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Endocrine > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

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

A

Beta cells

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2
Q

What do beta cells produce?

A

insulin

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3
Q

What are the other cells present within the pancreatic islets?

A

alpha
gamma
PP

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4
Q

What do PP cells secrete?

A

pancreatic polypeptide

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5
Q

What do gamma cells secrete?

A

somatostatin

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6
Q

Where exactly in beta cells is insulin produced?

A

In the ribosomes of the RER

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7
Q

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

A

Preproinsulin- a type of preprohormone

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8
Q

What molecular chains does insulin contain?

A

2 polypeptide chains, joined by a disulphide bond

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9
Q

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

A

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

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10
Q

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

A

GLUT2

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11
Q

What does glucosekinase do?

A

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

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12
Q

In what process is the most ATP formed?

A

Oxidative phosphorylation during glucose metabolism

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13
Q

What effect does ATP have on the K+ channel?

A

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

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14
Q

What mineral change does cell membrane depolarisation have?

A

Influx of Ca++

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15
Q

How is insulin released within the cell?

A

Ca++ binds with secretory vesicles and releases insulin

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16
Q

True or False.

Insulin release is triphasic.

A

False.

It is biphasic.

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17
Q

What is the first phase of insulin release?

A

Release of readily releasable pool (RRP) of insulin granules

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18
Q

What is the second phase of insulin release?

A

Granules which undergo preparatory reactions are released.

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19
Q

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

A

Sulphonylureas

20
Q

What 2 proteins make up K+ channel?

A

Kir6.1

SUR1

21
Q

What does the drug diazoxide do?

A

Inhibits insulin secretion so good for hypoglycaemia

22
Q

What does MODY stand for?

A

Maturity-onset diabetes of the young.

23
Q

What is the pathogenesis of MODY?

A

Monogenic diabetes with genetic defect in B cell function.

24
Q

What is the relevance of HNF transcription factors?

A

A genetic abnormality in HNF causes MODY

25
Q

What is the pathology of type 1 diabetes?

A

Loss of beta cells so no insulin secretion.

26
Q

What is the pathology of type 2 diabetes?

A

Reduced insulin sensitivity or defect in the insulin composition

27
Q

What is insulin’s receptor?

A

Tyrosine kinase receptor

28
Q

What does phosphorylation require?

A

ATP –> ADP + Pi

29
Q

What is the insulin receptor made up of?

A

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

30
Q

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

A

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

31
Q

What do IRS activate?

A

PI3K and then PKB..

32
Q

What role does PKB play in glycogen synthesis?

A

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

33
Q

Where do ketone bodies come from?

A

Acetyl-CoA from beta oxidation.

Formed in liver mitochondria.

34
Q

What are ketones used for?

A

Energy metabolism for heart and renal cortex.

35
Q

How are ketones used for energy metabolism?

A

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

36
Q

What are examples of ketones?

A

Acetone
Acetoacetic acid
beta-hydroxybutate

37
Q

What is consumed in gluconeogenesis?

A

Oxaloacetate

38
Q

What happens when ketone bodies accumulate in the blood?

A

Acidosis occurs.

39
Q

DKA is classic in DM1 or DM2?

A

DM1

40
Q

Which three amino acids can be phosphorylated?

A

Serine
Threonine
Tyrosine

41
Q

Which enzyme converts glucose to sorbitol?

A

Aldose reductase

42
Q

How does sorbitol cause diabetic complications?

A

causes osmotic damage e.g.gathering in the lens

43
Q

True or False

Inhaled steroids can cause osteoporosis

A

False

Only oral

44
Q

True or False

A direct effect of steroids is an increase in calcium absorption

A

False.

Decreases Ca absorption

45
Q

True or False

An indirect effect of steroids is inhibition of gonadal steroid production

A

True.

Also adrenal

Endocrine (20 decks)

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