insulin and diabetes

Question 1

structure of insulin

Answer 1

insulin a-chain has 21 amino acids, b-chain has 30. chains are connected by two disulphide bonds.

Question 2

insulin biosynthesis in B-cells

Answer 2

nucleus - transcription of gene -> preproinuslin mRNA
ER - mRNA -> preproinsulin, cleaved to proinsulin
golgi - proindulin packaged into secretory granules
proinsulin then converted to insulin and C peptide.

Question 3

structure of insulin hexamer

Answer 3

6 insulin moelcules surrounding a zionc ion, which they interact with via their b-chain histidine residues

Question 4

type 1 diabetes

Answer 4

autoimmune destruction of islet b-cells, progressive disorder

Question 5

type 2 diabetes

Answer 5

insulin resistance in peripheral tissues and b-cell dysfunction - impaired insulin secretion

Question 6

maturity onset diabetes of the young (MOBY)

Answer 6

caused by single gene mutations, causes b-cell defects, insufficient insulin secretion or synthesis. not common (1-2%)