Cell Bio most missed questions
Which of the following would yield the most highly mobile phospholipid (listed as number of carbons and number of double bonds, respectively)?
15 carbons with two double bonds
Which of the following molecules is an allosteric inhibitor of this phosphofructokinase?
ATP
Compared to the normal situation, in which actin monomers carry ATP, what do you predict would happen if actin monomers that bind a nonhydrolyzable form of ATP were incorporated into actin filaments?
Actin filaments would grow longer.
Which of the following statements about the unfolded protein response (UPR) is false?
Activation of the UPR occurs when receptors in the cytoplasm sense misfolded proteins.
Molecules to be packaged into vesicles for transport are selected by
Adaptins
Which of the following statements is true?
Disulfide bonds stabilize but do not change a protein's final conformation.
ACh (acetylcholine) is a neurotransmitter that induces different responses in salivary gland cells, heart pacemaker cell, and skeletal muscle cells. Which of the following determines how the cell reacts to ACh?
Effector protein(s)
Direction of passive transport for charged molecules is determined by
Electrochemical gradient
Which of the following organelles glycosylate proteins destined for secretion
Endoplasmic Reticulum Golgi apparatus ANSWER IS BOTH!!!
Which of the following occur without coupling transport of the solute to the movement of a second solute?
Export of Ca2+ from the cytosol
The mitochondrial ATP synthase consists of several different protein subunits. Which subunit binds to ADP + Pi and catalyzes the synthesis of ATP as a result of a conformational change?
F1 ATPase head
T/F: RNA Polymerase can function in either the 5'-to-3' direction or the 3'-to-5' direction when transcribing DNA to mRNA
False, RNA polymerase can only function in the 5'-to-3' direction on the DNA strand
T/F: GTP-binding proteins rely on GTP to regulate their activity. For a GTP-binding protein to shift to the "on" conformation, Pi is added to GDP molecule bound to this protein
False. GTP binding molecule must release GDP and bind to a new GTP molecule to shift to the "on" conformation
During gluconeogenesis, which enzyme catalyzes the formation of fructose 6-phosphate from fructose 1,6-bisphosphate
Fructose 1,6 bisphosphatase
The formation and degradation of glycogen is allosterically regulated by
Glucose 6-phosphate
A poison added to an in vitro translation mixture containing mRNA molecules with the sequence 5′-AUGAAAAAAAAAAAAUAA-3′ has the following effect: the only product made is a Met-Lys dipeptide that remains attached to the ribosome. What is the most likely way in which the poison acts to inhibit protein synthesis? (AGAIN... THINK!!!)
It inhibits movement of the small subunit relative to the large subunit.
The conversion of glyceraldehyde 3-phosphate to 1,3 bisphosphoglycerate in step 6 of glycolysis generates a "high-energy" phosphoanhydride bond. Which of the following BEST describes what happens to that bond in step 7?
It is hydrolyzed to drive the formation of ATP.
NADH and FADH2 carry high-energy electrons that are used to power the production of ATP in the mitochondria. These cofactors are generated during glycolysis, the citric acid cycle, and the fatty acid oxidation cycle. Which molecule below can produce the most ATP? Explain your answer.
NADH from the citric acid cycle
What is the energy source for the glucose uniport
None, it is passive transport
You are studying nuclear lamins in yeast. Using recombinant DNA technology, you alter the coding sequence of a nuclear lamin gene such that the gene now codes for a nuclear lamin protein that can no longer be phosphorylated when the nuclear envelope is broken down during mitosis. What do you predict would happen if the yeast cell only had the altered nuclear lamin gene (and not the unaltered version)? (THINK!!!)
Nuclear lamins will no longer disassemble properly during mitosis.
Which of the following best describes the formation of phosphodiester bonds in polynucleotides
Occurs between a phosphate group and 2 pentose sugars
Which of the following components of the electron transport chain have the highest affinity for electrons
Oxygen
Which of the following describes how Mycobacterium tuberculosis prevents phagocytosis by macrophage
Prevents phagosome fusion with lysosome
Pyruvate must be decarboxylated to Acetyl-CoA prior to entry to the citric acid cycle. Which of the following complexes catalyzes this reaction?
Pyruvate dehydrogenase complex
If you take amylase (an enzyme found in saliva with a pH of 6.5) and introduce it to stomach acid (pH of 1-3.5), the protein shape becomes disrupted and denatured. Which of the following best describes how this occurs
The pH causes disruption of the non-covalent interactions between various regions of a protein
The Na+-K+ ATPase is also known as the Na+-K+ pump. It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydrolyzes ATP?
The pump is phosphorylated
Which one of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon?
The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter.
NADH produces more ATP than FADH2 because
They donate electrons to NADH dehydrogenase
Which of the following might decrease the transcription of only one specific gene in a bacterial cell?
a mutation that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site
You are interested in cell-size regulation and discover that signaling through a GPCR called ERC1 is important in controlling cell size in embryonic rat cells. The G protein downstream of ERC1 activates adenylyl cyclase, which ultimately leads to the activation of PKA. You discover that cells that lack ERC1 are 15% smaller than normal cells, while cells that express a mutant, constitutively activated version of PKA are 15% larger than normal cells. Given these results, which of the following treatments to embryonic rat cells should lead to smaller cells?
addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive
Energy required by the cell is generated in the form of ATP. ATP is hydrolyzed to power many of the cellular processes, increasing the pool of ADP. As the relative amount of ADP molecules increases, they can bind to glycolytic enzymes, which will lead to the production of more ATP. The best way to describe this mechanism of regulation is
allosteric activation
Your friend has just joined a lab that studies vesicles budding from the Golgi and has been given a cell line that does not form mature vesicles. He wants to start designing some experiments but was not listening carefully when he was told about the molecular defect of this cell line. He is too embarrassed to ask and comes to you for help. He does recall that this cell line forms coated pits but vesicle budding and the removal of coat proteins don't happen. Which of the following proteins might be lacking in this cell line? (*THINK*)
dynamin
The concentration of H+ ions inside the mitochondrial matrix is lower than it is in the cytosol or the mitochondrial intermembrane space. What would be the IMMEDIATE effect of a membrane-permeable compound that carries and releases protons into the mitochondrial matrix? (think)
inhibition of ATP synthesis
Which of the following is not a function of chaperone proteins inside the mitochondria
Capture misfolded proteins before exportation
Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?
Cell division
To produce the correct mRNA sequence to produce the correct protein in a cell, the cell must determine which strand of the DNA double helix to use as the template strand. Which of the following help determine which strand is the template strand
The Promoter region has a specific polarity that positions the RNA polymerase in the correct orientation on the correct template strand
The ribosome is important for catalyzing the formation of peptide bonds. Which of the following statements is TRUE?
The catalytic site for peptide bond formation is formed primarily from an rRNA.
