FA Oxidation and Ketone Bodies Flashcards Preview

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Flashcards in FA Oxidation and Ketone Bodies Deck (60):
1

FA oxidation occurs where?

in mitochondria

2

True or false? Long-chain FAs can't enter the mitochondria without transport mechanisms. Medium and short-chain FAs can enter by diffusion.

true

3

Medium-chain and short-chain FAs are more water soluble. They are not incorporated into ____. They enter the portal blood and are transported primarily to the ____ where they enter by _____.

chylomicrons; liver; diffusion

4

In the mitochondria, medium and short-chain FAs are activated to ___-___ for beta-oxidation

acyl-CoAs

5

FA binding proteins in the plasma membrane aid in the transport of long-chain FAs from ___ in the blood

albumin

6

Long-chain FAs enter the mitochondria as fatty _____

acylcarnitines

7

A fatty acyl-CoA synthase on the ___ mitochondrial membrane produces acyl-CoAs which enter the mitochondrial ____-membrane space

outer; inter

note: CPT I catalyzes this reaction

8

_____ are transported across the mitochondrial inner membrane in exchange for "free" _____ by cranitittine:acylcarnitine translocase

acylcarnitines; carnitine

9

Inside the mitochondria, the acyl-CoA is "____" by CPT II

"regenerated"

10

Beta-oxidation of long-chain acyl-CoAs is a series of 4 reactions repeated cyclically. Each cycle produces how many acetyl-Coa, FADH2, NADH, and acyl-CoA

acetyl-CoA: 1
FADH2: 1
NADH: 1
acyl-CoA: one reduced in length by 2 carbons

11

Since the 4 reactions of beta-oxidation occur inside the mitochondria, the reduced cofactors are substrates for ____ ____, and the acetyl-CoA is a substrate for the ____ ____

oxidative phosphorylation; TCA cycle

12

Each of the 4 reactions in beta-oxidation is catalyzed by a number of enzymes which have various specificities for chain length. For the following acyl-CoA dehydrogenase, give the light of chain it prefers.
VLCAD
LCAD
MCAD
SCAD

VLCAD: prefers C12 to C24
LCAD: C12 to C16
MCAD: C6 and C8
SCAD: C4>C6>C8

13

The major control of beta-oxidation is exerted at which enzyme?

CPT I

14

CPT I is inhibited by ____-___

malonyl-CoA

15

Malonyl-CoA is the produce of ___-___ carboxylase and is the substrate for FA ____

acetyl-CoA; synthesis

16

Acetyl-CoA carboxylase is stimulated (malonyl-CoA is produced) in what situation?

when insulin predominates

17

Acetyl-CoA carboxylase is inhibitied (malonyl-CoA concentration decreases) in what situation?

when glucagon predominates

18

How do odd-numbered FAs go through Beta-oxidation?

1. at the final stage, one molecule of acetyl-CoA and one molecule of propionyl-CoA are produced
2. propionyl-CoA is converted to succinyl-CoA

19

____-___ is a gluconeogenic precursor, and thus the only part of a FA which can result in the net synthesis of glucose

Succinyl-CoA

20

Oxidation of unsaturated FAs have to be handled differently because the double bonds are in the ____ configuration and may involve an ___-numbered carbon

cis; odd

21

Unsaturated FAs are oxidized with help from two enzymes. What are they?

1. enoyl-CoA isomerase
2. 2,4-dienoyl-CoA reductase

22

Where does oxidation of very long chain FAs (C24-C26) occur?

peroxisomes

note: called "modified" beta-oxidation

23

What are the products of very long chain FA "modified" beta oxidation?

acetyl-CoA and a fatty acyl-CoA reduced by 2 carbons

24

The acyl-CoA oxidation in modified beta oxidation is not linked to cofactor ____

reduction; means no energy is provided by this step

25

The peroxisomal oxidation (modified beta oxidation) proceeds until the acyl-CoA is about ___ carbons long

8

26

The octanoyl-CoA and the acetyl-CoA produced by peroxisomal oxidation are transported to the ____ for further oxidation

mitochondria

27

True or false? animals do not produce branched-chain fatty acids

true

28

The most common long-chain branched FA is a degradation product of ____

chlorophyll

29

long-chain branched FAs are oxidized where?

peroxisomes

30

What are the products of long-chain branched FA oxidation?

