AAMC Section Bank BB and CP

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lotus0618
Posts: 182
Joined: Sun Dec 29, 2019 5:47 pm

AAMC Section Bank BB and CP

Post by lotus0618 » Thu Jul 16, 2020 7:36 pm

B/B Passage 5 question 38:
Please check if my understanding is correct?
A. the passage doesn't mention anything about the antibody.
B. Intuitively this answer plainly doesn't sound right to me. I think this is the job of Adolase. Can you please explain to me the role of Adolase in this experiment?
C. VopC activates Rac. This is not about the rates of activation. It's about whether active VopC can turn on Rac.
D. I chose this one because without the control "total Rac," we wouldn't actually know if the inactivation of Rac is due to VopC or is the Rac absent, to begin with. If the total Rac were to show the no Rac, then we wouldn't be able to tell if VopC activates Rac.

B/B Passage 6: Question 42

I chose D immediately and sent like 3 seconds on it. Now the answer is C alanine. I have 2 questions for this answer:
1) I interpret this question as finding a substitute for the residue in the WILDTYPE, not the variant. How am I supposed to know that this question is asking for a residue that is similar to the variant in which it cannot be phosphorylated?
2) THere's this saying "You don't know what you don't' know." To me my consistent test-taking pattern has been "You dont remember what you dont' remember" Under time constraint, I didn't remember about the inability to be phosphorylated of the residue. I have missed many questions not because of lack of knowledge, but due to not remembering the clue. While reading the passage, i didn't skim and made a map of those connections. The info that I didn't take note tend to be the one that I'd forget. If i come across a question that asks for that piece of info, I tend not be aware of another piece of info required to answer the qusetion. How can I not make this mistake again?

C/P Passage 5: Question 40

I chose the correct answer because I know like other carboxylic acid derivative reactions, the intermediate is always tetrahedral with the nucleophilic attacks the carbonyl, making it sp3. However, can you please explain to me this question? I'm having a hard time visualizing it.

CP Passage 6:

Question 44: How do you know that figure 1 implies a 1:1 mole ratio? I wasn't aware of this and used the values (volume and Molarity) of NAG3 to find its mol.
Q 46: How I understand this question is that Kapp now has a stronger binding affinity compared to K1 in the presence of compound 2. With this understanding, none of the answers makes sense to me. :/
Can you please explain question 46 to me? thanks a lot
NS_Tutor_Yuqi
Posts: 53
Joined: Fri May 29, 2020 11:43 pm

Re: AAMC Section Bank BB and CP

Post by NS_Tutor_Yuqi » Sun Jul 19, 2020 1:08 pm

CP 40: You described it well! The carbonyl carbon originally has an sp2 configuration, which turns into sp3 as it goes into the tetrahedral intermediate, which then reverts back to sp2 after the amine is eliminated. Keep in mind that we're talking about peptide bond hydrolysis here, so don't let yourself get caught up in the jargon of the passage.

44: Since we know that the equivalence point is halfway up the titration curve, seeing the graphs in Figure 1 should clue you in to the fact that they're necessary for finding the equivalence point. You can see on the left graph that the equivalence point is reached at a 1:1 molar ratio.

46: One way to solve this is by using Equation 1: KNAG3/Kapp = 1 + KNAG[NAG]. Assuing that NAG3 is the Compound 1 and NAG is Compound 2, you want to create a situation where Kapp < K1 (or KNAG3 in the equation). In order to do that, you need a greater value on the right side of the equation, which can be accomplished by increasing the concentration of Compound 2 (or NAG in the equation). Additionally, you can use Figure 2, which essentially gives you the same relationship that KNAG3/Kapp increases as [NAG] increases, which means that Kapp is progressively getting smaller than KNAG3.

BB38: The passage tells us that aldolase is a constantly expressed protein in the host cell, which means that it serves as a positive control.
A. the passage doesn't explicitly talk about the antibody, but we know antibodies were used since they did a western blot. The reason why this is wrong is because an antibody for GTP-Rac wouldn't detect total Rac. I agree with the rest of your reasoning.

42: The question starts with "When designing variant CREB327119", which tells us that we are trying to design a form that cannot be phosphorylated. To not make the same mistake again, it's good practice to refer back to the passage when you're answering the question, just to make sure that you remembered everything correctly. Since the question asks about residue 119, you should go back to the passage and find wherever it talks about that residue.
lotus0618
Posts: 182
Joined: Sun Dec 29, 2019 5:47 pm

Re: AAMC Section Bank BB and CP

Post by lotus0618 » Sun Jul 19, 2020 2:04 pm

For question 46: how could you even think of making an assumption that NAG3 is compound 1 and NAG is compound 2?
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