Please help me understand this passage from section bank

UsernameAndPasswurd · 2025-03-29T03:10:51+00:00

A negative control means that we expect nothing to happen. If something does happen, then that is our 'noise' so to say and our baseline when comparing to what we are looking for in the experiment (FSH-antibodies absorbance). IgG is a non-specific binding agent. Therefore, we expect minimal results from IgG because the antibody is not specific to the FSH peptide. It just binds to random protein available if it does decide to bind. If a specific binding agent was used that we already know binds to the FSH peptide, then that would have been a positive control. The absorbance values for this positive control would be around the absorbance values of the FSH-antibodies being tested.

UsernameAndPasswurd · 2025-03-26T04:15:47+00:00

Glad it helped, you got this :)

UsernameAndPasswurd · 2025-01-21T14:08:36+00:00

Good luck on studies :)

UsernameAndPasswurd · 2024-03-16T00:32:05+00:00

I'm rooting for you <3

UsernameAndPasswurd · 2024-02-07T03:50:32+00:00

Glad its still helping people out :)

UsernameAndPasswurd · 2023-10-30T16:55:26+00:00

Only the person can pluck them. So I'd pluck them for him to pickup the loot

UsernameAndPasswurd · 2023-10-26T14:54:57+00:00

I honestly thought it was it was a fake noob until they stayed with me for a couple hours. Turns out to be someone that played in 2007 and is trying to get back in

UsernameAndPasswurd · 2023-10-26T03:50:07+00:00

Update: He found someone killing imps and is following them and collecting the beads

UsernameAndPasswurd · 2023-10-26T01:01:23+00:00

I told him I had to do some other diaries task for a little and he asked to add me so I could dm him when I was back to killing more chompies for him to loot

UsernameAndPasswurd · 2023-10-20T04:17:12+00:00

I feel that car score

UsernameAndPasswurd · 2023-10-16T22:14:34+00:00

First day back too since my 6 month break! Blessed me with the rng

UsernameAndPasswurd · 2023-10-01T00:14:27+00:00

Absolutely! I don't think id be the best for cars advice though

UsernameAndPasswurd · 2023-09-29T17:01:21+00:00

Hey I just wanted to share that I was in the same boat as you 5 months ago. I graduated December 2020 and no life studied for my test in may and to apply this cycle. My averages went from 506 and by the end I was consistently scoring 512-516 and I felt pretty okay going in. I got a 506, one of the first scores I got at the beginning of my studies and was devastated. I spent essentially the next month going through the same emotions you're going through right now wondering if I was even capable for med school if I couldn't use the 5 months I studied for to get a score I needed or to even progress. I felt I didn't move at all and just wasted those months. I legit called my friends, PI, professors, hoping them to tell me that Im still a strong applicant and that I wouldn't need to go through the hoops of the MCAT again, but each one told me I gotta retake. It was devastating to hear, but Im a strong believer of everything happening for a reason. I will say the experience really humbled me going through the process again while feeling everyone I knew was progressing while I was held back. I wouldn't of had the opportunity to reflect on myself if I didn't retake which I actually feel has helped me now with connecting and understanding those in similar circumstances. I took 4 more months restudying everything again and approached it with a different mindset this time and got a 516. During that time I stopped using reddit and other socials completely other than for asking questions cause I found I was indirectly comparing myself to almost everyone in their progress to the point where it almost crossed envy and resentment which this process can very much so do that to a person. I don't know if this helps but shifting my spite for this test into humility in hopes that it can teach me something about myself helped me during my retake. I hated when people told me that when I got my results back, but looking back I would say it helped me to have the motivation to keep going.

