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Metabolism > #8 > Flashcards

#8 Flashcards

1
Q

What 2 things are of interest as important energy sources in lipid metabolism?

A

fatty acids and triacylglycerols

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2
Q

Fatty acids and triglycerols have a similar relationship to each other as what 2 things?

A

glucose and glycogen

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3
Q

____ are present in the body but in smaller
quantities than ____

A

fatty acids, triaglycerols

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4
Q

What can fatty acids be derived from when needed?

A

triaglycerols

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5
Q

What is our primary focus in lipid metabolism?

A

fatty acid metabolism

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6
Q

What are triaglycerols synthesized from?

A

activated forms of glycerol and fatty acids

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7
Q

What is an activated form of glycerol? What is this derived from?

A

glycerol-3-phosphate, dihydroxyacetone phosphate

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8
Q

Activated fatty acid is ____
Fatty acid + ____
What does this require?
ATP hydrolyzed to ____
Catalyzed by what?

A

Acyl CoA
CoA-SH
input of injury
AMP+PPi
Acyl CoA synthetase

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9
Q

Activated substances (__ and __) and joined with the attachment of two ___ to positons 1 and 2 of glycerol-3-phosphate
What is this catalyzed by?

A

glycerol-3-phosphate and acyl
CoA, acyl groups
glycerol phosphate acyltransferase

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10
Q

Phosphatidate is converted to ____ after losing its ____ group and accepting a third ____ group derived from another acyl CoA

A

triaglycerol, phosphoryl, acyl

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11
Q

what is the previous reaction catalyzed by?

A

triaglycerol synthase

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12
Q

What is triaglycerol breakdown called?

A

lipolysis

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13
Q

What type of reaction happens in lipolysis? What 2 lipases is this catalyzed by?

A

cytosolic reaction, TRIACYLGLYCEROL LIPASE
MONOACYLGLYCEROL LIPASE

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14
Q

What does triaglycerol lipase catalyze?
What are the products?

A

catalyzes the hydrolysis of the
ester linkages at position 1 and 3 of the glycerol unit
products: 2-monoacylglycerol, Two fatty acids

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15
Q

____ then hydrolyzes the the ester linkages at ____

A

Monoacylglycerol, position 2 of the glycerol

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16
Q

What is the end product of lipolysis?

A

one triaglycerol: 3 fatty acids and one glycerol

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17
Q

What is fatty acid degradation degraded through?

A

β-oxidation

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18
Q

Where does fatty acid degradation occur? What must fatty acids cross?

A

mitochondria, 2 mitochondrial membranes

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19
Q

Fatty acids must be activated by being converted to what? What process is this similar to?

A

acyl CoA, process in TG synthesis

20
Q

What membranes can most acyl CoA that are formed cross?

A

can readily cross the outer mito membrane (but not the inner membrane)

21
Q

How many carbons are in an acyl group?

A

greater than or equal to 14

22
Q

____ must be used to transfer the acyl groups
across the inner membrane and into the matrix

A

Carnitine

23
Q

Carnitine detaches the ____ from ____ forming ____
What is this catalyzed by?

A

acyl group, acyl CoA, acyl carnitine
CARNITINE ACYLTRANSFERASE I

24
Q

Acyl carnitine then crosses the inner mito membrane
with the help of ____

A

TRANSLOCASE

25
Q

In the mito matrix, the acyl group is again linked to ____, what happens to carnitine?

A

CoA, displaces carnitine

26
Q

After Acyl CoA is in the mito matrix where does carnitine return to?

A

to the intermembrane space through translocase in
exchange for entry of acyl carnitine

27
Q

Once in the matrix what pathway does acyl CoA enter?

A

β-oxidation pathway

28
Q

Series of reactions detaching two carbons as ____ from the ____ of the fatty acid

A

acetyl CoA, carboxyl end

29
Q

in step 1 beta oxidation dehydration what is the hydrogen acceptor and what is formed?

A

FAD, FADH2

30
Q

What was the previous reaction catalyzed by?
What is the product?

A

Catalyzed by ACYL CoA DEHYDROGENASE
Product: Enoyl CoA

31
Q

In step 2 beta oxidation hydration what is added?

A

H2O molecule

32
Q

What is the previous reaction catatlyzed by? What is the product?

A

Catalyzed by ENOL CoA HYDRATASE
Product: L-3-Hydroxyacyl CoA

33
Q

In step 3 beta oxidation this is another what?
What is the hydrogen acceptor and what is formed?

A

another dehydrogenation
NAD+, NADH

34
Q

What is the previous reaction catalyzed by? what is the product?

A

Catalyzed by HYDROXYACYL CoA DEHYDROGENASE
Product: 3-Ketoacyl CoA

35
Q

In step 4 beta oxidation splitting what is used in this reaction?

A

CoA

36
Q

What is the previous reaction catalyzed by?
What are the products?

A

Catalyzed by THIOLASE
Products: Acetyl CoA and Original Acyl CoA minus 2
carbons

37
Q

What are the products of one round of beta oxidation?

A

One acyl CoA (shortened by 2 carbons)
One aetyl CoA
One FADH2
One NADH

38
Q

A new round of β-oxidation follows which again
shortens what?
Why is this process repeated?

A

the acyl CoA by 2 more carbons
Process is repeated as many times as it takes to
degrade a fatty acid

39
Q

End products of β-oxidation are then metabolized where?

A

the mitochondria

40
Q

What enters the Krebs Cycle and what is it oxidized to? What does this yield?

A

Acetyl CoA, 2 CO2
Yields 3 NADH, 1 FADH2, 1 GTP

41
Q

Where are NADH and FADH2 from oxidation (and Krebs) oxidized?

A

in the ETC

42
Q

The glycerol released by lipase action is
phosphorylated to yield ____

A

glycerol-3-phosphate

43
Q

What was the previous reaction catalyzed by?

A

glycerol kinase

44
Q

Glycerol-3-phosphate is then oxidized to ____
This is an intermediate of what?

A

dihydroxyacetone phosphate
intermediate of both glycolysis and gluconeogenesis

45
Q

What are ketones used for?

A

During carbohydrate starvation
(fasting, diabetes, prolonged
exercise) ketone bodies can be
used as fuel

46
Q

Liver catabolizes fat to ____
then converts it to ____

A

acetyl-CoA, ketones

47
Q

Ketones are released into the
circulation and taken up by what?

A

brain,
muscle, nerves

Metabolism (6 decks)

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