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Biochem 2 Exam 2 > Lipid Digestion > Flashcards

Lipid Digestion Flashcards

0
Q

What are the two interconnected cycles of lipoprotein metabolism centered on the liver?

A

Endogenous and exogenous

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1
Q

What are lipoproteins and what do they do?

A

Non-covalent complexes of lipids and proteins; carry lipids through the bloodstream

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2
Q

What is purpose of particle density? What are the defining characteristics?

A

It is used to classify lipoproteins.

Difference in composition, structure, and function.

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3
Q

Protein constituents of lipoproteins have what 2 roles?

A

structural and functional

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4
Q

What is the shape of lipoproteins and what structures are on the surface?

A

Spherical with proteins, cholesterol, and phospholipids on the surface

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5
Q

What makes up the inside of the sphere?

A

Non-polar lipids

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6
Q

What are the major classifications of lipoproteins, and how are they determined?

A

Determined based upon density

Chylomicrons, VLDL, ILDL, LDL, HDL

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7
Q

True/False: The lipoproteins have a MONO-layer of mainly amphipathic lipids

A

True

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8
Q

Which Apoproteins are embedded in the monolayer?

A

Apo B100 and Apo B48

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9
Q

What carries free fatty acids?

A

Albumin

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10
Q

Which lipoprotein has the smallest density? Why?

A

Chylomicrons; they are filled with TAGs

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11
Q

Which lipoproteins are the most dense? Why?

A

HDLs; they are full of esterfied cholesterol

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12
Q

Which lipoproteins are the largest in diameter? Which are the smallest?

A

Chylomicrons are the largest; HDL is the smallest

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13
Q

Which lipoprotein has the highest percent of cholesterol and cholesterol ester?

A

LDL

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14
Q

What is the purpose of bile salts?

A

They emulsify dietary fats and increase surface area of the lipid to speed up digestion.

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15
Q

What do intestinal enzymes breakdown?

A

Dietary TAG, cholesterol esters, and phospholipids

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16
Q

What are the 3 main intestinal enzymes for digestion of lipids and what is the 1 helper enzyme?

A

Pancreatic lipase, Cholesterol esterase, and Phospholipase

Helper: Colipase

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17
Q

What is the purpose of pancreatic lipase?

A

Cleaves ester bonds in dietary TAG

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18
Q

What is the purpose of Colipase?

A

Helps pancreatic lipase attach to micelles.

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19
Q

What is the purpose of Cholesterol esterase?

A

Hydrolyzes cholesterol esters

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20
Q

What is the purpose of Phospholipases?

A

Breaks down phospholipids

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21
Q

Where are TAGs and cholesterols transferred?

A

They are transferred across the intestinal mucosa

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22
Q

What happens to TAGs and cholesterol once inside the enterocyte?

A

TAG: are reformed
Cholesterol: esterfied with fatty acids

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23
Q

What is required to bring TAGs into the chylomicrons?

A

Microsomal Triglycerides Transferase

24
Q

Once formed, where are chylomicrons transferred and where to they go from there?

A

Lymphatic circulation then it goes to the blood stream (L Subclavian Vein)

25
Q

What enzyme in the blood stream is activated by Apo CII in the Chylomicrons and VLDs?

A

Lipoprotein lipase

26
Q

What does lipoprotein lipase do to the Chylomicrons?

A

They release fatty acids from the Chylomicrons

27
Q

What happens to the released fatty acids from the Chylomicrons?

A

They enter cells and are repackaged into VLDLs.

28
Q

What happens to Chylomicron remnants?

A

They are degraded by the liver.

29
Q

True/False: Chylomicrons release cholesterol to the tissues

A

FALSE!!! They DO NOT release cholesterol to tissues.

30
Q

Chylomicrons are carriers of lipids from what area?

A

The GI

31
Q

Where and when are chylomicrons synthesized?

A

intestinal epithelium; after a meal

32
Q

Of what are the chylomicrons the principal carriers?

A

dietary lipids and fat-soluable vitamins (D,A,K,E)

33
Q

What is the purpose of chylomicrons?

A

Deliver lipids to tissues.

34
Q

Where would you NOT find chylomicrons?

A

normal fasting plasma

35
Q

What apoproteins are in chylomicrons?

A

Apo B-48 (added upon formation)

A-I, C-II, E (added after entering the blood from HDL)

36
Q

Where and from what are VLDLs made?

A

Liver; biosynthesis of FA and chylomicron remnants.

37
Q

What is the main purpose of VLDLs?

A

They are the main carrier of endogenously synthesized TAGs to tissues

38
Q

Which apoproteins are in VLDLs?

A

Apo B-100 (Added upon synthesis)

C-II, and E (Added from HDL in the blood stream)

39
Q

Where and from what are LDLs formed? What is the intermediate structure?

A

They are formed from VLDLs in the circulation; ILDL

40
Q

What is the purpose of LDLs?

A

Transport cholesterol to the tissues

41
Q

Which Apoprotein is contained in LDL? How does that differ from ILDL?

A

ILDL has Apo B-100, C-II, and E, but returns the Apo C-II and Apo E to HDL. It is then LDL and only contains Apo B-100

42
Q

HDL is the smallest lipoprotein particle but most abundant, what is its function?

A

It takes cholesterol from the tissues back to the liver for excretion. It also distributes cholesterol to other lipoproteins (reverse cholesterol transport).

43
Q

Which apoproteins does HDL contain?

A

Apo A-I and A-II

44
Q

Where is HDL made?

A

Liver and sm. intestines

45
Q

What is the purpose of Apoprotein A-1?

A

Activates LCAT and binds HDL receptor

HelLcat esterfies

46
Q

What is the function of Apoprotein B-48?

A

It is involved in the formation of chylomicrons (embedded within the monolayer)

47
Q

What is the function of Apoprotein B-100?

A

It binds LDL receptor (docking element)

48
Q

What is the function of Apoprotein C-II? And which lipoproteins does this effect?

A

It activates lipoprotein lipase (LPL); chylomicrons and VLDLs

49
Q

What is the function of Apoprotein E?

A

Recognition of the LDL receptor (docking protein to remove the remnants of chylomicrons)

50
Q

What protein is involved in reverse cholesterol transport (aside from HDL)?

A

Cholesterol ester transfer protein (CETP) - it mediates the exchange of cholesterol from HDL to VLDL, ILDL, and LDL

51
Q

What is the function of lipoprotein lipase?

A

It delipidates VLDL and the chylomicrons at the capillary surface

52
Q

What is LCAT?

A

It is a peripheral protein that is made in the liver and secreted in the blood.

53
Q

What can happen to LDL in the presence of ROS?

A

It can not get rid of fat and produces fatty streaks in the coronary vessels, leading to plaque build-up.

54
Q

What is the shape of HDL prior to esterification by LCAT?

A

It begins as a disc, but as cholesterol esters are added, it becomes more dense and spherical.

55
Q

What type of receptor is an LDL receptor?

A

glycoprotein

56
Q

What is ACAT (aceyl-CoA cholesterol acyl transferase)?

A

It transfers a FA from fatty acyl CoA to cholesterol producing a cholesterol ester, which is then stored.

57
Q

What is another activator of lipoprotein lipase?

A

Insulin

58
Q

Once the chylomicron is deplipidated, which peripheral apoprotein is returned to HDL? And what is the function of the remaining peripheral apoprotein?

A

Apo C-II is returned to HDL. Apo E remains to bind to receptors on the liver for endocytosis.

Biochem 2 Exam 2 (7 decks)

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