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Biochem > Cholesterol > Flashcards

Cholesterol Flashcards

0
Q

Where does cholesterol synthesis occur?

A

Cytoplasm

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1
Q

RLS of cholesterol synthesis

A

HMG-CoA –> mevalonate

HMG-CoA reductase

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2
Q

MOA of statins

A

Competitive inhibitor of HMG CoA reductase

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3
Q

Effect of insulin and glucagon on cholesterol synthesis

A

Insulin dephosphorylates –> activates

Glucagon phosphorylates –> inactivates

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4
Q

Primary bile acids

A

Cholic acid

Chenodeoxycholic acid

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5
Q

Conjugated primary bile acids become?

A

Conjugation with TAURINE or GLYCINE

Bile acids –> bile salts

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6
Q

Secondary bile acids

A

Deoxycholic acid

Lithocolic acid

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7
Q

Where are bile acids and bile salts absorbed

A

Terminal ileum 95%

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8
Q

MOA of cholestyramine

A

Bile acid sequestrant

Bind bile acids in the gut, preventing their reabsorption, promoting excretion

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9
Q

Lipoprotein with lowest density and largest size

A

ChyLOmicron

Think: malaking LOBO

  • largest size = most lipid
  • lowest density = magaan = least protein
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10
Q

Densest lipoprotein

A

HDL

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11
Q

Apolipoprotein necessary for activation of lipoprotein lipase

A

Apo C-II

II = LL = lipoprotein lipase

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12
Q

Function of lipoprotein lipase

A

Degrades TAGs within the chylomicron

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13
Q

Degradation of TAGs form what products

A

Fatty acids –> stored by adipose or used by muscle

Glycerol –> used by liver

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14
Q

Stimulus for lipoprotein lipase synthesis

A

Insulin - fed state

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15
Q

Where is VLDL produced

A

Liver

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16
Q

Function of VLDL

A

Carry triglycerol from the liver to the peripheral tissues

In the periphery, it will be degraded by lipoprotein lipase also

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17
Q

Who donates Apo C-II and Apo-E?

A

HDL

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18
Q

As the VLDL exists the liver as nascent VLDL, what apoprotein does it carry?

A

Apo B-100

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19
Q

Primary function of LDL

A

Provide cholesterol to peripheral tissues or to return it to the liver

20
Q

What receptors do peripheral tissue recognize?

A

Apo B-100

21
Q

To whom does HDL give Apo C-II and Apo E

A

Chylomicrons

VLDL

22
Q

Function of Apo E

A

Required for receptor mediated endocytosis of IDLs and chylomicron remnants to the liver

23
Q

Cholesterol immediately esterified by — when it is taken up by HDL

A

PCAT or LCAT
phosphatidylcholine: cholesterol acyltransferase
Or lecithin

24
Q

Responsible for reverse cholesterol transport

A

HDL

Cholesterol from peripheral cells –> to HDLs –> to liver for bile acid synthesis or disposal via bile

25
Q

Activates nascent HDL

A

Apo A-I

26
Q

Abetalipoproteinemia - deficiency?

A

Apo B-48 (chylomicrons) and Apo B-100 (VLDL, LDL)

Intestinal malabsorption with accumulation of lipids in intestines and liver

27
Q

Familial lipoprotein lipase - deficiency?

A

Lacks lipoprotein lipase - unable to degrade

High VLDL and chylomicron levels in plasma
Xanthomas and pancreatitis
No increased risk for CAD

28
Q

Familial Hypercholesterolemia - deficiency?

A

LDL receptors
High LDL levels in blood

These receptors are important for uptake by liver in tissues

Xanthomas and xanthelasmas
Increased risk for CAD

29
Q

Activates LCAT to produce cholesterol esters

A

Apo A-1

30
Q

Where are chylomicrons assembled

A

Intestinal mucosal cells (from dietary lipids - primarily triglycerol)

31
Q

Primary component of nascent VLDL

A

Triacylglycerol

32
Q

When peripheral tissues endocytose LDLs, what happens?

A

Contents are degraded in the lysosomes

33
Q

Where are HDLs synthesized

A

Liver and intestines

34
Q

Responsible for esterifying cholesterol from other lipoproteins

A

HDL

Using PCAT/ LCAT

35
Q

After esterifiation of cholesterol via PCAT/ LACT, what happens

A

It is activated by Apo A-1 and delivered to the liver (aka reverse cholesterol transport)

36
Q

Deliver cholesterol to liver for elimination

A

HDL

37
Q

Deliver cholesterol to peripheral tissues

A

LDL

38
Q

Deliver de novo TAG to peripheral tissues

A

VLDL

39
Q

Deliver dietary TAG to peripheral tissues

A

Chylomicrons

40
Q

Lowest TAG content

A

HDL

41
Q

Highest TAG content

A

Chylomicrons

42
Q

Highest cholesterol content

A

LDL

43
Q

Lowest cholesterol content

A

Chylomicrons

44
Q

Role of exogenous chenodeoxycholic acid

A

Increases cholesterol solubility in bile, acting like an emulsifying agent

45
Q

Once glycerol (product of lipoprotein lipase degradation) is produced, what will happen?

A

It is converted to DHAP and enters glycolysis or gluconeogenesis

46
Q

What activates pancreatic lipase

A

Trypsin

Found in intestinal lumen

47
Q

What activates hormone sensitive lipase?

A

Glucagon

During fasting
Found in the liver

48
Q

Highest protein content

A

HDL

‘Heavy’

Biochem (11 decks)

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