The Official 4/26/13 MCAT Thread

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In lieu of the other threads popping up, I thought it'd be good for those of us taking the test to identify ourselves 👍

I'm not planning on following a rigid study schedule until January, but I think I'm going to watch a single video off of wikipremed daily to lightly review.

Good luck to everyone... we will crush this exam..

 

[MedGrl@2022]

Yeah, + means has that function. If you inactivate myosin Va, you can't move the melanosome along the cytoskeleton to release it, causing albinism. If you inactivate Rab27a, the melanosome can't bind myosin Va, so the mice are albino, but not necessarily with or without CTL activity. Based on the evidence in the table, they do not have CTL activity either, which must mean that Rab27a is present in lytic granules as well as melanosomes and is necessary for release of lytic granules from CTLs.

Oh so in the passage they only described the mechanism of melanosomes and not CTLs... you can infer which proteins are involved in CTL from table 1, right?

 

[MedGrl@2022]

I suppose it could be, but that was not an answer choice, so you have to deal with the answers given. Isozymes/isoenzymes are typically only different by a few amino acids, not an entire spliced region. I don't know of any examples, but I can't rule it out either. Usually, each isozyme has its own specific tissue, and many tissues have only certain regions of DNA open for transcription (as a result of differentiation), so it would make sense that each isozyme specific to a tissue would have its own promotor region and thus a DNA region separate from the other isozymes. I think that questions like these are better off deducing from the answers given rather than inducing from the evidence provided, especially when the topic is unfamiliar.

cool thanks! 🙂 I really appreciate your help! 🙂

 

[WSHRocks]

Oh so in the passage they only described the mechanism of melanosomes and not CTLs... you can infer which proteins are involved in CTL from table 1, right?

Yes. The passage implies that the fundamental functions of each is the same (granules made to be exocytosed), but it only describes the process for melanosomes. Any further speculation on the topic requires the table given in synthesis with what was mentioned in the passage.

 

[MedGrl@2022]

Yes. The passage implies that the fundamental functions of each is the same (granules made to be exocytosed), but it only describes the process for melanosomes. Any further speculation on the topic requires the table given in synthesis with what was mentioned in the passage.

awesome! sometimes I try to think that AAMC is suggesting that the pathway is the same when they only give one pathway/example... I suppose that is a dangerous assumption to make...

Another question, Passage 1 in BS was confusing me... I think I understand it better now that I am reviewing it... for some reason I thought that all the controls were also receiving pericytes... why do you think that in A-C that the controls had different growth rates? All the controls in A-C were just ECs, right?

 

[MedGrl@2022]

negative and minus sense are the same thing right? If a virus has negative/minus sense RNA it carries its own RNA-dependent RNA polymerases right? Our RNA polymerases are not capable of converting negative sense into plus sense mRNA, right?

 

[Albein]

Michaelis menten formula and the graphs associated: yay or nay? I think the only chapters worth going over TBR bio book 2 are 6, the result of glycolysis, caa and etc and some of the genetics in last 2 chapters.

 

[WSHRocks]

awesome! sometimes I try to think that AAMC is suggesting that the pathway is the same when they only give one pathway/example... I suppose that is a dangerous assumption to make...

Another question, Passage 1 in BS was confusing me... I think I understand it better now that I am reviewing it... for some reason I thought that all the controls were also receiving pericytes... why do you think that in A-C that the controls had different growth rates? All the controls in A-C were just ECs, right?

Controls reflect varation in the data. I can't say I know why the data show such variation, because it's not stated, but there could be many reasons. The passage isn't specific enough about the experiment to see if there were other conditions (you could look at the source if you wish). The most important thing here, of course, is that there is a difference between the appropriate control and the experimental/variable container, and that each experimental container can only be compared against its own control.

 

[WSHRocks]

Michaelis menten formula and the graphs associated: yay or nay? I think the only chapters worth going over TBR bio book 2 are 6, the result of glycolysis, caa and etc and some of the genetics in last 2 chapters.