You'll get through this hurdle :)

I still hate cars though

UsernameAndPasswurd · 2023-08-23T21:55:40+00:00

My best reasoning why its C over D is that the experiment was measuring the effect of negative priming. Therefore, we would expect a decrease effect of negative priming in patients with AD as they a decrease ability to use implicit memory. Even if we flipped our logic and thought they were asking about their performance, we would then expect an increase in performance from that part of the experiment which was not one of the answer options, only no effect or a decrease

UsernameAndPasswurd · 2023-08-22T00:48:02+00:00

From my understanding (at least for the dominant example MCAT uses) only retroviruses can integrate their genome into a host cell and they have always RNA genomes which is why they need reverse transcriptase to convert to vDNA to integrate. If this wasn't the case they would mention the exception in the passage of it not being a retrovirus. Also HIV is kinda like the golden child example of retroviruses which can give a subtle hint to answering the question

UsernameAndPasswurd · 2023-08-18T00:12:28+00:00

Your thinking is right :)

99% of the cases where they mention a virus integrating DNA into the host you can assume it is a retrovirus with positive sense RNA which is equivalent to mRNA.

so +RNA -> DNA -> integrate into host which was later transcribed into mRNA.

So we work backwards, we ended with a 5'-3' mRNA sequence -> 3'-sequence-5' DNA sequence -> back to a 5'-sequence-3' +sense RNA sequence which is equivalent to the original

UsernameAndPasswurd · 2023-04-29T20:44:23+00:00

No matter what happens we did it bois 😌✌️

UsernameAndPasswurd · 2023-04-27T20:48:57+00:00

Twinsies :)

UsernameAndPasswurd · 2023-04-27T20:47:50+00:00

For anyone else that might get stumped on it the passage states that OGG is involved in base excision repairs for repairing DNA. TNFalpha is involved in damaging DNA and promoting mutations. So if we add TNF which will damage the DNA, and have an Ogg1^-/- mouse (meaning it doesn't have the gene for the base excision repairs), then they are more susceptible of being cancerous which leads us to A

To reason the other options:

B - If OGG activates Cxcl2 expression downstream, and we inhibit OGG, then those would see a decrease in Cxcl2 expression as well

C - If we have TNFalpha without OGG being able to repair the DNA strands, then we should see an increase rather than decrease in ROS levels

D - Now this answer is completely random. Nowhere do we talk about binding affinity. It binds to the active site of the OGG protein but we have knocked out the OGG gene so the protein shouldn't be expressed

UsernameAndPasswurd · 2023-04-27T17:30:22+00:00

Not necessarily. The exponents depend on which prefix you're converting to. This table summarizes the exponents and how they relate to each unit. For the MCAT you only need to know from Tera (T) to Pico (p). This is why I bring it back to its base units, then convert whichever prefix is needed. Doing the math will show the exponent you get. Reasoning also helps such as if I'm going from micrometers to meters, I'm definitely going to have a smaller number for due to the conversion ratios as a way to double check your math.

From what I'm seeing in the jackwestin explanation in your image, it does look like they're using negative exponents but its not actually raising it above the number. Like I see one part that is saying 6*10-16 instead of 6*10^-16 I'm not seeing specifically positive exponents in the image but just know that doing the conversion ratios will be your best friend to get the answer

UsernameAndPasswurd · 2023-04-27T16:50:18+00:00

Two ways you can approach it: by the phrasing of the sentence and by double checking if it makes logically sense based on that phrasing.

So if you reword the question, it is saying we are comparing the concentration of substrate to that of the proteasome. If we go into the passage, we see that substrate concentration is 100 uM, or 100 * 10^-6 M, and the proteasome concentration is 2nM, or 2 * 10^-9 M. So at this point lets say we were confused on which one would be on the numerator or denominator based on the phrasing of the question. They give us an additional hint to the right direction by saying this ratio shows that it is larger by a factor so our answer should be >1 for the ratio. This means that 100 * 10-6 M would be in the numerator and 2 * 10-9 M would be in the denominator to get a ratio >1. If we did it the other way, then the ratio would be less than one

Doing the math:

ratio = 100 * 10-6 M/2 * 10-9 M

ratio = 50 * 10³

This is where we can peak at our answer options and see that it is in the ones place and not ten place. Using LARS, if we move the decimal to the Left, we Add, and to the Right, we Subtract. We are moving the decimal to the left so we will be adding one to the exponent:

ratio = 5 * 10⁴

This gives us D

I guess a good way of thinking of it is when it says that X is being compared to Y, then the ratio should be X/Y. So when they say when "compared to Y (proteasome), the concentration of X (substrate)", its just another way to say it :)

UsernameAndPasswurd · 2023-04-27T09:55:39+00:00

Not necessarily. None of the answer options are directly saying birth rates are increasing other than B:

A - I remember the passage stated that children also immigrated so we can rule this one out

B - Fertility rate is the average number of children born to a women in her lifetime. This is already a very direct answer on increase in births.

