particle and the LDL receptor in the endosome, the LDL particle is _(1) and the LDL receptor is typically ___ (2)
degraded in the lysosome (1), returned to the plasmas membrane (2)
Which of the following does (do) the increasingly acid pH of the endosomal to lysosomal pathway NOT produce?
Activates the enzyme which adds mannose-6-phosphate to proteins.
Which of the following components of a Multivesicular Body (MVB) is NOT degraded?
external MVB membrane (one side facing the cytosol)
The lysosome degrades which of the following?
an extracellular ligand taken up by endocytosis
a bacterium taken up by phagocytosis
a damaged mitochondrion taken up by autophagocytosis
all of the above
Using genetic engineering techniques, you attach an N-terminal cleaved ER signal sequence to a protein that also has a nuclear localization signal in the middle. What will happen to the protein?
It will be translocated to the ER
Predict the membrane orientation in the endoplasmic reticulum (ER) of a protein that is synthesized with an N terminal cleaved ER signal sequence, followed by a stop-transfer sequence and then a start transfer sequence in more C terminal regions of the protein (with no more stop transfer sequences). Going from the N terminus to the C terminus, the orientation would be:
N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen.
A difference between transport of proteins into mitochondria and transport of proteins into the ER is
transport of proteins into mitochondria occurs post-translationally, while it occurs cotranslationally into the ER.
transport of proteins into mitochondria must occur across two lipid bilayers, while it occurs across one lipid bilayer into the ER.
Excision DNA repair systems involve
Single-stranded breaks in the damaged strand on each side of the damage and resynthesis of the damaged DNA strand between the breaks
Transcription takes place in single-stranded DNA bubbles that differ from DNA replication bubbles because
transcription bubbles do not expand in both directions.
transcription bubbles do not transcribe all of the genomic DNA.
transcription bubbles do not use both strands as template.
transcription bubbles produce a single-stranded product (RNA, not DNA).
During translation, proofreading (e.g., proceeding only if the correct tRNA is bound with the mRNA codon) occurs when...
GTP is cleaved by EF-Tu.
Which of the following is NOT required for initiation of transcription by RNA polymerase II in eukaryotes?
an RNA primer synthesized by another enzyme
In the splicing reaction, the 2' OH of an A in the intron reacts with a ribonucleotide at the __ to form a lariat structure.
5' end of the intron
Approximately 200 adenosines are added
the 3' end of most mRNA's
Which of the following is a TRUE statement about translation?
The small subunit of the the ribosome initially binds with initiation factors that bind to the 5 methyl guanosine cap
Place the following steps for translation in order, from first to last
Amino acid charged tRNA binds at the A site, peptide bond synthesized between peptide at P site and amino acid at A site, small ribosome subunit moves forward on mRNA, tRNA expelled from E site.
What binds to a nuclear localization signal in the sequence of a nuclear protein during nuclear transport of this protein from the cytosol to the nucleus?
a nuclear import receptor
Which of the following DNA repairs typically involves removing deoxyribonucleotide from either strand of the DNA molecule - not just the most recently synthesized strand?
Which of the following is (are) a correct description of a microtubule-dependent process involved in mitosis?
A. Kinetochore microtubules shorten from their + ends and dynein motors move their attached chromosomes toward their - ends (centrosome).
B. Kinesins move elongating interpolar microtubules along each other to push poles away from each other.
C. The aster microtubule dynein motors pull the poles (e.g., the centrosomes) towards the cell cortex,
All of the above
In the anaphase promoting complex, _(1) is degraded, and this activates (2) to cleave __(3) that hold the sister chromatids together
securing (1), separase (2), cohesiones (3)
DNA polymerases add new nucleotides to the (1) end of a growing strand while hydrolyzing a phosphoanhydride bond on the___(2) end of the added nucleotide to remove an incorrectly added nucleotide
3' (1), 5' (2)
Why does every DNA replication fork generate leading and lagging replication strands?
because DNA is an antiparallel double helix
A newly replicated DNA strand in a replication bubble with two forks is
leading strand on one side of the bubble and lagging strand on the other side
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