cysteine.......

[ChamaDoc]

Some texts list cystein as nonpolar, and others as polar...
What should I regard it as for the MCAT?

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[boaz]

Some texts list cystein as nonpolar, and others as polar...
What should I regard it as for the MCAT?

Polar.

Which texts list it as nonpolar?

 

[ChamaDoc]

ExamKracker's Biology

 

[ChamaDoc]

Sorry, I got confused. It lists it as Polar. Thanks anyway 😀

 

[boaz]

Pop quiz: Natural amino acids--are they R or S?

 

[RogueUnicorn]

sssssssss

 

[boaz]

One exception. 😛

edit: actually two exceptions

 

[RogueUnicorn]

hm really? obviously Gly is achiral... Pro still has a center.. hmm.. interesting...

 

[boaz]

Cysteine: it's the only R group that has a higher priority than the CO2.

But it is still L; it has the same effect on the polarimeter.

 

[ChamaDoc]

Nice.

 

[whiteshadodw]

cysteine is also a titratable group, the side chain has a pKa of ~8.

 

[JmanDO]

What about selenocysteine? Pyrrolysine?