What do we have to know about amino acids??

[unsung]

Uworld just quizzed me with a structure of an amino acid and a Q on pKa.

Wtf.

Can anyone summarize what we should know about this topic? I don't really want to memorize a bunch of structures/pKas...

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[ArcGurren]

For what it's worth, I never once had a question requiring me to know the pKa or structure of any amino acid. I always found that a slightly bizarre UW question.

However you should know what is in FA - which ones are basic, which ones are neutral, which ones are acidic. They can easily ask a question about a transmembrane protein and say "which amino acid comprises most of the phospholipid-encased part?" and you'd have to understand that neutral = hydrophilic = can be integral within the membrane.

 

[dude1344]

UWSA2 spoiler - highlight to read.

I got owned on UWSA2 with a question that asked what amino acid would be found within hydrophobic membrane. I narrowed it down btwn glycine and histidine but picked histidine because we all know it has no charge at body pH.

But UW said it's positive and the answer is glycine...

 

[dude1344]

What about the Glucogenic, glucogenic/ketogenic, ketogenic AA's... I haven't memorized them yet. Has anyone actually seen those on any exams, practice or real?

Anyone got a mnemonic for them? lol.

 

[deleted387928]

For what it's worth, I never once had a question requiring me to know the pKa or structure of any amino acid. I always found that a slightly bizarre UW question.

However you should know what is in FA - which ones are basic, which ones are neutral, which ones are acidic. They can easily ask a question about a transmembrane protein and say "which amino acid comprises most of the phospholipid-encased part?" and you'd have to understand that neutral = hydrophilic = can be integral within the membrane.

do you mean neutral=hydrophobic?

 

[deleted387928]

What about the Glucogenic, glucogenic/ketogenic, ketogenic AA's... I haven't memorized them yet. Has anyone actually seen those on any exams, practice or real?

Anyone got a mnemonic for them? lol.

Use GAVLIMP for the hydrophobic amino acids: glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine

 

[iA-MD2013]

What about the Glucogenic, glucogenic/ketogenic, ketogenic AA's... I haven't memorized them yet. Has anyone actually seen those on any exams, practice or real?

Anyone got a mnemonic for them? lol.

Leucine and lysine = only ketogenic...I've seen that a few times. I haven't found a reason to memorize which ones are glucogenic only vs glucogenic + keotgenic but I'm sure some stupid practice question will require that valuable knowledge.

 

[bobsagat]

What about the Glucogenic, glucogenic/ketogenic, ketogenic AA's... I haven't memorized them yet. Has anyone actually seen those on any exams, practice or real?

Anyone got a mnemonic for them? lol.

These are kind of stupid... but hey, you asked.

Essential AAs of each type:
Glucogenic: his, val, met, arg. I think of two ladies arguing over how much sugar to add to a recipe. HIS wife MET VALerie ARGuing over sugar.

Ketogenic: lys, leu. DKA KiLLs.

Both: phe, ile, trp, thr. PHoebe and I'Ll BOTH TRIP THRICE. (I dunno, maybe both of you are real klutzes? Kind of reaching on this one but it works for me.)

As for pKAs and all that crap, I really doubt anything like that will come up, but I do second the idea that being able to put the AAs into groups based on their R groups is potentially valuable. I know there was an NBME question that functionally asked about which R group could/couldn't be phosphorylated, in which case you'd have had to know which ones have a hydroxyl in their R group.

 

[ArcGurren]

do you mean neutral=hydrophobic?

Yes