Midterm 1 - Lecture 6, 7

Question 1

What does the omega end of a FA look like?

Answer 1

CH3

Question 2

What does the alpha end of a FA look like?

Answer 2

CH2-COOH

Question 3

Structural difference between SFA and Monounsaturated FA?

Answer 3

1 C=C somewhere in the monounsaturated FA

Question 4

Structural difference between Polyunsaturated and Monounsaturated FA?

Answer 4

Poly has more than 1 C=C and must be separated by 1 -C-

Question 5

Nomenclature of FAs

Answer 5

C16:0 refers to 16 carbons, 0 C=C
C18:1 ω-9 refers to 18 carbons, 1 C=C 9 carbons away from omega end

Question 6

Degradation of FAs via Beta-oxidation

Answer 6

Fatty acyl CoA transporter (requires carnitine) brings FAs into Mitochondria for breakdown into Ac-CoA->TCA cycle; Also requires FAD+ and NAD+

Question 7

FA synthesis

Answer 7

• occurs in cytosol; adds 2 carbons using Malonyl-CoA
• Involves acyl-carrier protein (ACP), NADPH, enzymes ACC & FAS;
• Initial product: palmitate (C16:0)
• Further products made by elongases & desaturases

Question 8

What is the limitation of human desaturases?

Answer 8

Work only up to α-9; cannot create ω-3 or ω-6 FAs from Palmitic acid (Therefore they are essential FAs)

Question 9

Synthesis of Long Chain PUFA for Omega-6 FA metabolism

Answer 9

Linoleic (ω-6) (18:2) -> Gamma linolenic acid (18:3) -> Arachidonic acid (20:4)

Question 10

Synthesis of Long Chain PUFA for Omega-3 FA metabolism

Answer 10

Alpha-linolenic acid (ω-3) (18:3) -> EPA eicosapentaenoic acid (20:5) -> DHA

Question 11

Eicosanoids from ω-6 vs. ω-3 FAs

Answer 11

Arachidonic -> Pro-inflammatory eicosanoids; Increase blood clotting
EPA -> anti-inflammatory eicosanoids; Decrease blood clotting; reduce heart attack risk

Question 12

Fxns of Eicosanoids

Answer 12

Signaling molecules involved in inflammation & pain

prostaglandins) and blood clotting (thromboxane

Question 13

How does aspirin affect blood clotting?

Answer 13

Aspirin inhibits COX-1, which ultimately inhibits vasoconstriction and inhibits increase in platelet aggregation

Question 14

Fxns and characteristics of DHA

Answer 14

• Important for brain, eye and heart function.
• Protect cells in heart and lower lethal arrhythmia.
• Decreases risk of dementia
• slows loss of mental function
• affects volume of the brain (the lower DHA levels in blood, the smaller & more impaired the brain)

Question 15

Lipid digestion

Answer 15

• They are water insoluble, and thus difficult to hydrolyze
• Great energy source
• Small intestine: major site for lipid digestion and FA absorption
• Lipids in SI -> cholecystokinin (CCK) -> release of bile acids and lecithin from gallbladder and lipases from pancreas -> fat absorbed transferred to lymph

Question 16

Fxn of Lecithin and bile acids

Answer 16

emulsify fats

Question 17

Characteristics of Lecithin

Answer 17

A phospholipid; 1 glycerol branched with 2 FAs, 1 phosphate choline

Question 18

Fxns of cholesterol

Answer 18

• Essential component of cell membranes
• Produced by the liver (20%) & rest of body (80%)
• Found only in animal products
• Precursor to estrogen, testosterone and vitamin D
• Precursor to bile acids
*NOT ESSENTIAL

Question 19

How does too much dietary cholesterol (e.g. >1 egg) affect a healthy person’s risk of CHD?

Answer 19

little change in CHD risk

Question 20

How does too much dietary cholesterol (e.g. >1 egg) affect a diabetic’s or obese’s risk of CHD?

Answer 20

great harm to arteries and thus noticeable change in CHD risk; but in general, Sat or Trans fat play larger roles in risk

Question 21

Fxn of Chylomicrons

Answer 21

Chylomicrons transport dietary lipids & cholesterol from

SI -> liver and tissues

Question 22

What is a remnant and where is it processed?

Answer 22

FA-depleted chylomicron, processed in liver.

Question 23

VLDL - Very low-density lipoprotein

Answer 23

-made by liver, rich in lipids, main supplier of liver FA to
tissues where lipoprotein lipase removes lipids.
-As lipids are removed, density increases -> LDL and VLDL remnant.

Question 24

LDL - Low-density lipoprotein

Answer 24

Biggest component is cholesterol

Question 25

In healthy people, LDL is removed by:

Answer 25

the liver via LDL receptors

Question 26

In diseased people, LDL is removed by:

Answer 26

White blood scavenger cells, which can form plaques in arteries
-May be from too much animal or trans fats, or disease

Question 27

HDL - High-density lipoprotein

Answer 27

Scavenge cholesterol -> return to liver

Question 28

Atherosclerosis (plaque in artery) risks

Answer 28

Risk increased by smoking, diabetes, hypertension, inflammation, obesity, diets high in animal fat.

Question 29

How does higher Total Cholesterol related to CHD risk?

Answer 29

Increased risk of CHD

Question 30

2 types of medications for reducing CVD risk

Answer 30

Statins

Baby aspirin

Question 31

Effects of statins

Answer 31

-inhibitor of cholesterol synthesis
-lowers LDL levels & reduces inflammation.
-Side effects: can damage mitochondrial function & ->
muscle pain & damage, memory loss, diabetes

Question 32

Effects of baby aspirin

Answer 32

-reduces inflammation.
-Side effects: damages GI track (~10% of chronic users
get ulcers)

Question 33

Define Lipolysis

Answer 33

Mobilization of stored fats in adipose tissue; rate depends on presence of hormones and cytokines

Question 34

Anabolism of stored FA via Feeding

Answer 34

Feeding -> Insulin -> inhibits HSL (a lipase) ->Fewer free FAs released from adipose tissue -> Fewer free FAs used for energy

Question 35

Catabolism of stored FA between meals

Answer 35

Between meals -> Glucagon -> activates HSL -> more free FAs released from adipose tissue -> More free FAs used for energy

Question 36

Android fat in men

Answer 36

in upper body, promoted by testosterone and alcohol
and more mobile (easily shed), but includes visceral (deeper, around organs in abdomen) fat which has more disease associations (Diabetes T2, CVD, hypertension)

Question 37

Fat in women

Answer 37

more lower body fat, promoted by estrogen/progesterone and less mobile

Question 38

Types of body fat

Answer 38

• subcutaneous, for insulation

- visceral

Question 39

Why is Partial hydrogenation harmful?

Answer 39

FAs become trans FAs, which greatly increase risk of CVD