Iddo's test 4, questions 9 and 10

luis (candeias@graylab.ac.uk)
Tue, 13 Feb 96 09:42:59 -0600

Hi, all!
I found these questions really tough. I don't want to spoil anybody's fun
so, if you have not tried this test, I advise not to read this any further
until you've tried it.

If I understood the questions, they concern the chirality of the
beta-carbon. I identify the aminoacids as:

a: L-Thr, configuration of the beta carbon = R
b: L-Thr, configuration of the beta carbon = S (L-alo-Thr)

c: L-Ile, configuration of the beta carbon = R
d: L-Ile, configuration of the beta carbon = S

I found some refernces to a being the natural form in proteins and I
assumed that c is also the natural form of Ile. This doesn't seem to be
the right answer, though.
What is the right answer and why?

As to question 10, I think these are the only two aminoacids with
asymmetric beta carbon. However, 2 is not among the choice of answers.

Am I totally wrong ? Is there life in Mars ? Is there life after this
course ?
Luis