need to know structure for all AA?

[BeatMCAT]

Do we need to know structures for all 20 AA or is it fine if you know the names and if they re acidic, basic, etc.? Thanks

---

Members don't see this ad.

 

[ThirdEye]

Knowing structures isn't worth your time. Knowing that proline's structure will cause a kink, and that glycine is the smallest is all you need to know (but you don't necessarily need to know these). Know that HAL are your basic ones and you should be golden.

You'll most likely be able to answer any questions on aminos from your passage.

 

[Lexicon0]

Honestly, if you have the time and are willing to put in the effort, I would go ahead and memorize the side-chains of some of the major amino acids. My MCAT went into nitpicky details regarding side-chains and pkas of amino acids and memorizing these details would have been an immense help.

 

[Temperature101]

Knowing structures isn't worth your time. Knowing that proline's structure will cause a kink, and that glycine is the smallest is all you need to know (but you don't necessarily need to know these). Know that HAL are your basic ones and you should be golden.

You'll most likely be able to answer any questions on aminos from your passage.

Also cysteine can form covalent bond with another cysteine, which yield disulfide bond.

 

[BeatMCAT]

ok. thanks a lot guys!

 

[mitchlucker]

Honestly, if you have the time and are willing to put in the effort, I would go ahead and memorize the side-chains of some of the major amino acids. My MCAT went into nitpicky details regarding side-chains and pkas of amino acids and memorizing these details would have been an immense help.

You aren't implying we should memorize pKas are you? That would really piss me off if my test had the individual pKas on it and expected you to know them prior to a passage or something.

 

[BeatMCAT]

You aren't implying we should memorize pKas are you? That would really piss me off if my test had the individual pKas on it and expected you to know them prior to a passage or something.

I def. dont think we need to know the pkas for each side chain. We should def know the pkas for carboxylic acid. around 2-4 and amino group around 9-10. And then understand that if ph>pkA, then it will be deprotonated, and if ph<pKA, it will be protonated.

 

[BerkReviewTeach]

The answer from someone who took the MCAT:

My MCAT went into nitpicky details regarding side-chains and pkas of amino acids and memorizing these details would have been an immense help.

Of everyone who posted in this thread, the one who took the MCAT is the one who believes you are better served knowing the structures and some pKa values. I've taken the MCAT as well and I agree with Lexicon0 that there are some passages where they expected me to know some things cold. They may give you information in the passage (and plenty of it), but if you aren't familiar with the trends and don't know how to extrapolate from that information, you waste a whole lot of time. Sometimes already knowing information that was given in the passage helps because you get through the passage and questions faster.

Why be afraid to know some things? Based on my experience taking the exam, I would be familiar with some garden variety facts when it comes to amino acids. As mentioned, know what proline and cysteine do to protein structures. I'd also add knowing that histidine is active near pH of 7 because its sidechain pKa is around 6. I'd have a general idea which amino acids were polar, which are acidic, and which are basic.

I'd know that tyrosine is used in many biosyntheses of catecol amines. These sort of random facts help in the oddest of ways of certain questions. I for one would not be trying to know as little as possible for the test. I'd rather know a little more than I needed than a little less. Memorizing all 20 structures is overkill, but I do think it's worth knowing everything I mentioned above.

 

[Majik]

I don't think there's that many pKa's to learn.

You have your acidic amino acids:
Glutamic Acid
Aspartic Acid

I believe both have a pKa around 4.

You have your basic amino acids:
Histidine
Lysine
Arginine

Histine has a pKa around 6.
Lysine and Argine are around 11.

You have polar amino acids that have protic amino acids:
Cysteine has a pKa around 8.
Tyrosine has a pKa around around 10.

Knowing these are optional, however it's essential you know that:
-COOH terminal has a pKa around 2
- NH4 terminal has a pKa around 9

Whether you decide to memorize these are entirely up to you.

 

[Lexicon0]

I don't think there's that many pKa's to learn.

You have your acidic amino acids:
Glutamic Acid
Aspartic Acid

I believe both have a pKa around 4.

You have your basic amino acids:
Histidine
Lysine
Arginine

Histine has a pKa around 6.
Lysine and Argine are around 11.

You have polar amino acids that have protic amino acids:
Cysteine has a pKa around 8.
Tyrosine has a pKa around around 10.

Knowing these are optional, however it's essential you know that:
-COOH terminal has a pKa around 2
- NH4 terminal has a pKa around 9

Whether you decide to memorize these are entirely up to you.

This list should be sufficient. It would be even better if you use these pka values study the change in charge with respect to a titration. Here's a useful link of pkas for all the amino acids: http://www.anaspec.com/html/pK_n_pl_Values_of_AminoAcids.html

 

[BeatMCAT]

Thanks all!!!

 

[docntrainin]

Hey guys, it wasn't mentioned here but in the EK 1001 book, one amino acid that comes up a lot and the book says is an MCAT favorite aa fact is that valine is non polar!