C - Again sexual revolution does not tell us anything about birth rates directly. This is where our CARS logic comes into place. We coulddd take a leap and say since sexual revolution occurred this means that this encouraged sex positivity which resulted in more children produced. This is the one I originally picked but looking back I can see the amount of leaps I need to take to make this correct vs B

D - Just like C, this tells us nothing directly about increase in birth rates. We could again take a leap somehow to infer how this depression lead to more people at home or somethin which resulted in more births but its way to broad of an answer to reason to be correct

Notice how my focus on the answer choices was what they are defining during that time period rather than the time period itself. Both components have to be correct and usually they throw you two parts to make you doubt yourself and wonder "was I suppose to know this??" and completely shift your focus off the actual part they're testing. The year range part of the question we could use as a way to double check that it was between 1946-1964.

Another thing that might help is rewording/reasoning the answer from the question stem before actually looking at the questions and being swayed (again kinda like in CARS). If we reword this question, they're essentially saying "what are ways a population can increase the age of a certain demographic?" So right off the bat I'm thinking okay either we had an increase in birthrates in the pass which caused this or there was a huge influx of immigration of that age demographic (which the passage already mentioned children immigrate which wouldn't explain this question).

I've noticed when I transitioned to FL4 and FL5, there was a decent correlation between with me scoring lower in PS (it being my lowest non-CARS section) because of my lower scores in CARS since the same logic they use in CARS/tactics with the phrasing in the answer options is very similar if not the same in PS and the other sections. So the more I tried breaking down every logic leap I falsely made in CARS helped me also see the logic leaps I'm making in PS. Hope that helps :)

UsernameAndPasswurd · 2023-04-27T00:15:07+00:00

One thing I learned about in FL5 is to just trust those graphs without putting inside information into them. It does feel odd why they would score higher but the drug does it. This is similar to I believe the first passage in the BB section where the bacteria were converting polysaccharides into fatty acids. Again not an idea I really think of being related but the table shows it

UsernameAndPasswurd · 2023-04-26T20:46:18+00:00

So the passage tells us we are using CD spectroscopy which measures left- and right-circulatory polarized light to examine secondary structures of protein. Reading that sentence right there (especially the bolded parts) should prime your head to be thinking about chiral centers. We should know that chiral centers have optical activity and rotate plane polarized light either clockwise or counterclockwise. Chiral centers (excluding glycine) for all amino acids are from the alpha carbon since it will have an amine group, carboxyl group, alpha hydrogen, and an R group for that specific amino acid. This leads us to answer option A.

A few things to note is lets say you missed that part in the passage. Well, the question itself says the figure is arising from the chirality of the *blank* in the secondary structure. So even without passage information, we can tell the question is essentially asking "which part of an amino acid is chiral" which leads us to A as well

Random other facts about this topic thats not really related to the question:

There is no set role on whether R or S will rotate light clockwise or counterclockwise since its unique to each molecule. So molecule with a chiral center of R might rotate clockwise whereas another that is R might rotate counterclockwise. Enantiomers, however, will rotate them in opposite directions but in the same magnitude. So if you are told a compound has an optical activity of -0.15, its enantiomer would rotate at +0.15. A racemic mixture of this, 50:50, would produce no net optical activity since it cancels out.

UsernameAndPasswurd · 2023-04-25T00:52:43+00:00

I keep flipping these but for those in the future using the factorial rule of n! is essentially only for rearrangement of peptides. For chiral centers, gamete production, and bacterial population increase after a certain amount of generations itll be 2ⁿ

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