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Flashcards in Biochemistry Deck (45)
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1

Within the pancreatic islets, which cells are in the majority?

Beta cells

2

What do beta cells produce?

insulin

3

What are the other cells present within the pancreatic islets?

alpha
gamma
PP

4

What do PP cells secrete?

pancreatic polypeptide

5

What do gamma cells secrete?

somatostatin

6

Where exactly in beta cells is insulin produced?

In the ribosomes of the RER

7

What does the RER actually synthesise before it forms into insulin?

Preproinsulin- a type of preprohormone

8

What molecular chains does insulin contain?

2 polypeptide chains, joined by a disulphide bond

9

Cows and pigs were used for insulin in the past, why are they not used now?

Sometimes induce antibodies against the insulin, over a prolonged period of time.

10

Which glucose transporter is on the cell membrane of beta cells ?

GLUT2

11

What does glucosekinase do?

Converts glucose to glucose-6-phosphate where it can be used in metabolism

12

In what process is the most ATP formed?

Oxidative phosphorylation during glucose metabolism

13

What effect does ATP have on the K+ channel?

It inhibits K+ channel, which leads to depolarisation of cell membrane

14

What mineral change does cell membrane depolarisation have?

Influx of Ca++

15

How is insulin released within the cell?

Ca++ binds with secretory vesicles and releases insulin

16

True or False.
Insulin release is triphasic.

False.
It is biphasic.

17

What is the first phase of insulin release?

Release of readily releasable pool (RRP) of insulin granules

18

What is the second phase of insulin release?

Granules which undergo preparatory reactions are released.

19

Which class of drugs mechanism of action inhibits K+ channels?

Sulphonylureas

20

What 2 proteins make up K+ channel?

Kir6.1
SUR1

21

What does the drug diazoxide do?

Inhibits insulin secretion so good for hypoglycaemia

22

What does MODY stand for?

Maturity-onset diabetes of the young.

23

What is the pathogenesis of MODY?

Monogenic diabetes with genetic defect in B cell function.

24

What is the relevance of HNF transcription factors?

A genetic abnormality in HNF causes MODY

25

What is the pathology of type 1 diabetes?

Loss of beta cells so no insulin secretion.

26

What is the pathology of type 2 diabetes?

Reduced insulin sensitivity or defect in the insulin composition

27

What is insulin's receptor?

Tyrosine kinase receptor

28

What does phosphorylation require?

ATP --> ADP + Pi

29

What is the insulin receptor made up of?

2 extracellular alpha subunits which bind insulin
2 transmembrane beta subunits.
Bound by a disulfide bond

30

What happens when the alpha subunits of the insulin receptor are activated?

The beta subunits undergo self phosphorylation and therefore the insulin receptor substrates (IRS) are phosphorylated