lecture 8

Question 1

fatty acids

Answer 1

hydrocarbon chin with carboxyl group, can have a double bond that introduces a kink

Question 2

most abundant dietary lipids, triglycerides

Answer 2

found in both animal and plant foods

Question 3

essential fatty acids

Answer 3

linoleic and linolenic acid, found in most vegetables, must be ingested

Question 4

fatty deposits in adipose tissues provide

Answer 4

-a protective cushion around body organs
-an insulating layer beneath the skin
-an easy-to-store concentrated source of energy

Question 5

Dietary fats

Answer 5

-help body to absorb vitamins
-are a major energy fuel hepatocytes and skeletal muscle
-Are a component of myelin sheaths and all cell membranes

Question 6

prostaglandins function in

Answer 6

-smooth muscle contraction
-control of blood pressure
-inflammation

Question 7

cholesterol

Answer 7

stabilizes membranes and is a precursor of bile salts and steroid hormones

Question 8

the liver

Answer 8

-Synthesizes lipoproteins for transport of cholesterol and fats
-Makes tissue factor, a clotting factor
-Synthesizes cholesterol from acetyl CoA
-Uses cholesterol to form bile salts

Question 9

certain endocrine organs

Answer 9

use cholesterol to synthesize steroid hormones

Question 10

sphingolipids

Answer 10

often found in neural coverings

Question 11

ester bonds

Answer 11

how fatty acids are linked

Question 12

both glycerol and fatty acids

Answer 12

are metabolized in distinct ways

Question 13

cells obtain fatty acid fuel from 3 sources

Answer 13

-fats consumed in the diet
-fats stored in cells as lipid droplets
-fats synthesized in one organ for export to another

Question 14

most products of fat metabolism

Answer 14

are transported in lymph as chylomicrons

Question 15

cytosol

Answer 15

glycolysis
pentose phosphate pathway
fatty acid synthesis

Question 16

mitochondrial complex

Answer 16

citric acid cycle
oxidative phosphorylation
ketone body formation
beta oxidation of fatty acids

Question 17

interplay of both cytoplasm and mitochondria

Answer 17

gluconeogenesis
urea synthesis

Question 18

lipids in chylomicrons are

Answer 18

hydrolyzed by plasma enzymes and absorbed by cells

Question 19

only neutral fats

Answer 19

are routinely oxidized for energy

Question 20

catabolism of fats involves two seperate pathways

Answer 20

glycerol pathway
fatty acid pathway

Question 21

major component of chylomicron

Answer 21

triglycerides

Question 22

phospholipid surface

Answer 22

polar headgroups face outward

Question 23

trglycerols are found in the interior

Answer 23

make up >80% of the mass

Question 24

Apolipoproteins on exterior

Answer 24

serve as signals for chylomicron uptake & metabolism

Question 25

Glycerol is converted to glyceraldehyde 3-phosphate (GAP)

Answer 25

-GAP is ultimately converted into acetyl CoA -Acetyl CoA enters the Krebs cycle

Question 26

Fatty acids undergo beta oxidation which produces

Answer 26

-Two-carbon acetic acid fragments, which enter the Krebs cycle -Reduced coenzymes, which enter the electron transport chain

Question 27

lipids hydrolyze triacylglycerols

Answer 27

-free fatty acids -glycerol

Question 28

fatty acids form acetyl coa

Answer 28

-citric acid cycle

Question 29

glycerol phosphorylated

Answer 29

oxidized to DHAP converted to GAP

Question 30

GAP enters glycolysis

Answer 30

payoff phase

Question 31

3 steps are required for fatty acid breakdown

Answer 31

1. Lipids must be mobilized: triglycerols degraded into fatty acids & glycerol. Subsequently released from adipose tissue into energy-requiring tissues. 2. Fatty acids must be activated and transported into mitochondria for degradation. 3. Fatty acids broken down, step-by-step, into acetyl-CoA which is fed into the Krebs/TCA cycle.