I doubt we'll need to know the formula; it'll likely be provided. As for the graphs, I think you should just know the shape of the plot, the meaning of the intercepts for the Lineweaver-Burke plot (and be able to extrapolate how the line might changed based on different inhibitors), and how the different inhibitors affect Km and Vmax.

 

[MedGrl@2022]

Controls reflect varation in the data. I can't say I know why the data show such variation, because it's not stated, but there could be many reasons. The passage isn't specific enough about the experiment to see if there were other conditions (you could look at the source if you wish). The most important thing here, of course, is that there is a difference between the appropriate control and the experimental/variable container, and that each experimental container can only be compared against its own control.

I forgot these things were taken from real sources and studies...

I have a question about Passage VI the ebola passage..

So figure 1 is showing the introduction of the genes in different mutant mice... the first is a wildtype, the second is a knock out for CatB and the third is a knock out for both CatB and CatL. The researchers introduced genes into these mice either none, bacterial, CatB, CatL, or both CatL and CatB. What is bacterial? Aren't all the cells exposed to VSV-EGP?

 

[WSHRocks]

I forgot these things were taken from real sources and studies...

I have a question about Passage VI the ebola passage..

So figure 1 is showing the introduction of the genes in different mutant mice... the first is a wildtype, the second is a knock out for CatB and the third is a knock out for both CatB and CatL. The researchers introduced genes into these mice either none, bacterial, CatB, CatL, or both CatL and CatB. What is bacterial? Aren't all the cells exposed to VSV-EGP?

They're simply showing transduction of genes into the mutant mouse strains, and the "bacterial" is a control to show that it's not transduction that is causing the differences when CatB or CatL is added instead. This is necessary to differentiate a non-transduced cell (none) from a transduced cell (bacterial/CatB/CatF). "Bacterial" just means that they transduced a random bacterial gene. These kinds of controls are common and very important for 100% viable interpretation of the data.

 

[MedGrl@2022]

They're simply showing transduction of genes into the mutant mouse strains, and the "bacterial" is a control to show that it's not transduction that is causing the differences when CatB or CatL is added instead. This is necessary to differentiate a non-transduced cell (none) from a transduced cell (bacterial/CatB/CatF). "Bacterial" just means that they transduced a random bacterial gene. These kinds of controls are common and very important for 100% viable interpretation of the data.

WSHRocks... you are amazing... How do you know these things so well? I bet your scoring 15s in the sciences if not close... are you currently an undergrad or something?

 

[Back 5]

Lol, having such a tough time getting motivated to study. I've been staring at my formula sheet for 15 minutes trying to figure out what to cut out and I just feel bleh about the whole thing.

I didn't really use very many formula during aamc#3-#11, but with the test being more calculation based, I feel like I should still memorize one.

Maybe if I read a bit I'll get in the mood.

 

[WSHRocks]

WSHRocks... you are amazing... How do you know these things so well? I bet your scoring 15s in the sciences if not close... are you currently an undergrad or something?

I've learned a lot of this from diverse research experiences - research really helps for BS. I've never gotten a 15 on practice (13-14 mostly), because they always manage to find a hole in my knowledge. My PS is definitely the shakiest (mostly physics), because I never used the material after graduation, except for stoichiometry. I graduated a few years ago, so I'm a working stiff now (and I've been given a rather light work schedule this week).

 

[Postictal Raiden]

all you have to know is generalizations

innate - non specific stuff that kills foreign pathogens aka macrophages and non specific cytokines.

cell mediated- T cell immunity (cd4 helpers cd8 killer)

Humoral - plasma cell/b cell antibody response.

MHC II shows up on plasma cells and MHC I is usually on cells that are infected or contain pathogen particles (neutrophils, macrophages).

