The only different between this answer choice and answer choice B is the size of the bars in the graph, but with no axis on the graph, these are essentially the same answer. This answer choice incorrectly shows both graphs having equal relative half-lives. Reasoning here is going to be similar to answer choice A.We expect the half-life of erythromycin in adult females to be shorter than the half-life of erythromycin in males. This answer choice incorrectly shows both graphs having equal relative half-lives.Erythromycin is metabolized by estrogen-sensitive P450 enzymes in the liver, so females (higher estrogen levels) will metabolize erythromycin more quickly. This visual correctly shows the shorter half-life in adult females relative to the half-life in males.Erythromycin being metabolized by estrogen-sensitive P450 enzymes within the liver would therefore have a shorter half-life in adult females. Estrogen is a hormone responsible for the appearance of secondary sex characteristics of human females at puberty, and the maturation and maintenance of the reproductive organs in their functional state. Where do we expect estrogen to be more prevalent: in males or females? Females have higher levels of estrogen. In this case, we’re dealing with an antibiotic that is metabolized by estrogen-sensitive P450 enzymes within the liver. When the body detects a new drug/toxin or increased concentrations of a drug, the body increases the concentration of cytochrome P450 to metabolize the drug effectively. The only answer choice that matches this is answer choice A.ģ) This is a pseudo-standalone question, but touches on something we covered in a previous question: P450 enzymes. The hydrogen atom from that hydroxyl group ultimately is exchanged for the phosphate group on ATP. That hydroxyl group attacks the gamma phosphate group: Right away, we can eliminate answer choices B and C because tyrosine has a nucleophilic hydroxyl group we see highlighted above in blue. Our specific question here wants to know what atoms on tyrosine are exchanged for this phosphate group on ATP. The tyrosine kinase receptor transfers phosphate groups from ATP to tyrosine molecules. A kinase is an enzyme that catalyzes the transfer of phosphate groups, and the tyrosine kinase receptor specifically is an example of a receptor enzyme. The author specifically tells us JAK2 is a tyrosine kinase. Answer choice C is our best answer choice.Ģ) This is a passage-based question and we can focus specifically on Paragraph 2 where the author talks about phosphorylation of STAT5b proteins: This is going to be the opposite function of what we’re looking for. While cytochrome P450 itself is reduced, the enzymes function to alter the activity of drugs by oxidizing them. Cytochrome P450 alters the activity of drugs by acting as an oxidizing agent to allow drugs and toxins to be metabolized. Cytochrome P450 enzymes function as monooxygenases. This answer choice matches our breakdown of the question and the cytochrome P450 enzyme background information we went over. This answer choice is describing phosphatases which function to dephosphorylate. We mentioned in our breakdown that we’re looking for an answer choice that deals with redox reactions. Typically, kinases will be the ones phosphorylating proteins in the body. We want an answer choice that deals with redox reactions. They are membrane-bound proteins that enable oxidation reactions. The author introduces cytochrome P450 enzymes in Paragraph 3 and we get some background information:Ĭytochrome p450 enzymes appear a few times in AAMC’s practice material but it’s not explicitly listed on the content outline. 1) This is a passage-related question that functions almost like a pseudo-discrete.
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