6) Lipids & lipoproteins

Question 1

4 lipid functions

Answer 1

• Main source of energy and energy storage
• Converted to hormones or hormone precursors
• Serve as structural and functional components of cell membranes
• Provide insulation for nerve conduction and heat retention

Question 2

5 lipid classes

Answer 2

• Sterol derivatives
• Fatty acids
• Glycerol esters
• Sphingosine derivatives
• Terpenes

Question 3

4 sterol derivatives

Answer 3

• Cholesterol and cholesteryl esters
• Steroid hormones
• Bile acids
• Vitamin D

Question 4

3 size classifications of FAs

Answer 4

Short chain (2-4 C atoms)
Medium chain (6-10 C atoms)
Long chain (12-26 C atoms)

Question 5

terpenes

Answer 5

Vitamin A
Vitamin E
Vitamin K

Question 6

Contains 27 carbon atoms and four fused rings (A, B, C, and D) called the perhydrocyclopentanophenanthrene nucleus.

Answer 6

cholesterol

Question 7

3 main functions of cholesterol

Answer 7

• Structural component of cell membranes
• Precursor of bile acids
• Precursor of Vitamin D and steroid hormones

Question 8

2 forms of cholesterol

Answer 8

exogenous
endogenous

Question 9

Cholesterol is solubilized by the formation of mixed ——-

Answer 9

micelles

Question 10

If the amount of cholesterol ….. then a supersaturated state can occur that results in the formation of gallstones

Answer 10

exceeds the capacity of solubilizing agents

Question 11

FA nomenclature

Answer 11

methyl end = omega end
number for double bond position

Question 12

Derivatives of fatty acids comprising 20 C atoms, including a five-carbon cyclopentane ring

Answer 12

prostaglandins

Question 13

4 functions of prostaglandins

Answer 13

• Contraction and relaxation of smooth muscle
• Dilation and constriction of blood vessels
• Control of blood pressure
• Modulation of inflammation

Question 14

comprise 95% of fat stored in tissue

Answer 14

TGs

Question 15

lecithins

Answer 15

phospholipids

Question 16

Important component of the myelin sheath

Answer 16

sphingomyelin

Question 17

5 components of a lipoprotein

Answer 17

• An outer layer of proteins
• Apolipoproteins
• Polar lipids (phospholipids)
• Unesterified cholesterol
• An inner core of neutral lipids (phospholipids and esterified cholesterol).

Question 18

These are receptor sites or the “address tags” to tell the lipoprotein where to go in the body

Answer 18

apolipoproteins

Question 19

Form the major proteins in HDL and in chylomicrons

Answer 19

Apo-A

Question 20

This is the major protein for LDL and VLDL. This binds LDL to LDL receptors.

Answer 20

Apo-B

Question 21

This lipoprotein helps in metabolism of triglyceride rich lipoproteins

Answer 21

Apo-C

Question 22

This lipoprotein may function as a transfer protein to assist in the movement of cholesterol and triglycerides between LDL and HDL.

Answer 22

Apo-D

Question 23

Important in recognition and catabolism of chylomicrons and remnant IDL.

Answer 23

Apo-E

Question 24

4 pathways of lipoprotein metabolism

Answer 24

Lipid absorption
Exogenous
Endogenous
Reverse cholesterol

Question 25

Triglycerides: 84% Apolipoproteins: 1–2% Cholesterol: 7% Phospholipids: 6%

Answer 25

chylomicrons

Question 26

Triglycerides: 44–60% Cholesterol: 16–22% Apolipoproteins: 2–8% Phospholipids: 18%

Answer 26

VLDL

Question 27

Triglycerides: 25% Cholesterol: 38% Apolipoproteins: 11% Phospholipids: 26%

Answer 27

IDL

Question 28

Triglycerides: 11% Cholesterol: 62% Apolipoproteins: 20% Phospholipids: 23%

Answer 28

LDL

Question 29

Triglycerides: 3% Cholesterol: 19% Apolipoproteins: 50% Phospholipids: 25–30%

Answer 29

HDL

Question 30

short vs long chain FA transportation

Answer 30

Short-chains are carried by albumin to the liver Long-chains are packaged into chylomicrons

Question 31

Composed of the metabolism of **chylomicrons** Responsible for transporting dietary or exogenous fat, mostly triglycerides, from the intestines to the liver and peripheral cells

