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Question 534
Biochemistry → General
Classification
Question
SSBAQuestion Header
A newly synthesised protein is destined for a peroxisome rather than a lysosome or the cell membrane. At which site is its synthesis most consistent with the described ribosomal organisation?
Question Stem
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Options
A
Golgi trans face
B
Smooth endoplasmic reticulum
C
Nucleolus
D
Free ribosome
E
Rough endoplasmic reticulum-bound ribosome
Explanation
Free ribosomes synthesise proteins including those destined for peroxisomes and mitochondria, as well as haemoglobin. Ribosomes attached to rough endoplasmic reticulum synthesise proteins including lysosomal and membrane proteins.
Option Validity
A) The Golgi apparatus processes and packages material but is not the ribosomal site of protein synthesis described.
B) Smooth endoplasmic reticulum is associated with functions such as lipid and steroid synthesis rather than ribosomal protein synthesis.
C) The nucleolus is a nuclear structure rather than the site of synthesis of the peroxisomal protein described.
E) Rough endoplasmic reticulum-bound ribosomes synthesise proteins including lysosomal and membrane proteins, whereas peroxisomal proteins are associated with free ribosomes.
Further Reading
Richa Saxena. Textbook for MRCOG-1: Basic Sciences in Obstetrics & Gynaecology. Biochemistry and Nutrition — Biochemistry — Ribosomes. Printed page 127.