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Question 566
Biochemistry → General
Classification
Question
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A hydrolytic protein is synthesised normally, but a defect prevents material arriving from the endoplasmic reticulum from entering the cis face of the Golgi apparatus. Which downstream sequence would therefore be most directly disrupted?
Question Stem
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Options
A
Processing and packaging of the enzyme → primary lysosome formation → secondary lysosome formation after fusion with an endosome
B
Beta-oxidation → hydrogen-peroxide detoxification → bile-acid formation
C
Chromatin condensation → spindle formation → chromosome movement
D
Tubulin assembly → ciliary movement → intracytoplasmic transport
E
DNA base pairing → mRNA transmission → microfilament contraction
Explanation
Lysosomal enzymes are synthesised in rough ER and subsequently reach the Golgi apparatus, where they are processed and packaged into small vesicles. These vesicles pinch off as primary lysosomes. Fusion of a primary lysosome with an endosome or phagosome forms the active secondary lysosome. Failure of ER-derived material to enter the Golgi cis face would therefore disrupt this linked pathway.
Option Validity
B) These are peroxisomal metabolic functions and do not depend on the described ER-to-Golgi lysosomal pathway.
C) Chromatin and chromosome movement involve nuclear structures, centrioles and the mitotic spindle rather than lysosomal trafficking.
D) These are microtubule-related functions rather than consequences of failure of Golgi entry.
E) DNA complementary pairing, nuclear transmission of genetic instructions and microfilament contraction are distinct processes and do not represent the described trafficking pathway.
Further Reading
Saxena R. Textbook for MRCOG-1: Basic Sciences in Obstetrics & Gynaecology. Chapter 4 — Endoplasmic Reticulum, Golgi Apparatus and Lysosomes. Printed pages 125–126.