Amino Acids

Question 1

How many naturally occurring amino acids are there

Answer 1

20

Question 2

Do amino acids carry a charge at their neutral pH

Answer 2

Yes, at pH7 the carboxyl group is negatively charged and the amine group is positively charged

Question 3

Are amino acids chiral?

Answer 3

Yes, all amino acids except glycine are chiral and have non-superimposable mirror images

Question 4

Which isomer do amino acids in proteins exclusively form

Answer 4

Amino acids in proteins are exclusively in the L-isomer form.
(As opposed to natural sugars in carbohydrates that take the D-isomer form).

Question 5

What are the 4 categories of amino acid classification

Answer 5

Non-polar
Polar and uncharged
Polar and positively charged (acidic)
Polar and negatively charged (basic)

Question 6

What are the aliphatic amino acids

Answer 6

Alanine, glycine, valine, leucine, isoleucine and proline

Question 7

What are the aromatic amino acids

Answer 7

Phynlalanine, tryptophan and tyrosine

Question 8

What are the sulphur containing amino acids

Answer 8

Cystine And Methionine

Question 9

What is a zwitterion

Answer 9

A molecule with both a positive and negative charge

Question 10

What is the isoelectric point of an amino acids

Answer 10

The pH at which the net charge of the amino acid is 0

Question 11

Which are more thermodynamically stable, amino acids or proteins

Answer 11

Amino acids are more stable, however the breakdown of proteins into amino acids has a high activation energy so the reaction won’t take place despite being favourable