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Flashcards in Biochemistry Deck (45)
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

31

What do IRS activate?

PI3K and then PKB..

32

What role does PKB play in glycogen synthesis?

PKB causes translocation of GLUT4 to cell membrane so glucose can enter the cell.

33

Where do ketone bodies come from?

Acetyl-CoA from beta oxidation.
Formed in liver mitochondria.

34

What are ketones used for?

Energy metabolism for heart and renal cortex.

35

How are ketones used for energy metabolism?

ketones are converted back to acetyl-CoA which enters TCA cycle.

36

What are examples of ketones?

Acetone
Acetoacetic acid
beta-hydroxybutate

37

What is consumed in gluconeogenesis?

Oxaloacetate

38

What happens when ketone bodies accumulate in the blood?

Acidosis occurs.

39

DKA is classic in DM1 or DM2?

DM1

40

Which three amino acids can be phosphorylated?

Serine
Threonine
Tyrosine

41

Which enzyme converts glucose to sorbitol?

Aldose reductase

42

How does sorbitol cause diabetic complications?

causes osmotic damage e.g.gathering in the lens

43

True or False
Inhaled steroids can cause osteoporosis

False
Only oral

44

True or False
A direct effect of steroids is an increase in calcium absorption

False.
Decreases Ca absorption

45

True or False
An indirect effect of steroids is inhibition of gonadal steroid production

True.
Also adrenal