Amino Acids

Question 1

Why are amino acids said to be amphoteric?

Answer 1

They have both a basic amino (-NH2) group and an acidic carboxylic acid (-COOH) group.
They can act as both acids and bases.

Question 2

What type of amino acids are in proteins?

Answer 2

2-aminocarboxylic acids.
The amine group and carboxylic acid group are bonded to the same C atom.

Question 3

General formula of amino acids found in proteins

Answer 3

RCH(NH2)COOH

Question 4

What type of reactions can amino acids undergo?

Answer 4

Amino acids will undergo most reactions of amines and carboxylic acids including acid-base reactions of:
- Amines with acids
- Carboxylic acids with bases

Question 5

What is the R group on an amino acid?

Answer 5

An organic side chain
(except in glycine where R is hydrogen)

Question 6

Why are amino acids considered chiral molecules?

Answer 6

Amino acids (except glycine) are chiral molecules because they have 4 different groups around a central carbon atom.

Question 7

What are alpha amino acids?

Answer 7

Alpha amino acids are where NH2 is attached to the C adjacent to COOH.
They have the general formula RCH(NH2)COOH.

Question 8

How do amino acids react with alkalis?

Answer 8

Amino acids react with alkalis to form salts.
Alkalis react with the COOH group in amino acids to form a conjugate base - RCH(NH2)COO- which combines with a positive ion to form a salt.

Question 9

How do amino acids react with acids?

Answer 9

Amino acids react with acids to form salts.
Acids react with the amino group NH2 to form a conjugate acid.

Question 10

How do amino acids react with alcohols?

Answer 10

Amino acids react with alcohols to form esters.
Alcohols react with the COOH group in the amino acids to form an ester + water.
This requires a stong acid catalyst e.g. H2SO4.