I can expand a little bit on what Gandalf said:

The simplified model for cell-mediated immunity is that you have two major types of T cells: helper and cytotoxic T-cells. Scientists use the protein markers CD4 (helper) and CD8 (cytotoxic) to identify them, as these proteins are a key part of their interaction with MHCs. MHCI interacts with CD8 co-receptor, the T-cell receptor of cytotoxic T-cells, and the antigenic protein, while MHCII interacts with CD4, TCR of helper T-cells, and the antigenic protein. I remember this as MHCI, where "I" marks the primary function of the immune system (kill off the bug), and MHCII "II" as the secondary function of enhancing the attack through help.

In viral infections, for example, cytotoxic T-cells release granules containing perforin and granzyme B, which induce apoptosis of the virus-infected cell. Helper T-cells can activate B cells to send out antibodies against viral proteins that they recognize in their CD4-TCR-antigen complex. B cells then become plasma cells, which produce vast amounts of antibody specific for the antigen. These antibodies are then recognized by the complement system, and that is all gobbled up then by macrophages.

I will also just add that it's good to know that there is at least one further major type of T cell, the regulatory T cell (Treg), which acts to inhibit/tone down the response of lymphocytes (T, B cells) to antigen. Tregs are thought to prevent auto-immune responses and to prevent organ rejection for very well-matched MHC donor/recipients (suppression by Tregs is definitely not strong enough for a partial/full allogeneic mismatch).

I think this is sufficient for the MCAT, but let me know if you have any more questions about it.

Thank you guys

 

[MedGrl@2022]

Thank you guys

Watch the Khana Lectures of Immunology... they are great! I think they will tell you everything that you need to know. I HIGHLY recommend them... I think I will rewatch them today too

 

[Albein]

Took a verbal exam (14) and noticed concentration wasn't there. I tried refocusing it, finished it but didnt do too great (7). I really hope I can pull a miracle tomorrow. Maybe it's just concentration because there isn't a pattern to the questions I miss.

 

[Albein]

Watch the Khana Lectures of Immunology... they are great! I think they will tell you everything that you need to know. I HIGHLY recommend them... I think I will rewatch them today too

IMO, it would be wiser to look over reproduction and maybe kidney function than immunology. Immunology didnt seem to be stressed too heavily in any of the exams.

 

[Postictal Raiden]

What passage do you guys speculate to be on the PS tomorrow?

From the trend I observed in the FL's and the real test I had last year, I'm almost confident we will have one thermochemistry passage. Aside from that, I also noticed that the mcat loves waves, so you can count on having one of those passages too. I also speculate that the test will have an acid-base passage, a solution passage, and an electrochemistry passage. In regards to physics, I truly hope they include one about projectile motion or free fall (wishful thinking) and one about force and friction (another wishful thoughts).

Although I think I'm prepared for whatever is being thrown at me, I would really dislike to have passages about electromagnetism, torque, rotational inertia, electron shells and orbitals, and complex optic passage (the ones that combine lenses and mirrors).

 

[Postictal Raiden]

IMO, it would be wiser to look over reproduction and maybe kidney function than immunology. Immunology didnt seem to be stressed too heavily in any of the exams.

Although I truly hope you are right, I learned that an immunology passage was present on one of the tests administered this year.

 

[Albein]

Although I truly hope you are right, I learned that an immunology passage was present on one of the tests administered this year.

In that case, I stand corrected. It just always seemed to me there was a passage on kidney and filtration or blood pressure and something related to reproduction. My ideal BS section would be something with endocrinology, maybe heart, one or two of those Ebola like passages because they're pretty simple once you understand the gist of it and organic chemistry only based on experiments like tlc. I can dream can't i? Oh and naturally a ps section with no physics 😀

Edit: I decided I won't ask the proctor if I'm allowed to write on the sheet during the tutorial. I'm just going to assume I can and hope she doesn't say anything. If she does, I'll tell her I was allowed to during my first take and/or AAMC said it was okay

 

[Status Sciaticus]

What passage do you guys speculate to be on the PS tomorrow?

