Chapter 17

Question 1

Four major functions of lipids

Answer 1

structural components
energy reserves
vitamins
hormones

Question 2

Summary of how lipids are transported

Answer 2

from the intestine as chylomicrons to the liver and other tissues
other tissues to liver as HDL
leaves the liver as VLDL that changes into LDL
LDL then moves to other tissues and the liver

Question 3

Triaglycerols

Answer 3

glycerol bonded to three fatty acids
main storage form of fat

Question 4

The release of fatty acids from triacylglycerols and phosphoacylglycerols is catalyzed by

Answer 4

lipases

Question 5

the breakdown of a triacylglycerol creates

Answer 5

three fatty acids

Question 6

Phospholipases D’s

Answer 6

destroy cell membranes

Question 7

The release of fatty acids in adipocytes is under

Answer 7

hormonal control- epinephrine
cyclic AMP begins a kinase cascade that leads to phosphorylation and activation of the lipases

fatty acids are released and can then be oxidized to produce ATP in the mitochondria

Question 8

Fatty acids are oxidized via _____ to produce ____

Answer 8

beta- oxidation
acetyl-CoA

Question 9

Beta oxidation takes place in the

Answer 9

mitochondria

Question 10

Acetyl CoA is used to generate energy via the

Answer 10

citric acid cycle
electron transport chain

Question 11

Fatty acid activation

Answer 11

two steps catalyzed by acyl-CoA synthetase

Question 12

A repeated sequence of four reaction that occur in the mitochondrial matrix

Answer 12

Beta oxidation of fatty acids

Question 13

Goals of beta oxidation

Answer 13

1. create a carbonyl group on the beta carbon by shortening the acyl group by two carbons
   - removed as acetyl-CoA
2. generate energy by producing the reduced electron carriers FADH2 and NADH

Question 14

The first reaction of beta oxidation

Answer 14

electron transfer reactions

Question 15

The second reaction of Beta oxidation

Answer 15

addition of water

Question 16

The third reaction of beta oxidation

Answer 16

NAD+ cofactor

Question 17

fourth reaction of beta oxidation

Answer 17

release of acetyl-CoA

Question 18

Beta oxidation- Electron transfer reactions are catalyzed by

Answer 18

acyl-CoA dehydrogenase

Question 19

Beta oxidation- addition of water is catalyzed by

Answer 19

hydratase

Question 20

Beta oxidation- NAD+ cofactor is catalyzed by

Answer 20

another dehydrogenase

Question 21

Beta oxidation- release of acetyl-CoA is catalyzed by

Answer 21

thiolase

Question 22

Energy yields from beta oxidation

Answer 22

1 NADH, 1 FADH2 and 1 acetyl-CoA

NADH and FADH2 generate ATP via electron transport chain and ATP synthase
acetyl-CoA enter the citric acid cycle to generate 1 FADH2, 3 NADH, 1 GTP

Total ATP 120

Question 23

Fats are more ______ than sugars and amino acids

Answer 23

reduced

Question 24

Beta oxidation of fatty acids steps

Answer 24

1. oxidation of beta carbon generated FADH2
2. Hydration of beta carbon generates -OH groups
3. oxidation of beta carbon generates NADH and a carbonyl group
4. cleavage between the alpha and beta carbons and formation of acetyl-CoA
   5 further cycles

Question 25

Fatty acyl-CoA is shortened by 2 carbons from the

Answer 25

carbonyl end

Question 26

Beta oxidation repeats until

Answer 26

there are just two carbons left

Question 27

Fatty acids with ___ double bonds pose a problem for enzymes in beta oxidation

Answer 27

cis

Question 28

Cis double bonds are turned into trans double bonds by what enzyme

Answer 28

isomerase

Question 29

Why do unsaturated fatty acids yield less free energy than saturated fatty acids

Answer 29

creates fewer FADH2 due to having to use an isomerase to change a cis bond to a trans bond

Question 30

ODD chain length fatty acids beta oxidation difference

Answer 30

occurs until three carbons are left propionyl-CoA created at the end

Question 31

in order to enter the citric acid cycle propionyl-CoA (created by odd numbered chain) must go through

Answer 31

carboxylation to methyl-malony-CoA and rearrangement to succinyl-CoA

Question 32

Beta oxidation of fatty acids produces metabolic water how?

