From the statements given below choose the correct option :
A. The eukaryotic ribosomes are 80S and

Q: What is NEET?

NEET is a competitive examination conducted in India. This question is from the 2025 NEET Biology paper.

Q: How can I prepare for NEET Biology?

To prepare for NEET Biology, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2025 question covers Cell: The Unit of Life topic.

Q: What is the difficulty level of this question?

This NEET 2025 Biology question has a easy difficulty level and is marked as an important question and is one of the most repeated questions.

Q: Where can I find more NEET previous year questions?

You can find more NEET previous year questions on AspirantMitraa. Browse by subject, topic, year, and difficulty level to practice effectively.

Question

From the statements given below choose the correct option :
A. The eukaryotic ribosomes are 80S and prokaryotic ribosomes are 70S.
B. Each ribosome has two sub-units.
C. The two sub-units of 80S ribosome are 60S and 40S while that of 70S are 50S and 30S.
D. The two sub-units of 80S ribosome are 60S and 20S and that of 70S are 50S and 20S.
E. The two sub-units of 80S are 60S and 30S and that of 70S are 50S and 30S.
(1) B, D, E are true
(2) A, B, C are true
(3) A, B, D are true
(4) A, B, E are true

Accepted Answer

Correct Answer: B — A, B, C are trueStep-by-step Solution:Ribosomes are the molecular machines of protein synthesis. Evaluating each statement:A — TRUE: Eukaryotic ribosomes have a sedimentation coefficient of 80S and prokaryotic ribosomes are 70S. The 'S' unit (Svedberg unit) measures the rate of sedimentation in an ultracentrifuge and is not simply additive — it depends on size, shape, and density. Eukaryotic 80S ribosomes are larger and heavier than prokaryotic 70S ribosomes.B — TRUE: Every ribosome, regardless of type, consists of two unequal subunits — a large subunit and a small subunit. The small subunit decodes the mRNA; the large subunit catalyzes peptide bond formation (via its peptidyl transferase center, which is rRNA-based — a ribozyme).C — TRUE: 80S ribosome subunits: Large = 60S (contains 28S, 5.8S, and 5S rRNA + ~49 proteins), Small = 40S (contains 18S rRNA + ~33 proteins). Note: 60S + 40S = 80S (not additive — Svedberg units are not linear). 70S ribosome subunits: Large = 50S (contains 23S, 5S rRNA + ~31 proteins), Small = 30S (contains 16S rRNA + ~21 proteins).D — FALSE: The small subunit of 80S is 40S (not 20S), and the small subunit of 70S is 30S (not 20S). 20S is not a ribosomal subunit in any organism.E — FALSE: The small subunit of 80S is 40S (not 30S). 80S has a 60S large + 40S small subunit — not 60S + 30S.Extended Explanation:The distinction between 70S and 80S ribosomes is clinically and evolutionarily important: Antibiotics that target 70S ribosomes (prokaryotic) without affecting 80S (eukaryotic) are selectively toxic to bacteria — this is the basis of antibiotic therapy. Examples: Streptomycin, neomycin, kanamycin target 30S subunit; Erythromycin, chloramphenicol, lincomycin target 50S subunit; Tetracyclines block aminoacyl-tRNA binding to 30S subunit. Eukaryotes also have 70S ribosomes in mitochondria and chloroplasts (endosymbiotic origin of these organelles). This is why some antibiotics (like chloramphenicol) can have mitochondrial side effects in eukaryotes at high doses. Ribosomes were discovered by George Palade (Nobel Prize 1974) and are also called 'Palade granules.'Key Concepts: Ribosome structure, sedimentation coefficients (S values), 80S eukaryotic (60S+40S), 70S prokaryotic (50S+30S), antibiotic targets, rRNA components.

Master NEET with Our Test Series

More Questions from Cell: The Unit of Life

Frequently Asked Questions

Master NEET with Our Test Series

More Questions from Cell: The Unit of Life

Frequently Asked Questions