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Biochemistry II > Beta oxidation > Flashcards

Beta oxidation Flashcards

1
Q

How are fatty acids digested?

A
  1. Emulsification by bile salts
  2. Degraded by lipases
  3. Converted to triacylglycerols
  4. Packaged into chylomicrons for transport
  5. Travel to target tissues
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2
Q

In what cases or places is degradation of fats used as a major source of energy?

A

Heart muscle

Resting skeletal muscle

Liver

Hibernating animals

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3
Q

The products of triacylglycerol hydrolysis are glycerols, which can enter _________________ or ________________, and fatty acids, which can enter ____ _______________.

A

Glycolysis

Gluconeogenesis

Beta oxidation

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4
Q

Fats are mobilized from lipid dropets through a _________________ ________________ in the adipocyte.

A

Signaling pathway

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5
Q

Lipid droplets contain _______________ ____________, mostly triacylglyerols, and ____________, proteins on the surface of lipid droplets that restrict access to the inner core.

A

Cholesterol esters

Perilipin

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6
Q

Do lipid droplets have a mono- or bilayer of phospholipids?

A

A monolayer

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7
Q

Glucagon and epinephrine in the adipocyte signal the activation of PKA. Regarding fatty acid degradation, PKA phosphorylates and activates ____________, which allows for lipase access to triacylglycerols in lipid droplets, and ____________ ___________ ____________, which hydrolyze triacylglyerols into three fatty acids and glycerol.

A

Perilipin

Hormone sensitive lipases

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8
Q

“Free” fatty acids are carried non-covalently through the blood stream by serum _______________ and transported to target sells.

A

Albumin

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9
Q

Where are fatty acids oxidized?

A

Mitochondrial matrix

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10
Q

What is the first reaction in fatty acid oxidation?

A

Fatty acyl-CoA synthetase

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11
Q

What is the mechanism of fatty acyl-CoA synthetase?

A

Ampylation

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12
Q

What intermediate is produced in the fatty acyl-CoA synthetase mechanism?

A

Fatty acyl-AMP

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13
Q

How does AMP leave the fatty acyl molecule?

A

After nucleophilic attack by CoASH

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14
Q

What is the end product of fatty acyl-CoA synthetase?

A

Fatty acyl-CoA

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15
Q

Where does fatty acyl-CoA synthesis occur?

A

Cytosol

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16
Q

Where is fatty acyl-CoA synthetase located?

A

Outer mitochondrial membrane

17
Q

How many ATPs does fatty acyl-CoA synthetase require?

A

2 ATPs

18
Q

How does fatty acyl-CoA enter the intermembrane space?

A

Via the fatty acyl-CoA porin

19
Q

What happens to fatty acyl-CoA once in the intermembrane space?

A

It is converted to fatty acylcarnitine via the carnitine-palmitoyl transferase I

20
Q

Fatty acyl CoA and ______________ are converted to CoA and _________ ____________ via carnitine palmitoyl transferase I in the intermembrane space.

A

Carnitine

Fatty acylcarnitine

21
Q

How does fatty acylcarnitine enter the mitochondrial matrix?

A

Via the carintine acylcartine translocase

22
Q

The carnitine acylcarnitine translocase is an _____________________, bringing fatty acylcarnitine into the mitochondrial matrix while transporting out of the mitochondrial matrix.

A

Antiporter

23
Q

The carnitine acylcarnitine translocase is a type of ______________ based on concentration gradients.

A

Passive transport

24
Q

What happens to fatty acylcarnitine once it enters the mitochondrial matrix?

A

It is converted to fatty acyl-CoA via carnitine-palmitoyl transferase II

25
Q

Fatty acylcarnitine and CoA are substrates for _________________ _____________ ____________ ____, which converts these products to fatty acyl-CoA, for beta oxidation, and carnitine, which is transported back into the intermembrane space via the carnitine acylcarnitine translocase.

A

Carnitine pamitoyl transferase II

26
Q

What are the enzymes and porins/antiporters involved in the carnitine shuttle system?

A

Fatty acyl-CoA synthetase

Fatty acyl-CoA porin

Carnitine-palmitoyl transferase I

Carintine acylcarintine translocase

Carnitine-pamitoyl transferase II

27
Q

What is the rate-limiting step in the oxidation pathway?

A

Entry of fatty acids into the mitochondria

28
Q

________________ _______________ is an inhibitor of the carnitine palmitoyl transferase I.

A

Malonyl CoA

29
Q

Complete oxidation of fatty acids occurs in three stages. What are they?

A
  1. Beta-oxidation
  2. Acetyl-CoA oxidation to CO2 in CAC
  3. Electron transport and oxidation
30
Q

Beta-oxidation occurs in four steps. What are they?

A
  1. Dehydrogenation of fatty acyl-CoA via acyl-CoA dehydrogenase
  2. Hydration of double bond of trans-delta2-enoyl-CoA catalyzed by enoly-CoA hydratase
  3. Beta-hydroxylacyl-CoA dehydrogenated to form beta-ketoacyl-CoA catalyzed by beta-hydroxyacyl-CoA dehydrogenase
  4. Reaction of beta-ketoacyl-CoA with CoA to give off acetyl-CoA catalyzed by thiolase
31
Q

Acyl-CoA dehydrogenase forms a trans double bond at the ___ position via reduction of ____.

A

Alpha position

FAD

32
Q

Enoyl-CoA hydratase adds a water molecule across the trans double bond with the hydroxyl group positioned at the ___ position.

A

Beta

33
Q

Beta-hydroxylacyl-CoA dehydrogenase oxidizes the hydroxyl group to a ketone via reduction of ____.

A

NAD+

34
Q

Beta-ketoacyl-CoA reacts with CoA to give off CoASH via ______________ in the last step of beta oxidation.

A

Thiolase

35
Q

What is the net yield of one round of beta oxidation?

A

1 FADH2

1 NADH

1 acetyl-CoA

36
Q

What is MCAD deficiency?

A

An autosomal-recessive disorder that reduces an individual’s ability to oxidize fatty acids with 6 to 10 carbons resulting in severe hypoglycemia and hypoketonemia; treatment is to avoid fasting

37
Q

What happens when a fatty acid contains a cis double bond? What is required to bypass this?

A

A general base deprotonates the alpha position and creates an oxyanion

An isomerase catalyzes the restoration of the carbonyl group, which shifts the trans double bond over one and causes the cis double bond to protonate

38
Q

What enzyme catalyzes the conversion of a cis or trans double bond at position 3 to a trans double bond at position 2.

A

Enoly-CoA isomerase

39
Q

A cis delta-4 double bond inhibits enoly-CoA hydratase. What reduces the delta-4 double bond?

A

2,4-dienoyl-CoA reductase

Biochemistry II (19 decks)

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