From the trend I observed in the FL's and the real test I had last year, I'm almost confident we will have one thermochemistry passage. Aside from that, I also noticed that the mcat loves waves, so you can count on having one of those passages too. I also speculate that the test will have an acid-base passage, a solution passage, and an electrochemistry passage. In regards to physics, I truly hope they include one about projectile motion or free fall (wishful thinking) and one about force and friction (another wishful thoughts).

Although I think I'm prepared for whatever is being thrown at me, I would really dislike to have passages about electromagnetism, torque, rotational inertia, electron shells and orbitals, and complex optic passage (the ones that combine lenses and mirrors).

waves, redox, circular motion, fluids, combustion, kinematic/projectiles.


finished the PS.
49/56.

28/28 on chem

21/28 on physics 🙁

comes out to a 12, but i hope these tests questions are representative of the test tomorrow.

 

[Albein]

What passage do you guys speculate to be on the PS tomorrow?

From the trend I observed in the FL's and the real test I had last year, I'm almost confident we will have one thermochemistry passage. Aside from that, I also noticed that the mcat loves waves, so you can count on having one of those passages too. I also speculate that the test will have an acid-base passage, a solution passage, and an electrochemistry passage. In regards to physics, I truly hope they include one about projectile motion or free fall (wishful thinking) and one about force and friction (another wishful thoughts).

Although I think I'm prepared for whatever is being thrown at me, I would really dislike to have passages about electromagnetism, torque, rotational inertia, electron shells and orbitals, and complex optic passage (the ones that combine lenses and mirrors).

Waves, redox, acid base maybe, I think something similar to the haber process mixed with thermochemistry and stoichiometry, maybe a discrete or two with lens (hope it's only a discrete), maybe some kinematic passage with work and or momentum combined.

 

[Status Sciaticus]

anyone remember which protein was responsible for the ameboid movement?

it was either microfilaments or microtubules.

edited with the answer.

 

[Albein]

No sense in going over the operons right?

 

[Albein]

All right ladies and gents, I think I'm done. I'm trying to review but instead stressing out over minor details (IMO). I'm going to try and stay off from sdn so as not to rattle myself. Good luck to you all tomorrow. Stay focused, deep breaths if you feel anxious, and rock this test.

 

[thing]

For hydrostatic pressure of the fluid, it will be top of the fluid to the bottom of the fluid, so 1/4 in your example.

Got it, thanks!


Also here's an ACID-BASE question. I bet we'll see something similar to this so could someone help me out lol. What are the implications of a small Ka on adding a strong base? For example, when you have 50 mL of 0.1 M NH4NO3 with a Ka of 1.9 * 10^-10, does this mean that you reach equivalence point quicker in a titration with NaOH than say a titration of 50 mL of 0.1 M HClO with a Ka of 2.5 * 10^-8 with NaOH? Or is it just that at equivalence, the pH of the titration with the lower Ka acid will be higher?


And tell me if this is right. For a titration between a weak acid and a strong base, the half-way point (in my example...25mL of NaOH) would be the point at which there is equal weak acid/conjugate base and this is where pH=pKa. Then the equivalence point is 50mL, and this is where it exists solely as conjugate base? With a pH in the basic region? Helpppp

 

[MedGrl@2022]

Gah!!! I feel like ANYTHING could be on this test tomorrow!!!! I pray that we all get 45s and never have to retake it! 🙂

 

[Moxess]

Gah!!! I feel like ANYTHING could be on this test tomorrow!!!! I pray that we all get 45s and never have to retake it! 🙂

This is very likely to happen

 

[Technorino]

IMO, it would be wiser to look over reproduction and maybe kidney function than immunology. Immunology didnt seem to be stressed too heavily in any of the exams.

🙄 Oh you'll learn soon enough that the things on the AAMC practice exams are only a tiny bit of the questions you'll see tomorrow. 😉

 

[MedGrl@2022]

Got it, thanks!


