Biochemistry

Question 1

Name the 4 main pancreatic islet cells?

Answer 1

Beta cells
Alpha cells
Gamma cells
PP cells

Question 2

What do beta cells produce?

Answer 2

insulin

Question 3

What do alpha cells produce?

Answer 3

glucagon

Question 4

What do gamma cells produce?

Answer 4

somatostatin

Question 5

What do PP cells produce?

Answer 5

pancreatic polypeptide

Question 6

Describe insulin synthesis?

Answer 6

Synthesised in the ER of beta cells as a larger single chain preprohormone called PREPROINSULIN, it is then cleaved to insulin

Question 7

What is the biochemical make up of insulin?

Answer 7

two polypeptide chains linked by a disulfide bond

there is a byproduct of cleavage - connective C peptide - that has no known function

Question 8

What is the precursor of insulin?

Answer 8

Preproinsulin

Question 9

What is the fastest acting form of insulin?

Answer 9

lispro

- 15 mins from eating

Question 10

What is the longest acting form of insulin?

Answer 10

glargine

Question 11

How does glucose enter Beta cells?

Answer 11

GLUT2 transporter

Question 12

What is glucose phosphorylated by?

Answer 12

glucokinase

Question 13

What does increased glucose metabolism result in?

Answer 13

increased ATP concentration

Question 14

What does high levels of ATP inhibit?

Answer 14

K channels (KATP)

Question 15

What does the inhibition of KATP channels result in for the cell?

Answer 15

depolarisation of the cell

Question 16

What level does glucose need to reach for beta cells to release insulin?

Answer 16

5 mM

Question 17

Describe the two pools of insulin in the body?

Answer 17

one readily releasable pool

one reserved pool

Question 18

What two proteins make up KATP channels?

Answer 18

Kir6 subunit

SUR1 subunit

Question 19

What kind of structure is the KATP channel?

Answer 19

octomeric structure

Question 20

What does a Kir 6.2 mutation cause?

Answer 20

neonatal diabetes

Question 21

What does a Kir 6.2 or SUR1 mutation cause?

Answer 21

congenital hyperinsulinism

Question 22

What is the treatment for congenital hyperinsulinism?

Answer 22

diazonxide

Question 23

What is Kir6?

Answer 23

inwards rectifier subunit

Question 24

What is SUR1?

Answer 24

regulatory subunit

Question 25

What opens the SUR1 channel?

Answer 25

ADP-Mg binding

Question 26

What are the biological things that insulin increases?

Answer 26

amino acid uptake in muscle cells
DNA synthesis
protein synthesis
growth synthesis
glucose uptake in muscle and adipose tissue
lipogenesis in adipose tissue
glycogen synthesis in liver and muscle

Question 27

What are the biological things that insulin decreases?

Answer 27

lipogenesis and gluconeogenesis in the liver

Question 28

What does insulin regulate?

Answer 28

gene expression