AAMC FL 2 BB exam questions fully solved & verified for accuracy 2024

The information in the passage suggests that in mice CRY1 most likely affects XPA by: A.activating XPA protein activity. B.activating translation of XPA-encoding transcripts. C.repressing replication of the XPA-encoding gene. D.repressing transcription of the XPA-encoding gene. passage: the nucleotide excision repair system (NER) recognizes, removes, and replaces segments of DNA strands that contain CPDs and (6-4) PPs. Figure 1 shows how mouse skin levels of XPA (a damage-recognition and rate-limiting factor in NER) and clock regulatory protein CRY1 D. the graph shows that while CRY1 is up, XPA levels are down. so it is going to depress the activity. XPA is said to be a damage-recognition and rate limiting factor in NER, therefore you can deduce that it is going to be an enzyme=protein=transcription. Which cells harvested from adult mice were most likely used as the highly proliferative benchmark in the experiment that generated the data shown in Figure 3? A.Adipocytes B.Cardiac muscle cells C.Gastrointestinal epithelial cells D.Neurons Key word here is proliferative. Proliferative cells grow or multiply by rapidly producing new tissue, parts, cells, or offspring. This happens A LOT in the stomach. POE: A- no. mature adipocytes do not divide B- cardiac MUSCLE cells do not divide once matured. D- neurons NEVER divide. Once you lose a neuron, it's gone forever. After a section of a DNA strand containing a UVR-induced lesion is removed and resynthesized, the newly synthesized strand is rejoined to the remainder of the DNA strand by what type of bond? A.Disulfide B.Hydrogen C.Peptide D.Phosphodiester Dna is joined together by phosphodiester bonds :) Which image shows an example of a cyclobutane pyrimidine dimer? Remember: pyrimidines are one ring. purines are two rings. Dimer=2 fused together. AlP exposed to an aqueous solution in which pH range will result in the largest amount of PHOSPHINE production? A.pH < 4 B.4 < pH < 7 C.7 < pH < 10 D.pH > 10 equation: AIP + 3H+ ---->AI+ + 3PH3 according to lechatlier's principle, when you increase the 3h+ (making PH hella acidic) the equation is going to shift to the right and make more phosphine. Based on the passage, which amino acid will most likely react with phosphine? A.Met B.Cys C.Ser D.Thr passage: It is thought that phosphine reacts with important sulfhydryl groups cysteine has sulfhydryl groups and can make disulfide bonds. Methionine is the other amino acid that is sulfur containing, but cannot make disulfide bonds. Therefore cysteine is the correct answer. When researchers determined the total cellular concentration of ATP in AlP-exposed rat liver cells, they found the concentration to be equal to the control value. Which conclusion about the metabolic state of the cell is best supported by these data? A.Glycolytic flux is increased after AlP treatment. B.Glycolytic flux is decreased after AlP treatment. C.Citric acid cycle flux is increased after AlP treatment. D.Citric acid cycle flux is decreased after AlP treatment. passage: It was found that AlP exposure resulted in a 65% decrease in ATP levels and a 48% decrease in the rate of ATP synthesis. In addition, the effect of AlP on the activity of three ETC complexes was determined (Table 1). The activities of these complexes were determined independently of each other. Mitochondrial ATP synthesis has been decreased based on the passage and the data in the table. Therefore, most of the app that will be made will have to be in the cytosol outside of the mitochondria. This indicates that there will be an increase in glycolytic flux after AIP treatment. REMEMBER: ATP is NOT directly produced by the citric acid cycle. Those answer choices should be immediately crossed out. Why was it necessary for the researchers to determine the activity of the complexes independent of one another? A.Complex stability is lost if the complexes are able to interact structurally. B.The complexes have different cellular locations, and it is not feasible to isolate them together. C.The complexes all use the same substrates, so their use must be monitored separately. D.The reactions catalyzed by the complexes are coupled to one another. POE: A- no this makes absolutely no sense. B- no they are all located in the inner mitochondrial membrane where oxidative phosphorylation