Also here's an ACID-BASE question. I bet we'll see something similar to this so could someone help me out lol. What are the implications of a small Ka on adding a strong base? For example, when you have 50 mL of 0.1 M NH4NO3 with a Ka of 1.9 * 10^-10, does this mean that you reach equivalence point quicker in a titration with NaOH than say a titration of 50 mL of 0.1 M HClO with a Ka of 2.5 * 10^-8 with NaOH? Or is it just that at equivalence, the pH of the titration with the lower Ka acid will be higher?

pH=pKa + log((cong base)/(Cong acid))... I don't know if you can make an accurate prediction about time but you can make one about the pH

 

[MedGrl@2022]

Got it, thanks!


Also here's an ACID-BASE question. I bet we'll see something similar to this so could someone help me out lol. What are the implications of a small Ka on adding a strong base? For example, when you have 50 mL of 0.1 M NH4NO3 with a Ka of 1.9 * 10^-10, does this mean that you reach equivalence point quicker in a titration with NaOH than say a titration of 50 mL of 0.1 M HClO with a Ka of 2.5 * 10^-8 with NaOH? Or is it just that at equivalence, the pH of the titration with the lower Ka acid will be higher?

pH=pKa + log((cong base)/(Cong acid))... I don't know if you can make an accurate prediction about time but you can make one about the pH

sorry I messed up 1/2 equivalence point with equivalence point

 

[MedGrl@2022]

Got it, thanks!


Also here's an ACID-BASE question. I bet we'll see something similar to this so could someone help me out lol. What are the implications of a small Ka on adding a strong base? For example, when you have 50 mL of 0.1 M NH4NO3 with a Ka of 1.9 * 10^-10, does this mean that you reach equivalence point quicker in a titration with NaOH than say a titration of 50 mL of 0.1 M HClO with a Ka of 2.5 * 10^-8 with NaOH? Or is it just that at equivalence, the pH of the titration with the lower Ka acid will be higher?

I think yes to your second question... you seem to be on the right path... just to be sure I hope someone else chimes in

 

[HotHamH2O]

Lol, having such a tough time getting motivated to study. I've been staring at my formula sheet for 15 minutes trying to figure out what to cut out and I just feel bleh about the whole thing.

I didn't really use very many formula during aamc#3-#11, but with the test being more calculation based, I feel like I should still memorize one.

Maybe if I read a bit I'll get in the mood.

If you are feeling burnt today, you should just stop. You don't want to feel that way come test time in the morning. I was feeling this way today and I just put it all away and went to the park with my son. I'm done. I want to wake up excited to test tomorrow.

 

[MedGrl@2022]

If you are feeling burnt today, you should just stop. You don't want to feel that way come test time in the morning. I was feeling this way today and I just put it all away and went to the park with my son. I'm done. I want to wake up excited to test tomorrow.

I guess most of us are non-trads here. 🙂 Any undergrads in this forum? Just curious...

 

[HotHamH2O]

🙄 Oh you'll learn soon enough that the things on the AAMC practice exams are only a tiny bit of the questions you'll see tomorrow. 😉

based on what recent test takers are reporting those practice tests are outdated and are a waste of money. Wish I could have my $200+ back.

 

[GemelloMD]

I'm calling it. Time to rest and digest a little before the exam. GL y'all. I'm betting we'll all see each other sometime around noon tomorrow.

 

[Status Sciaticus]

based on what recent test takers are reporting those practice tests are outdated and are a waste of money. Wish I could have my $200+ back.

how did you end up doing on the PS guidebook?

also, does anyone have links to videos that gives a good understanding on how to read/interpret NMR spectra? Khan's vids are just about what NMR is rather than the peaks, splits, integration that we actually need to know for the MCAT

 

[osprey099]

I guess most of us are non-trads here. 🙂 Any undergrads in this forum? Just curious...

