Structure and Properties of Amino Acids - Medical Science

Q1:

The sulphur containing side chain of cysteine is

A ampiphillic, highly reactive and capable of reacting with another cysteine

B hydrophillc, highly reactive and capable of reacting with another cysteine

C hydrophobic, highly reactive and capable of reacting with another cysteine

D none of the above

ANS:C - hydrophobic, highly reactive and capable of reacting with another cysteine

The correct answer will be B that because the following charged:

Arginine - Arg - R.
Lysine - Lys - K.
Aspartic acid - Asp - D.
Glutamic acid - Glu - E.

Polar (may participate in hydrogen bonds)hydophilic:

Glutamine - Gln - Q.
Asparagine - Asn - N.
Histidine - His - H.
Serine - Ser - S.
Threonine - Thr - T.
Tyrosine - Tyr - Y.
Cysteine - Cys - C.
Methionine - Met - M.
Tryptophan - Trp - W.

Hydrophobic (normally buried inside the protein core):

Alanine - Ala - A.
Isoleucine - Ile - I.
Leucine - Leu - L.
Phenylalanine - Phe - F.
Valine - Val - V.
Proline - Pro - P.
Glycine - Gly - G.