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Biochem block 3 > Lecture 2b-Lipoproteins > Flashcards

Lecture 2b-Lipoproteins Flashcards

1
Q

Where are lipids derived from? and examples

A
  • fatty acids
  • e.g. fats, oils, waxes, steroids and sterols, hormones
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2
Q

What is the function of lipids

A
  • energy source
  • component of cell membranes
  • hormones-cell:cell communication
  • insulation for nerves (sphingomyelins)
  • Protection of and insulation for organs
  • Vit A, D,E,K are lipid soluble
  • Buoyancy
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3
Q

why do lipids present a special challenge?

A

They are hydrophobic

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4
Q

Fatty acids make up….

A

cholesterol and triacylglycerols (Fats, triglycerides)

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5
Q

Cholesterol makes hormone that we need for _____ _____

A

dietary needs

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6
Q

Triacylglycerols are used for?

A

for energy

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7
Q

What transports lipids

A

lipoproteins

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8
Q

What is the composition of a lipoprotein

A
  • inside: core containing triacylglycerols and cholesteryl esters
  • Outside: phospholipids, cholesterols, apolipoproteins (binds lipid to proteins to be transported)
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9
Q

Part two of anatomy of lipoprotein

A

Core: nonpolar lipids
* cholesterol ester
* triglyceride

Outside: amphipathic lipids
* phopholipid
* cholesterol

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10
Q

What does cholesterol do?

A

Prevents it from collapsing

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11
Q

name the lipoproteins from highest to lowest density

A

HDL, LDL,IDL, VLDL, chylomicrons

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12
Q

Which lipoprotein has the most triacylglyerols

A

chylomicron which also has the least cholesterol

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13
Q

Which lipoprotein has the most cholesterol

A

LDL

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14
Q

The more triacylglycerols, what happens to size of lipoprotein

A

it gets bigger

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15
Q

As density increases, the size

A

decreases

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16
Q

what are apoprotiens

A

are on the surface, providing structure and function (binding and enzyme activation

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17
Q

Apo A-I is associated with what lipoprotein and what is the function

A
  • HDL
  • Structural protein for HDL and activator of LCAT
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18
Q

Apo B-100 is associated with what lipoprotein and what is the function

A
  • VLDL, IDL, LDL
  • structural protein for VLDL and LDL and ligand for binding to LDL receptor
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19
Q

Apo B-48 is associated with what lipoprotein and what is the function

A
  • Chylomicrons
  • Structural proteins for chylomicrons
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20
Q

ApoA-1 is unique to what

A

to HDL–> structural and enzyme activator

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21
Q

ApoB is unique to what?

A

to non-HDL particles–> structural and ligand for receptor binding

22
Q

how do we change apolipoproteins B?

A

mRNA editing

23
Q

What happens to the apolipoprotein B in the intestine

A
  • There is cytidine demainase editing complex (active) which changes CAA to UAA (stop codon) so we get 48
24
Q

What happens to the apolipoprotein B in the liver

A

The codon stays as a Gln (CAA) and becomes a apoB100 proteins

25
Q

apoB 48 is expressed in what and involved in what ?

A

Expressed mucosal cells and involved in receptor mediated chylomicron by the liver

26
Q

apoB 100 is expressed in what and involved in what ?

A

expressed in the liver and involved in receptor mediated LDL uptake by the liver

27
Q

explain the process of chylomicrons

A
28
Q

Lipoprotein lipase (LPL) reaction

A
29
Q

lipoprotein lipase present in:

A
  • adipocytes
  • striated mucsles
  • prancreatic islets
  • macrophages
30
Q

What is the fuction of lipoprotein lipase

A

Hydrolysis of TG presents hydrolysis of TG present in chylomicrons and very-low density lipoproteins

31
Q

what is the substrate for LPL reaction

A

triacylglycerol

32
Q

What are the products of the lipoprotein lipase reaction

A

1,2-diacylglycerol and fatty acid

33
Q

explain how VLDL and LDL are interconnected

A
34
Q

What is the subtrate for lipoprotein

A

triglycerol

35
Q

What is the LCAT reaction

A
36
Q

What substrate can be used besides lecitin ?

A

Acyl-coenzyme:cholesterol actltransferases (ACAT)

37
Q

what lipoprotein does reverse cholesterol transport?

A

HDL particles

38
Q

What does HDL do

A
39
Q

What is the function of HDL and LDL

A
  • HDL: reverse cholesterol transport back to the liver for excretion
  • LDL: takes cholesterol to all different organs
40
Q

Explain the interconnecions of CETP (cholesterol ester transfer protein

A
41
Q

Overview of HDL particles-reverse cholesterol transport

A
  • HDL removes cholesterol from tissue and transports it to liver
  • liver disposes cholesterol as bile acids
  • HDL is called “good” cholesterol
42
Q

What happens when cholesterol is taken up via LDL receptors

A
  • LDL is internalized, then lysomoal hydrolysis to relaease cholesterol
  • Once you have enough cholesterol in the cell regulatory actions:
    1. decrease HMG CoA reductase (enzyme that makes cholesterol
    2. increase ACAT or LCAT (makes cholesterol esters
    3. decrease LDL receptors (no more cholesterol taken up
43
Q

Where are chylomicrons synthesis in, secreted into, contains, rich in and function

A
  • Synthesis in: The small intestines in the fed state
  • Secreted into: the lymph vessels, then—> moves into the blood
  • Contains apo B48
  • Rich in:TGs
  • Function: deliver TG’s to body cells to be used as fuel
44
Q

Where are VLDL synthesis in, secreted into, contains, rich in and function

A
  • Synthesis in the liver from excess dietary carbohydrate and protein along with the Chylomicron remnant
  • Secreted into: the bloodstream
  • Rich in: TGs
  • Function: Deliver TGs to body cells
  • Contains apo B100
45
Q

Where are LDL synthesis in, secreted into, results from, rich in and function

A
  • Synthesis in the Liver as VLDL
  • Results from: VLDL once it has lost a lot of its TG’s and
    C–>CE
  • Secreted into: the bloodstream
  • Rich in: Cholesterol
  • Function: Deliver cholesterol to all body cells
46
Q

Where are HDL synthesis in, secreted into, results from, rich in and function

A
  • Synthesis in : the Liver and Small Intestine
  • Secreted into: the bloodstream
  • Function: Pick up cholesterol from body cells and take it back to the liver = “reverse cholesterol transport”
  • Potential to help reverse heart disease
47
Q

What does hyperlipidemia/hyperlipoproteinemia cause

A

Increase risk of atherosclerosis and cardiovascular diseases

48
Q

What is familial hypercholesterolemia

A
  • FH patients have high LDL and plasma cholesterol levels
  • Lack LDL receptors: decrease degradation of LDL
  • Mutations in LDL receptor gene
49
Q

What is are the souces of cholesterol

A

found in aminal food only

50
Q

Where is cholesterol synthesized ?

A

Liver

51
Q

What is the atherosclerosis: LDL hypthesis?

A
  • Elevated levels of LDL cholesterol and apoB100 directly contribute to atherosclerosis
  • Oxygen radicals in endothelial lining of the arteries oxidize LDL and retain them
  • Activated endothelial cells have increased inflammation
  • Macrophages take up LDL and are saturated with cholesterol thus forming foam cells
52
Q

What are the major enzymes of lipoprotein metabolism:

A
  • Lipase (LPL)
  • Lecithin:Cholesterol Acyl Transferase (LCAT)
  • Cholesterol ester transfer Protein (CETP)

Biochem block 3 (6 decks)

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