Answer 32

FADH2 and NADH produce water in the electron transport chain

Question 33

Peroxisomes

Answer 33

enclosed by a single membrane and contain a variety of degradative and biosynthetic enzymes

Question 34

How does fatty acid oxidation in peroxisomes differ from that in mitochondria

Answer 34

enoyl-CoA product of the reaction is identical to the product of the mitochondrial acyl-CoA dehydrogenase reaction

Question 35

What happens if we don't consume carbs

Answer 35

no glycolysis rely on fatty acids for acetyl-CoA Liver does gluconeogenesis making glucose TCA stops because acetyl-CoA directed to make glucose for the brain

Question 36

In long fasts and starvation oxaloacetate is

Answer 36

consumed to make glucose by the gluconeogenic pathway so acetyl CoA accumulates

Question 37

Increased acetyl CoA makes

Answer 37

acetoacetate beta hydroxybutyrate acetone All of these are ketone bodies

Question 38

Ketone bodies are made

Answer 38

in the liver mitochondria

Question 39

Production of ketone bodies

Answer 39

two acetyl-CoA are condensed to acetoacetyl-CoA Another condensation with acetyl-CoA produces hydroxyl-alpha-methylglutaryl-CoA HMG-CoA lyase releases acetyl-CoA to produce acetoacetate Acetoacetate is either decarboxylated to acetone or reduced to alpha hydroxybutyrate

Question 40

Ketone bodies are used by the

Answer 40

brain as a fuel source during starvation

Question 41

Why is an excess of ketone bodies bad?

Answer 41

are acidic and can lower the pH of the blood Ketoacidosis - increased thirst, secretion of H+ into the urine - symptom of untreated diabetes (type 1)

Question 43

Anabolism of fatty acids happens in the

Answer 43

cytosol

Question 44

Anabolism of fatty acids is/is not a simple reversal of beta oxidation

Answer 44

NOT

Question 45

First step of anabolism is

Answer 45

exporting acetyl-CoA from the matrix to the cytoplasm via a citrate intermediate

Question 46

Formation of the main precursor to fatty acid synthesis of _____ is from the carboxylation of acetyl-CoA

Answer 46

malonyl-CoA

Question 47

Formation of malonyl-CoA is catalyzed by

Answer 47

acetyl-CoA carboxylase (ACCase) complex

Question 48

ACCase requires

Answer 48

biotin, Mn2+, and ATP

Question 49

Fatty acid synthesis priming groups

Answer 49

1. two carbon acetyl group that will be lengthened is transferred from CoA to a Cys side chain of fatty acid synthesis 2. malonyl group will donate an acetyl group to the growing fatty acyl chain is transferred from CoA to the ACP domain of the enzyme

Question 50

Subsequent steps of fatty acid synthesis

Answer 50

3. condensation reaction- malonyl group is decarboxylated and the resulting two-carbon fragment attacks the acetyl group to form a four-carbon product 4. 3-ketoacyl product of step 3 is reduced 5. dehydration introduces a 2,3 double bond 6. second NADPH dependent reduction completes the conversion of the condensation product to an acyl group 7. acyl group is transferred from ACP to enzymes Cys group another malonyl group is loaded onto the free ACP ready for another condensation reaction

Question 51

free fatty acids are mostly found

Answer 51

incorporated within triacylglycerols and phosphoacylglycerols synthesis of these compound occurs in the endoplasmic reticulum of liver or fat cells

Question 52

main point of regulatory control for fatty acid metabolism

Answer 52

ACCase

Question 53

phospholipid synthesis

Answer 53

1. ATP phosphorylates the OH group of ethanolamine or choline 2. phosphoryl group attacks CTP to form CDP-ethanolamine or CDP-choline. PPi product is hydrolyzed 3. the C3 OH group of diacylglycerol displaces CMP to generate the glycerophospholipid

Question 54

Phosphatidylserine synthesis

Answer 54

head-group exchange reaction

Question 55

Phosphatidylinositol synthesis

Answer 55

1. phosphatidase attacks CTP to form CDP- diacylglycerol 2. an inositol group displaces CMP to produce phosphatidylinositol

Question 56

Every carbon of cholesterol is derived from

Answer 56

acetyl-CoA carbons

Question 57

Cholesterol is stored as

Answer 57

an ester changed using acyl-CoA (cholesterol acyltransferase)

Question 58

Cholesterol synthesis inhibitors

Answer 58

Lipitor lovastatin simvastatin

Question 59

The body coordinates cholesterol production and transport among tissues

Answer 59

SREBP regulatory system

Question 60

Steroid hormones are synthesized from

Answer 60

cholesterol