Biochemistry

Question 1

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

Answer 1

Beta cells

Question 2

What do beta cells produce?

Answer 2

insulin

Question 3

What are the other cells present within the pancreatic islets?

Answer 3

alpha
gamma
PP

Question 4

What do PP cells secrete?

Answer 4

pancreatic polypeptide

Question 5

What do gamma cells secrete?

Answer 5

somatostatin

Question 6

Where exactly in beta cells is insulin produced?

Answer 6

In the ribosomes of the RER

Question 7

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

Answer 7

Preproinsulin- a type of preprohormone

Question 8

What molecular chains does insulin contain?

Answer 8

2 polypeptide chains, joined by a disulphide bond

Question 9

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

Answer 9

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

Question 10

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

Answer 10

GLUT2

Question 11

What does glucosekinase do?

Answer 11

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

Question 12

In what process is the most ATP formed?

Answer 12

Oxidative phosphorylation during glucose metabolism

Question 13

What effect does ATP have on the K+ channel?

Answer 13

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

Question 14

What mineral change does cell membrane depolarisation have?

Answer 14

Influx of Ca++

Question 15

How is insulin released within the cell?

Answer 15

Ca++ binds with secretory vesicles and releases insulin

Question 16

True or False.

Insulin release is triphasic.

Answer 16

False.

It is biphasic.

Question 17

What is the first phase of insulin release?

Answer 17

Release of readily releasable pool (RRP) of insulin granules

Question 18

What is the second phase of insulin release?

Answer 18

Granules which undergo preparatory reactions are released.

Question 19

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

Answer 19

Sulphonylureas

Question 20

What 2 proteins make up K+ channel?

Answer 20

Kir6.1

SUR1

Question 21

What does the drug diazoxide do?

Answer 21

Inhibits insulin secretion so good for hypoglycaemia

Question 22

What does MODY stand for?

Answer 22

Maturity-onset diabetes of the young.

Question 23

What is the pathogenesis of MODY?

Answer 23

Monogenic diabetes with genetic defect in B cell function.

Question 24

What is the relevance of HNF transcription factors?

Answer 24

A genetic abnormality in HNF causes MODY

Question 25

What is the pathology of type 1 diabetes?

Answer 25

Loss of beta cells so no insulin secretion.

Question 26

What is the pathology of type 2 diabetes?

Answer 26

Reduced insulin sensitivity or defect in the insulin composition

Question 27

What is insulin's receptor?

Answer 27

Tyrosine kinase receptor

Question 28

What does phosphorylation require?

Answer 28

ATP --> ADP + Pi

Question 29

What is the insulin receptor made up of?

Answer 29

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

Question 30

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

Answer 30

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

Question 31

What do IRS activate?

Answer 31

PI3K and then PKB..

Question 32

What role does PKB play in glycogen synthesis?

Answer 32

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

Question 33

Where do ketone bodies come from?

Answer 33

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

Question 34

What are ketones used for?

Answer 34

Energy metabolism for heart and renal cortex.

Question 35

How are ketones used for energy metabolism?

Answer 35

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

Question 36

What are examples of ketones?

Answer 36

Acetone Acetoacetic acid beta-hydroxybutate

Question 37

What is consumed in gluconeogenesis?

Answer 37

Oxaloacetate

Question 38

What happens when ketone bodies accumulate in the blood?

Answer 38

Acidosis occurs.

Question 39

DKA is classic in DM1 or DM2?

Answer 39

DM1

Question 40

Which three amino acids can be phosphorylated?

Answer 40

Serine Threonine Tyrosine

Question 41

Which enzyme converts glucose to sorbitol?

Answer 41

Aldose reductase

Question 42

How does sorbitol cause diabetic complications?

Answer 42

causes osmotic damage e.g.gathering in the lens

Question 43

True or False | Inhaled steroids can cause osteoporosis

Answer 43

False | Only oral

Question 44

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

Answer 44

False. | Decreases Ca absorption

Question 45

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

Answer 45

True. | Also adrenal