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Question 518
Biochemistry → General
Classification
Question
SSBAQuestion Header
A phagocytic cell has internalised particulate material into a membrane-bound compartment. Which subsequent event produces the active organelle responsible for degradation of this material?
Question Stem
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Options
A
Fusion of a primary lysosome with the phagosome to form a secondary lysosome
B
Fusion of a peroxisome with the phagosome
C
Direct conversion of the phagosome into a primary lysosome
D
Fusion of the phagosome with a secretory vesicle from the endoplasmic reticulum
E
Transfer of the phagocytosed material directly into a mitochondrion
Explanation
Primary lysosomes are inactive Golgi-derived vesicles containing hydrolytic enzymes. Fusion of a primary lysosome with a phagosome containing ingested material produces an active secondary lysosome. Its acidic environment activates the hydrolytic enzymes responsible for degradation.
Option Validity
B) Peroxisomes do not form secondary lysosomes.
C) A phagosome does not directly become a primary lysosome; primary lysosomes are Golgi-derived vesicles.
D) Formation of an active secondary lysosome requires fusion with a primary lysosome.
E) Mitochondria do not receive phagocytosed material for lysosomal degradation.
Further Reading
Richa Saxena. Textbook for MRCOG-1: Basic Sciences in Obstetrics & Gynaecology. Biochemistry and Nutrition — Biochemistry — Lysosomes. Printed page 126.