Session 7 - The insuliny/pancreas bit Flashcards Preview

Semester 1 - Metabolism > Session 7 - The insuliny/pancreas bit > Flashcards

Flashcards in Session 7 - The insuliny/pancreas bit Deck (3)
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1
Q

Give four ultrastructural features of B cells which make it specialised for insulin secretion

A

Extensive rough endoplasmic reticulu
a well defined golgi apparatus
many mitochondria
a well defined system of microtubles and microfilaments.

2
Q

Give insulin synthesis up to disulphide bond formation

A

Synthesised as pre-proinsulin on ribosomes associated with rough endoplasmic reticulum

Pre-part is a signal peptide which ensures newly synthesised protein enters cisternal space of the endoplasmic reticulum. Then removed.

Remaining proinuslin folds to ensure correct alignment of the cysteine residues and the correct disulphide bonds

3
Q

Give synthesis and secretoon of insulin from disulphide bond formation

A

Proinsulin transported to golgi apparatus from ER and packaged into storage vesicles.

Proteolysis in stroage vesicles removes a connecting peptide from near the middle of the chain.

This breaks single chain into two chains held by disulphide bridge - mature insulin.

Storage vesicle contain insulin and C-peptide in equimolar amounts.

Entire contents realeased during secretion. Measurement of C-peptide useful marker of insulin secretion