Question

Approximate numbers of proteins present in 40 S subunit of mammalian ribosomes are

• A. 25
• B. 35
• C. 45
• D. 55

Hint:

To remember:
- Eukaryotic 40S Subunit \(\approx\) 1 RNA (18S) + 33-35 Proteins.
- Prokaryotic 30S Subunit \(\approx\) 1 RNA (16S) + 21 Proteins.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Eukaryotic ribosomes (80S) are complex ribonucleoprotein structures composed of two major functional subunits: the small 40S subunit and the large 60S subunit.

Step 2: Detailed Explanation:
Let us analyze the composition of the mammalian 80S ribosome:
1. 60S Subunit (Large): Contains 3 ribosomal RNA molecules (28S, 5.8S, and 5S rRNAs) complexed with approximately 46 to 49 proteins.
2. 40S Subunit (Small): Contains a single 18S ribosomal RNA molecule complexed with approximately 33 to 35 proteins.
Thus, the approximate number of proteins in the small eukaryotic ribosomal subunit is 35.

Step 3: Final Answer:
The correct option is 2, which corresponds to 35.