Quiz | Amino Acids, Peptides and Proteins

1

Which of the following statements about amino acids is incorrect?

Amino acids are both basic and acidic

Amino acids have only two chemical functions: a carboxylic acid group and an amino group

α-amino acids are the most common amino acids in nature

α-carbon has generally a S configuration

2

In a basic aqueous solution (pH > 13), the dominant form of an amino acid is:

NH3+-CHR-COOH

NH3+-CHR-COO-

NH2-CHR-COO-

NH2-CHR-COOH

3

What is the isoelectric pH of glycine (pKaCOOH = 2.3; pKaNH2 = 9.7)?

2.3

6.0

9.7

12.0

4

At pH < pI, the population of amino acids in solution will have:

A net positive charge

A net negative charge

No charged groups

No net charge

5

Which of the following structures describes the overall 3D folding of a polypeptide?

Primary structure

Secondary structure

Tertiary structure

Quaternary structure

6

Which of the following statements about the polypeptides is incorrect?

The amide bonds of polypeptides are called peptide bonds

Polypeptides are hydrolyzed in acidic condition to form amino acids

Polypeptides are characterized by their sequence of amino acid from the carboxy end (left) to the amino end (right)

Polypeptides synthesis is the coupling between an amino-protected amino acid and a carboxy-protected amino acid