Answer 31

exogenous pathway

Question 32

chylomicron plasma appearance

Answer 32

turbid creamy layer after ultracentrifuge or sitting at RT

Question 33

chylomicron Apo

Answer 33

Apo A Apo B-48 Apo C-II Apo E

Question 34

Involves the metabolism of very-low-density lipoproteins (VLDL) to intermediate density lipoproteins (IDL) to low-density lipoproteins (LDL)

Answer 34

endogenous pathway

Question 35

VLDL plasma appearance

Answer 35

turbid no creamy layer after ultracentrifugation

Question 36

VLDL Apo

Answer 36

Apo B-100 Apo C-II Apo E

Question 37

Can be elevated in patients with type III hyperlipoproteinemia, a rare inborn error of metabolism

Answer 37

IDL

Question 38

IDL Apo

Answer 38

Apo B-100 Apo E

Question 39

IDL function

Answer 39

Transports triglycerides and cholesterol to the liver from peripheral tissues.

Question 40

LDL function

Answer 40

Major transporter of cholesterol in plasma to peripheral tissues

Question 41

LDL Apo

Answer 41

Apo B-100

Question 42

HDL function

Answer 42

reverse cholesterol transport Cholesterol scavenger that removes cholesterol from tissues and carries it to the liver for disposal

Question 43

HDL Apo

Answer 43

Apo A-I Apo C-II Apo E

Question 44

Independent, causal risk factor for atherosclerosis Highly heritable

Answer 44

Lipoprotein (a)

Question 45

LipoProtein Lipase (LPL) Deficiency

Answer 45

I. Familial Hyperchylomicronemia

Question 46

LDL Receptor Mutations (Deficiency) ApoB-100 Mutations

Answer 46

IIa. Familial Hypercholesterolemia

Question 47

LDL Receptor Mutations Overproduction of VLDL and ApoB-100

Answer 47

IIb. Familial Combined Hyperlipidemia.

Question 48

ApoE Deficiency (Abnormal IDL metabolism)

Answer 48

III. Familial dys-beta-lipoproteinemia

Question 49

Overproduction of VLDL

Answer 49

IV. Familial Hypertriglyceridemia

Question 50

Abnormal VLDL & chylomicron metabolism

Answer 50

V. Familial mixed Hypertriglyceridemia

Question 51

Has been associated with hyperthyroidism and hepatocellular disease Malnutrition, starvation, and eating disorders (anorexia, bulimia) abetalipoproteinemia

Answer 51

hypocholesterolemia

Question 52

Associated with acute pancreatitis as both a precipitant and an epiphenomenon

Answer 52

hypertriglyceridemia

Question 53

A very rare condition that affects fat and vitamin absorption by the intestines and liver, leading to very low LDL-cholesterol and malnutrition.

Answer 53

abetalipoproteinemia

Question 54

enzymes used in cholesterol methodology

Answer 54

cholesterol esterase cholesterol oxidase

Question 55

Classic method and can separate/fractionate all lipoproteins

Answer 55

Analytical ultracentrifugation

Question 56

Heparin-manganese-chloride (method of choice) Dextran sulfate-magnesium chloride Sodium phosphotungstate Mg2+

Answer 56

used in selective precipitation HDL left in solution

Question 57

Uses an antibody to Apo B-100 to bind LDL and VLDL.

Answer 57

Homogenous enzyme assays (block non-HDL)

Question 58

Friedewald formula for indirect LDL

Answer 58

LDL = total cholesterol - (HDL + TG/5) | TG/5 = VLDL

Question 59

cannot use indirect LDL method if...

Answer 59

TG level is over 400 mg/dL High amount of chylomicrons Dysbetalipoproteinemia

Question 60

TG methodologies use enzyme...

Answer 60

lipase

Question 61

Group of interrelated metabolic risk factors that appear to directly promote the development of atherosclerotic cardiovascular disease

Answer 61

metabolic syndrome

Question 62

criteria for metabolic syndrome

Answer 62

**Must have 3:** - Increased waist circumference **(>40 in men; >35 in women)** - Elevated triglycerides **(>150 mg/dL**; or on TG meds) - Low HDL-C **(<40 mg/dL men; <50 mg/dL women**; or on HDL meds) - Elevated blood pressure (**>130/85**; or on HTN meds) - Elevated fasting glucose (**>100 mg/dL**; or on DM meds)