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Biochemistry 2 > Fatty acid oxidation > Flashcards

Fatty acid oxidation Flashcards

1
Q

how can we fast for up to 2 weeks at a time?

A

we can store dietary fuels and break them down into ATP

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2
Q

fatty acids

A

long chains of carbon and hydrogen

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3
Q

how do fatty acids generate ATP?

A

transfer of electrons in form of hydrogens to molecules can generate ATP

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4
Q

where does fatty acid oxidation occur?

A

mitochondria of heart, liver, skeletal muscle cells

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5
Q

where is fat stored?

A

in adipocytes as triglycerides

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6
Q

triglyceride

A

3 fatty acids attached to glycerol

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7
Q

what enzyme breaks down triglycerides?

A

Hormone sensitive lipase breaks triglycerides down into 3 fatty acids + glycerol

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8
Q

starvation state

A

blood glucose decreases, pancreas secretes glucagon which increases activity of hormone sensitive lipase

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9
Q

what hormone increases activity of hormone sensitive lipase?

A

increase in glucagon!

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10
Q

once broken down by hormone sensitive lipase, what happens

A

fatty acids can leave fat cell and enter blood stream and bind to albumin

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11
Q

albumin does what with fatty acids?

A

takes them to target cells, such as liver cells that can perform fatty acid oxidation
also makes them more soluble

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12
Q

fatty acid oxidation getting into the cell

A

fatty acid dissociates from albumin and diffuses into cell

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13
Q

carnitine shuttle step 1

A

enzyme: fatty acyl-CoA synthetase
fatty acid to fatty acyl-coa
requires 2 ATP + CoA
ATP to AMP and PPi

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14
Q

mitochondrial matrix

A

core of mitochondria
contains enzymes for beta-oxidation
BUT fatty acyl-CoA can’t cross mitochondrial membrane while CoA is attached

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15
Q

carnitine shuttle step 2

A

fatty acyl-CoA to fatty acyl-carnitine +CoA (now can cross mito membrane)
enzyme: carnitine acyltransferase 1 (CAT1) replaces CoA with carnitine

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16
Q

carnitine shuttle step 3

A

once inside matrix, CAT2 puts CoA where carnitine is. regenerating fatty acyl-CoA and free carnitine

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17
Q

carnitine shuttle purpose

A

carnitine can go back and forth through mitochondrial matrix to bring in more fatty acids

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18
Q

where do we get carnitine from?

A

diet! mainly meat

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19
Q

carnitine shuttle regulation

A

malonyl-CoA (from fatty acid synthesis) can inhibit CAT1 and slow down fatty acid oxidation

20
Q

alpha and beta carbons of fatty acid chain

A

2nd (alpha) and 3rd (beta) carbons of chain

21
Q

fatty acid oxidation step 1a

A

palmitoyl-CoA to enoyl-CoA
enzyme: acyl-CoA dehydrogenase removes 1 hydrogen from alpha and beta carbons
gives hydrogens to FAD to make FADH2

22
Q

fatty acid oxidation step 1b

A

enoyl-CoA to beta-hydroxyacyl-CoA

enoyl-CoA hydratase uses H2O to add OH to beta carbon

23
Q

fatty acid oxidation step 2

A

beta-hydroxyacyl-CoA to beta-ketoacyl-CoA
enzyme: beta-hydroxyacyl-CoA
NAD+ to NADH

24
Q

fatty acid oxidation step 3

A

beta-ketoacyl-CoA to acetyl-CoA

enzyme: beta-ketothiolase

25
Q

beta oxidation 1 cycle energy payoff

A

1 NADH, 1 FADH2, 1 acetyl-CoA

26
Q

where do NADH and FADH2 go?

A

ETC! bc they are electron rich
they can make ATP
1 NADH = 3 ATP
1 FADH2 = 2 ATP

27
Q

where does the 1 acetyl-CoA go?

A

citric acid cycle to yield NADH and FADH2 which then enter ETC and yield 12 ATP per acetyl-CoA

28
Q

1 palmitoyl-CoA yields

A

7 NADH
7 FADH2
8 acetyl-CoA
131 ATP - 2 ATP = 129 ATP

29
Q

odd-chain fatty acids…what is different?

A

same process until we have 3 carbon molecule left (propionyl-CoA)

30
Q

what does propionyl-CoA get converted to

A

succinyl-CoA

a TCA cycle intermediate

31
Q

where does succinyl-CoA go (2 options)

A

1) enter TCA cycle and become oxaloacetate (extra oxaloacetate can be used in gluconeogenesis)
2) succinyl-CoA can be fully oxidized to CO2

32
Q

fatty acid oxidation summary (3 steps)

A

1) activation
2) carnitine shuttle
3) beta-oxidation

33
Q

what triggers release of fatty acids from TAGs?

A

adrenaline, glucagon, and ACTH can activate lipases that release fatty acids from TAGs

34
Q

what happens to glycerol when fatty acids are broken down?

A

glycerol goes back to liver and can be converted to DHAP for gluconeogenesis

35
Q

fatty acids from diet

A

dietary TAGs are degraded in duodenum with aid of lipases from the pancreas

fatty acids enter intestinal cells and are re-packaged as chylomicrons for transport in blood

36
Q

beta oxidation rxn 1

A

1) form double bond by acyl-CoA dehydrogenase

37
Q

beta oxidation rxn 2

A

2) hydrate double bond by enoyl-CoA hydratase

38
Q

beta oxidation rxn 3

A

3) oxidation by hydroxyl-CoA dehydrogenase

39
Q

beta oxidation rxn 4

A

4) cleavage of beta-keto ester to release acetyl-CoA and acyl-CoA

40
Q

acyl-CoA dehydrogenase

A

tightly bound to FAD

electrons picked up by FAD are moved into ETC via UQH2

41
Q

oxidation of palmitate (16C) yields…

A

106 ATP
costs 2 ATP to activate fatty acid
yield is 100 ATP via ETC/ox phos and 8 ATP from TCA cycle

42
Q

how many ATP per NADH or FADH2

A
  1. 5 ATP per NADH

1. 5 ATP per FADH2

43
Q

fatty acid oxidation: anaerobic or aerobic?

A

aerobic: requires oxygen!

44
Q

when do we use more fatty acids as fuel

A

long duration = use more fats

higher intensity = more carbs as fuel

45
Q

ketone bodies

A

alternate source of fuel
produced in liver mitochondria (ketosis or ketogenesis)
can’t be used by liver!
transported in blood for use by other tissues

46
Q

ketone bodies unique facts

A

soluble form of fats
can cross blood-brain barrier (can be used by brain when glucose is unavailable)
EX: starvation/low carbs or Diabetes Mellitus

47
Q

ketoacidosis

A

caused by very high amounts of ketone bodies in blood
acidify blood, put strain on kidney
occurs during uncontrolled diabetes mellitus (without insulin, cells can’t use glucose in body)
fatty acids broken down and acetyl-CoA used to produce ketone bodies

Biochemistry 2 (32 decks)

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