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Question 544
Biochemistry → General
Classification
Question
SSBAQuestion Header
Which combination most accurately describes the ribosome?
Question Stem
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Options
A
Membrane-bound; predominantly protein; single subunit
B
Non-membrane-bound; approximately 65% RNA and 35% protein; two subunits
C
Double-membrane-bound; contains DNA; two subunits
D
Single-membrane-bound; predominantly RNA; contains acid hydrolases
E
Non-membrane-bound; composed of tubulin; cylindrical
Explanation
Ribosomes lack a limiting membrane, measure approximately 15 nm, consist of about 65% RNA and 35% protein, and contain two subunits.
Option Validity
A) Ribosomes are not membrane-bound and are predominantly RNA rather than protein.
C) Ribosomes do not possess a double membrane or their own DNA.
D) Acid hydrolases within a limiting membrane characterise lysosomes rather than ribosomes.
E) Tubulin-containing cylindrical structures describe centrioles or microtubular structures, not ribosomes.
Further Reading
Saxena - MRCOG-1 Basic Sciences - Biochemistry, printed p.127.