Question 32

mobilization of triglycerols

Answer 32

triglycerols degrades into fatty acids and glycerol. Subsequently released from adipose tissue into energy requiring tissue

Question 33

low blood glucose

Answer 33

stimulates glucagon release

Question 34

Glucagon activates receptor-G protein-adenylate cyclase system

Answer 34

activates hormone-sensitive lipases (HSL)

Question 35

PKA phosphorylation of perilipin permits

Answer 35

access of HSL to triglycerols in fat droplets

Question 36

Fatty acids released from adipocyte into bloodstream

Answer 36

bind to serum proteins, transported to other cells (i.e., myocytes) for use as energy source

Question 37

hormone sensitive lipase

Answer 37

responsive to glucagon and insulin

Question 38

activation of fatty acids

Answer 38

and transportation into mitochondria for degradation

Question 39

carnitine is converted to acyl carnitine

Answer 39

acyl carnitine is brought into cell where it is converted back to carnitine

Question 40

stage 1 of fatty acid oxidation

Answer 40

beta oxidation of fatty acids

Question 41

stage 2

Answer 41

acetyl CoA oxidized to CO2

Question 42

stage 3

Answer 42

electrons transferred from NADH/FADH2 to ETC for ATP synthesis

Question 43

degradation of even-numbered saturated fatty acids into acetyl-CoA

Answer 43

respective sequence of: -oxidation -hydration -oxidation -thiolysis

Question 44

trans delta 2 enoyl CoA

Answer 44

very important intermediate for even and odd degradation

Question 45

oxidation of palmitate

Answer 45

produces 8 molecules of acetyl CoA

Question 46

b-Oxidation of Monounsaturated Fatty Acids

Answer 46

requires 1 additional enzyme:enoyl-CoA isomerase and loses 2 ATP per double bond

Question 47

ß-Oxidation of Polyunsaturated Fatty Acids

Answer 47

Requires 1 additional enzyme (in addition to the additional enoyl CoA isomerase required for monounsaturated): 2,4-dienoyl-CoA reductase lose 3 ATP per additional double bond

Question 48

ß-Oxidation of Odd-Chain Length Fatty Acids

Answer 48

Same as oxidation of saturated FA’s but end with 3C converted to succinyl CoA

Question 49

excess dietary glycerol and fatty acids undergo lipogenesis to form

Answer 49

triglycerides

Question 50

glucose easily converts to fats since acetyl coa is

Answer 50

An intermediate in glucose catabolism The starting molecule for the synthesis of fatty acids

Question 51

lipolysis

Answer 51

the breakdown of stored fat, is essentially lipogenesis in reverse

Question 52

Oxaloacetate

Answer 52

necessary for the complete oxidation of fat otherwise ketogenesis begins

Question 53

When diet provides carbohydrate fuel

Answer 53

oxidation of fats is unnecessary

Question 54

Two enzymes key for coordinated regulation

Answer 54

1) acetyl-CoA carboxylase (ACC) 2) carnitine acyl transferase I

Question 55

ACC

Answer 55

first enzyme in FA synthesis pathway

Question 56

Carnitine acyl transferase I

Answer 56

regulates transport of FA into mitochondrial matrix for b-oxidation

Question 57

high carb meal

Answer 57

stimulates insulin release

Question 58

Insulin-dependent protein phosphatase

Answer 58

dephosphorylates ACC (activates enzyme)

Question 59

ACC catalyzes

Answer 59

formation of malonyl-CoA (first intermediate in FA synthesis)

Question 60

Malonyl-CoA inhibits

Answer 60

carnitine acyltransferase I (prevents FA entry into mitochondrial matrix)

Question 61

When blood glucose drops between meals

Answer 61

Glucagon release activates PKA PKA phosphorylates ACC (inactivates enzyme) Malonyl-CoA levels decrease (FA entry into mitochondria is restored) FA oxidation in mitochondria major form of fuel Glucagon also stimulates mobilization of FA from adipose tissue, FA available from bloodstream