Question

Ricin, a protein from castor beans, causes toxicity in humans by

• A. Depurinating the 23S ribosomal RNA
• B. Inactivating the 60S ribosomal subunit
• C. Inhibiting the elongation factor eEF2
• D. Intercalating DNA

Hint:

Ricin acts by inhibiting protein synthesis through inactivation of the 60S ribosomal subunit.

Answer 1

The Correct Option is B

Step 1: Understanding Ricin Toxicity.
Ricin is a potent toxin that inhibits protein synthesis by inactivating the 60S ribosomal subunit, preventing translation.
Step 2: Analyzing the Options.
- (A) Incorrect. Ricin does not depurinate the ribosomal RNA; it affects ribosome function.
- (B) Correct. Ricin inactivates the 60S ribosomal subunit, thereby halting protein synthesis.
- (C) Incorrect. While eEF2 is involved in translation, ricin does not inhibit it directly.
- (D) Incorrect. Ricin does not intercalate DNA; it affects ribosomes and translation.
Step 3: Conclusion.
Thus, the correct answer is (B).