takes place. C- they DO NOT use the same substrates. Complex two starts using fadh2 whereas complex one does not use FADH2 at all. D- Absolutely. inhibition of complexes I and II affects the activity of Complex III, which affects the activity of Complex IV A large carbohydrate is tagged with a fluorescent marker and placed in the extracellular environment around a macrophage. The macrophage ingests the carbohydrate via phagocytosis. Which cellular structure is most likely to be fluorescently labeled upon viewing with a light microscope soon after phagocytosis? A.Nucleus B.Golgi apparatus C.Lysosome D.Endoplasmic reticulum Okay steps: macrophage eats the shit macrophage need to breakdown the shit because it is dangerous. macrophage needs help from organelle that can break down the shit. This organelle is the lysosome. Inhibition of phosphofructokinase-1 by ATP is an example of: allosteric regulation. feedback inhibition. competitive inhibition. A.I only B.III only C.I and II only D.II and III only Absolutely feedback inhibition. (cross out A and B) This is absolutely not competitive inhibition. ATP does NOT bind to the active site. It binds to a spot other than the active site when is known as the allosteric site. Which process moves chlorine ions into the cells of the green algae? A.Osmosis B.Diffusion C.Active transport D.Facilitated diffusion graph shows that chlorine is higher inside of the cell than outside of the cell. Chlorine is a negatively charged ion. It is going to use active transport to need to get into the cell! ions must be moved into the cell against their concentration gradient, which requires energy. ------> active transport. Dendrotoxin from the mamba snake blocks voltage-gated potassium channels in somatic motor neurons that regulate skeletal muscle contraction. In what way would initial exposure to dendrotoxin affect the ability of a somatic motor neuron to propagate an electrical signal in response to a stimulus? A.It would inhibit the initiation of an action potential. B.It would shorten the refractory period. C.It would prolong the action potential. D.It would prevent depolarization. VG potassium (k) channels are related to hyper polarization of action potential. hyperpolarizing is stopping the action potential of the cell. POE: A- this would happen if the question said Na+ channels, not K+ B- actually it would prolong the refractory period. refractory period happens right after stimulation. C- YES! the action potential would continue on until hyper polarization occurs. If the VG K+ channels are turned off, then hyper polarization won't happen. D- is essentially saying the same thing as A. Based on the passage, which statement describes Wnt proteins? A.They are composed of multiple subunits. B.They have a positive charge. C.They are synthesized in the smooth endoplasmic reticulum. D.They fold into their tertiary structure in the cytoplasm. Passage: Wnt proteins are a family of palmitoylated secretory proteins with isoelectric points around 9 that bind and activate the G protein-coupled receptor Frizzled, whose structure includes seven transmembrane α-helical domains. Isoelectric point is around 9. This means that the protein will be protonated at pH 7. protonated= positive charge! Based on the passage, β-catenin most likely has: A.multiple subunits. B.very few disulfide bonds. C.a nuclear localization sequence. D.a high proportion of surface-exposed nonpolar residues. passage: and β-catenin, which activates expression of Wnt target genes. CK1 and GSK3 sequentially phosphorylate β-catenin, which targets it for ubiquitination. Figure one shows that it is activating transcription factors. Activating transcription factors needs a nuclear localization sequence. ubiquitination ubquitination triggers proteolysis via a proteasome In the absence of Frizzled activation, β-catenin is covalently modified and: A.bound by a proteasome to initiate degradation into short peptides. B.translocated into the Golgi body for secretion through exocytosis. C.engulfed by a lysosome where it is hydrolyzed by proteases. D.stored in vesicles until the signaling pathway is activated. Passage: CK1 and GSK3 sequentially phosphorylate β-catenin, which targets it for ubiquitination. Ubiquitination= proteolysis via a proteasome. Ubiquitination= proteolysis via a proteasome. This goes directly with answer choice A.