Question

Identify the side chain –R present in amino acid lysine.

• A. –C\(_6\)H\(_5\)–
• B. –(CH\(_2\))\(_4\)–NH\(_2\)
• C. –CH\(_2\)OH
• D. –CH(CH\(_3\))\(_2\)

Hint:

Lysine, arginine, and histidine are basic amino acids due to extra –NH\(_2\) groups.

Answer 1

The Correct Option is B

Step 1: Recall the structure of lysine.
Lysine is a basic amino acid with an additional amino group in its side chain.
Step 2: Write the general structure.
\[ \mathrm{NH_2-CH(R)-COOH} \]
Step 3: Identify the side chain of lysine.
The side chain consists of four methylene groups followed by an amino group:
\[ \mathrm{R = -(CH_2)_4-NH_2} \]
Step 4: Conclusion.
The correct side chain present in lysine is option (B).