I'm a junior in college. Also, I'm 20 years old. I was pretty surprised when several of you guys mentioned you were married/had kids/etc.

 

[Back 5]

If you are feeling burnt today, you should just stop. You don't want to feel that way come test time in the morning. I was feeling this way today and I just put it all away and went to the park with my son. I'm done. I want to wake up excited to test tomorrow.

I'll feel fresh tomorrow. The last puzzle piece is memorizing my formula sheet.

 

[osprey099]

I have a question:

If a study indicates that a certain protein (lets call it aamc1) does not observe changed in total levels nor in localization of the protein following a certain condition (nutrient stress, for instance), does that mean that aamc1 activity is controlled at a posttranscriptional level and why? I can't seem to understand why aamc1 wouldn't be controlled at the posttranslational level instead cause we are observing protein levels and not mRNA levels..

 

[Technorino]

I'm about to do TBR's Molecular Cell Biology Diagnostic Set and then review that and go over the questions in the AAMC "R" exams because there was a passage in one of them that was eeeeerrily similar to what I had seen on the real thing.

Then it's on to writing a formula sheet.

What's a non-trad btw? I see it everywhere but never know what it is.

 

[Back 5]

how did you end up doing on the PS guidebook?

also, does anyone have links to videos that gives a good understanding on how to read/interpret NMR spectra? Khan's vids are just about what NMR is rather than the peaks, splits, integration that we actually need to know for the MCAT

You only need to memorize a couple. We were only asked about the alcohol band, nitrile and carbonyl bands on our practice tests.

3500-3000, 2100, 1750 are the values that stick out in my head as important.

 

[HotHamH2O]

how did you end up doing on the PS guidebook?

also, does anyone have links to videos that gives a good understanding on how to read/interpret NMR spectra? Khan's vids are just about what NMR is rather than the peaks, splits, integration that we actually need to know for the MCAT

i scored equivalent to a 10...i found some of the questions very difficult. the intensity question was just silly. Questions were either very easy or way out of left field and I was oblivious. I did much better on the BS section.

 

[osprey099]

What's a non-trad btw? I see it everywhere but never know what it is.

Someone who is not the usual go straight to med school or take 1-2 gap years then go to med school type.

 

[Status Sciaticus]

You only need to memorize a couple. We were only asked about the alcohol band, nitrile and carbonyl bands on our practice tests.

3500-3000, 2100, 1750 are the values that stick out in my head as important.

youre talking about IR spectroscopy.

Im asking about NMR spectroscopy.

 

[Status Sciaticus]

i scored equivalent to a 10...i found some of the questions very difficult. the intensity question was just silly. Questions were either very easy or way out of left field and I was oblivious. I did much better on the BS section.

maybe you wouldve scored higher if you played a few rounds of team deathmatch on COD😀

but a 10 on each section is good.

 

[HotHamH2O]

I'm about to do TBR's Molecular Cell Biology Diagnostic Set and then review that and go over the questions in the AAMC "R" exams because there was a passage in one of them that was eeeeerrily similar to what I had seen on the real thing.

Then it's on to writing a formula sheet.

What's a non-trad btw? I see it everywhere but never know what it is.

well a traditional applicant is someone applying in their early twenties, bio major, junior or senior undergraduate. so a nontrad would be something that isnt that.

for example, I'm a 26 year old, married, two kids, paramedic in the ER.

 

[Back 5]

youre talking about IR spectroscopy.

Im asking about NMR spectroscopy.

You're right...sorry about that.

For NMR, we were only ever asked about # of peaks. I am not bothering to memorize any of the shifts.

 

[HotHamH2O]

youre talking about IR spectroscopy.

Im asking about NMR spectroscopy.

i would know that an aldehyde is in the 11 region...besides that just know what makes a proton appear more downfield and what makes a proton appear upfield

 

[Technorino]

the last post always goes unread.