1. CO2
2. propionyl-CoA
3. acetyl-CoA

31

In regards to w-oxidation of FAs, the w-carbon is the terminal ___ group of the FA

methyl

32

w-oxidation occurs where? requires what?

occurs in ER
requires cytochrome P450, O2, and NADPH

33

The w-CH3 group is oxidized first to an ____ and then to a ____ ___

alcohol; carboxylic acid

note: produces a dicarboxylic acid

34

The w-oxidation pathway is though to function to produce more water-soluble compounds from water insoluble FAs. The products may be oxidized as ___-chain FAs or they can be ___

medium; excreted

35

Ketone bodies are formed from ___-___ from FA oxidation

acetyl-CoA

36

Name the 3 ketone bodies

acetoacetate, beta-hydroxybutyrate; acetone

37

The ketone bodies are synthesized in ____ ____

liver mitochondria

38

___-___ is an intermediate in the ketone body pathway

HMG-CoA

39

The liver mitochondrial HMG-CoA synthase is an isozyme restricted to the mitochondria and functions only in what?

synthesis of ketone bodies

40

The cytosolic HMG-CoA synthase of many cells is the isozyme of ____ synthesis

cholesterol

41

Ketone bodies are utilized by peripheral tissues for energy - primarily the ___ and ____

muscle and brain

note: the enzymes are mitochondrial

42

The ___ only produces ketone bodies, and the ___ ___ only utilizes ketone bodies

liver; peripheral tissue

43

Only liver mitochondria contain the enzymes specific for the synthesis of ketone bodies. What are they?

1. mitochondrial HMG-CoA synthase
2. HMG-CoA lyase

44

Peripheral tissues (muscle and brain) express the enzyme specific for utilization of ketone bodies. What is it?

acetoacetate: succinyl-CoA transferase

45

True or false? ketone bodies are formed in the liver only when the liver is supplied with high concentrations of FAs

true

46

Where do the FAs used to synthesize ketone bodies come from?

lipolysis of adipose tissue

47

In what individuals is ketone body production usually seen?

starving or uncontrolled type 1 diabetes

48

After an over night fast, the concentration of ketone bodies in the blood is on the order of ____ mM. After a 2 day fast? After 40 days of starvation?

overnight: 0.05
2 days: 2mM
40 days: 7mM

49

____ is derived from the spontaneous, non-enzymatic decarboxylation of acetoacetate

acetone

50

The amount of FAs provided to the liver is under the control of ____ and ____

insulin and glucagon

51

This is the most common genetic disease of lipid metabolism (1/15000). It is associated with non-ketotic hypoglycemia upon fasting, fatty infiltration of liver, and short chain dicarboxylic acids in urine

MCAD (medium-chain acyl-CoA dehydrogenase) deficiency

52

In regards to MACD, non-ketotic hypoglycemia upon fasting may be deadly in an overnight fast of which individuals?

children

53

In regards to MACD, Fatty acids which cannot be oxidized are assembled into ____ which exceed the ability of the liver to secrete as ___

TAG; VLDL

54

In regards to MACD, the short chain dicarboxylic acids in the urine arise from where?

w-ocidation of medium and short chain fAs which can't be oxidized by beta-oxidation

55

What is the treatment of MACD?

avoid fasting

56

In this disorder of lipid oxidation, insufficient FAs are delivered into the mitochondria. Symptoms include non-ketotic hypoglycemia due to decreased energy for gluconeogenesis

carnitine deficiency

57

In this disorder of lipid oxidation, symptoms include non-ketotic hypoglycemia due to decreased beta-oxidation, hepatomegaly with fatty infiltration, increased plasma carnitine. It can be overcome by medium-chain FAs

CPT I deficiency

58

This disorder of lipid oxidation can be described by a rare genetic deficiency of a component required for peroxisomal oxidation of branched-chain FAs. Its associated with serious neurological issues.

Refsum disease

59

How is Refsum disease treated?

by reducing phytanic acid from diet (restrict dairy and meat)

60

This disorder of lipid oxidation is due to eating the unripe fruit of the akee tree, which contains hypoglycin - It is a potent inhibitor of acyl-CoA dehydrogenase. Symptoms are non-ketotic hypoglycemia

Jamaican vomitting sickness

note: one case reported a blood glucose concentration of 3 mg/dl