Chapter 16- Fatty Acids and Eicosanoids Flashcards Preview

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Flashcards in Chapter 16- Fatty Acids and Eicosanoids Deck (55):
1

What is a positive modulator of lipolysis?

glucagon or epinephrine

2

What does CPTI do?

transport acyl-CoA into mitochondria

3

What is lipolysis?

hydrolysis of TAGs in adipocytes -> forms free FA

4

what is a negative modulator of CPTI?

malonyl-CoA

5

In ketogenesis Fatty acyl-CoA can be converted to

2 Acetyl-CoA or Acetoacetyl-CoA (beta-oxidation)

6

Acetoacetyl-CoA is synthesized from what?

2 acetyl-CoA catalyzed by thiolase in starvation

7

In fed state what is the fate of acetyl-CoA?

TCA cycle -> glucose via gluconeogenesis

8

In ketogenesis what is acetoacetyl-CoA converted to and by what enzyme?

HMG-CoA via HMG-CoA synthase

9

In ketogenesis what is HMG-CoA converted to and by what enzyme?

Acetoacetate via HMG-CoA lyase

10

In ketogenesis what is Acetoacetate converted to and by what?

spontaneously decarboxylated to acetone

converted to 3-hydroxybutyrate via 3-hydroxybutyrate dehydrogenase

11

Are ketones used by the liver?

No, the liver lacks succinyl-CoA-acetoacetate-CoA transferase so it cannot use ketone bodies

12

How does the body use ketone bodies?

when ketone bodies released from liver -> transported to muscle (major), kidney (major), brain (only in starvation) -> oxidized for energy

13

What is the rate limiting step in ketogenesis?

HMG-CoA reductase, release of FA from adipose and uptake of acyl-CoA into mitochondria (CPTI)

14

where does cholesterol synthesis occur?

liver cytosol

15

Where does ketogenesis occur

liver mitochondria

16

How is acetone excreted?

by lungs, expiration

17

How are ketone bodies excreted?

urine

18

Why does ketogenesis occur?

During gluconeogenesis acetyl-CoA uses oxaloacetate in the formation of citrate and eventually glucose. When oxaloacetate is depleted ketogenesis proceeds so acetyl-CoA can be utilized for energy.

19

Where is the major site of FA synthesis?

liver cytosol

20

Synthesis of long chain saturated FA is from?

Synthesized from dietary glucose via pyruvate

21

Where are enzymes for FA synthesis located?

The Es are localized in the cytosol, completely different from the mitochondrial Es for FA degradation

22

To synthesize palmitic acid, polymerization of initial 2 carbon units are from what

Acetyl-CoA, carbons 15, 16

23

What molecules are required for FA synthesis?

reduced NADPH, ATP, biotin, CO2, H2O

24

What is the initial and controlling step of FA synthesis?

production of Malonyl-CoA, carboxylation reaction and requires biotin

25

Describe FA synthase

a multi-enzyme complex, total of 8 reactions

26

General concept of LCFA synthesis?

keep adding 2 carbon until C16 (palmitic acid) then enzyme no longer has affinity and releases FA

27

How is acetyl-COa transported out of the mitochondria to be used for FA synthesis?

as citrate

28

Where do the additional 2 carbons that add onto acetyl-CoA's initial carbons come from?

malonyl-CoA, carbons 1-14

29

What are 4 essential unsaturated FA

palmitoleic acid (16:1)
oleic acid (18:1)
linoleic (18:2)
alpha-linolenic (18:3)

30

What do cis USFA provide?

fluidity of TG reserves, phospholipid membranes

Many serve as precursors of eicosanoids (prostaglandins, prostacyclins, thromboxanes, & leukotrienes)

31

Where and how are double bonds introduced

In the ER, double bonds are introduced between carbons 9 and 10 by FA oxygenase, which require molecular oxygen (O2) and NADPH

32

Arachidonic acid is the precursor of

PGs, TXs, PGIs, & LTs

33

Essential fatty acids are stored almost completely as

esters of the 2-position of the glycerol backbone of cell membrane phospholipids

34

essential fatty acids are released using what phospholipase in arachidonic acid synthesis?

phospholipase A2

35

Activation of PLA2 and PLC

Stimuli -> intracellular Ca2+ with calmodulin -> activate membrane bound phospholipase A2 and C

36

What drug inhibits phospholipase A2 activity?

glucocorticoids (i.e. cortisol)

37

Phospholipase A1 cleaves

at SN-1, first acyl group on glycerol backbone

38

Phospholipase A2 cleaves

at SN-2, first acyl group on glycerol backbone

39

Phospholipase C cleaves

cleaves phospholipids just before phosphate group

40

Phospholipase D cleaves

cleaves just after phosphate group freeing serine or choline or inositol or ethanol amine

41

name two Cox-2 inhibitors

celecoxib
rofecoxib

42

What is monteleukast used to treat?

treatment of allergen and exercise-induced asthma and allergic rhinitis

43

MOA of Zarfirlukast or monteleukast

leukotriene receptor antagonist

44

Biological activities of PGD2

inhibits platelet and leukocyte aggregation, decreases T-cell proliferation and lymphocyte migration and secretion of IL-1a and IL-2; induces vasodilation and production of cAMP

45

Biological activities of PGE2

increases vasodilation and cAMP production, enhancement of the effects of bradykinin and histamine, induction of uterine contractions and of platelet aggregation, maintaining the open passageway of the fetal ductus arteriosus; decreases T-cell proliferation and lymphocyte migration and secretion of IL-1a and IL-2

46

Biological activities of PGF2alpha

increases vasoconstriction, bronchoconstriction and smooth muscle contraction

47

Biological activities of PGH2

precursor to thromboxanes A2 and B2, induction of platelet aggregation and vasoconstriction

48

Biological activities of PGI2

inhibits platelet and leukocyte aggregation, decreases T-cell proliferation and lymphocyte migration and secretion of IL-1a and IL-2; induces vasodilation and production of cAMP

49

Biological activities of TxA2

induces platelet aggregation, vasoconstriction, lymphocyte proliferation and bronchoconstriction

50

Biological activities of TxB2

induces vasoconstriction

51

Biological activities of LTB4

induces leukocyte chemotaxis and aggregation, vascular permeability, T-cell proliferation and secretion of INF-γ, IL-1 and IL-2

52

Biological activities of LTC4

component of SRS-A, microvascular vasoconstrictor, vascular permeability and bronchoconstriction and secretion of INF-γ

53

Biological activities of LTD4

predominant component of SRS-A, microvascular vasoconstrictor, vascular permeability and bronchoconstriction and secretion of INF-γ

54

Biological activities of LTE4

component of SRS-A, microvascular vasoconstrictor and bronchoconstriction

55

What is tested/detected in asthmatic reactions?

LTE4