Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry Block 2 > Fatty Acid Oxidation > Flashcards

Fatty Acid Oxidation Flashcards

1
Q

What is happening big picture in beta oxidation

A

Going from storage situation to breaking down fatty acids for mobilization for energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What kind of fatty acids are the major fuel store for the body

A

TAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What two enzymes releases fatty acids from TAG (from adipose)

Which one is more important

Main difference in why this is the case?

A

Adipose lipoase and hormone sensitive lipase

Hormone sensitive lipase

HSL cannot be re-esterified (more set in stone); adipose lipase can be re-esterified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What activates HSL

A

Epinephrine and glucagon (because it is specifically activated by cAMP dependent protein kinases - think cell signaling lecture)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

~What does lipoprotein lipase do

A

Releases FAs from TAG in circulating lipoproteins to FFAs and glycerol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When HSL is activated, what does it bind to

A

Perilipin (lipid droplet surface protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When HSL is activated, what does it do

A

It helps with the phosphorylation of ACC in order to inactivate it and turn off fatty acid synthesis

~side note: insulin will do opposite; dephosphorylate HSL to make it inactivate and activate ACC when fatty acid synthesis needs to happen again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When TAG is degraded, where does the glycerol from it go?

A

Has to go to liver, not adipose because liver has glycerol kinase and adipose does not. (Adipose cannot do anything with glycerol once it is removed from FAs and not in TAG form)

~TAG= glycerol + FAs~

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens to glycerol when it is brought to the liver

A

1 of 2 things:

Phosphorylated in the liver to be used for TAG synthesis

Reversibly converted to DHAP (by glyercol phosphate dehydrogenase); DHAP can participate in glycolysis or gluconeogenesis

(In between meals - goes to glycolysis; deep into fasting - goes to gluconeogenesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What two organs do not use fatty acids for energy

A

RBCs (no mitochondria) and brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

About half the the FFAs released from adipose TAG are re-esterified to?

Clinical significance?

A

Glycerol-3-phosphate

Decreases plasma FFA associated with insulin resistance in type 2 diabetes and obesity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

3 products of beta oxidation

A

Acetyl CoA, NADH, FADH2

~NADH and FADH2 can feed right into ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does our body obtain carnitine (2 ways)

A

Diet: mostly meat products
Synthesized: in liver/kidney only using lysine and methionine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where is majority of carnitine housed in the body?

A

Skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Carnitine deficiency would affect what?

A

The ability of tissues to use LCFA as a metabolic fuel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Secondary carnitine deficiencies are caused by

A

Decreased synthesis due to liver disease, dietary malnutrition, hemodialysis, or conditions where your body needs more carnitine (pregnancy, infections, burns, trauma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Primary carnitine deficiencies are caused by congenital deficiencies in what two things?

A

Renal tubular reabsorption of carnitine; or carnitine uptake by cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

CAT1 genetic defect?

A

Decreased liver use of LCFA during a fast (severe hypoglycemia, coma, death)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

CAT II genetic defect?

A

Heart and skeletal muscle exhibit the symptoms following prolonged exercise (cardiomyopathy, muscle weakness, myoglobinemia)

20
Q

Treatment for both CAT I and II deficiencies

A

Avoid fasting, eat high carbs and low LCFA, supplement with carnitine and medium chain fatty acids

21
Q

Short/medium chain fatty acids do not need CAT 1 or 2. How do they get converted?

A

Thiokinase (so malonyl CoA has no effect because you don’t need CAT1)

22
Q

How is beta oxidation linked to gluconeogenesis

A

Acetyl CoA is a positive allosteric effector of pyruvate carboxylase

23
Q

How many ATPs are produced from beta oxidation

A

129 ATP

24
Q

What is different about beta oxidation of an odd number carbon fatty acid chain?

A

Similar except the final cleavage produces a 3 carbon product: propionyl CoA (not acetyl CoA)

25
Q

3 steps for metabolism of propionyl CoA

A
  1. Propionyl CoA is carboxylated by propionyl CoA carboxylase (ABC enzyme*)
  2. D methylmalonyl CoA -> L methylmalonyl CoA (isomerization)
  3. Carbons from L-methylmalonyl CoA are rearranged to form succinyl CoA by methylmalonyl CoA mutase to enter TCA
26
Q

Which two enzymes from the last slide (metabolism of propionyl CoA) require vitamin B12

So vitamin B12 deficiency leads to?

A

Propionyl CoA carboxylase and methylmalonyl CoA mutase

Metabolic acidosis and potential mental retardation

27
Q

Difference in beta oxidation of saturated vs unsaturated fatty acids

A

Unsaturated release less energy

Mono and poly require additional enzymes for complete oxidation

28
Q

Where are very long chain fatty acids beta oxidized?

A

Peroxisomes (does not generate ATP)

29
Q
  1. Zellweger syndrome?
  2. X linked adrenoleukodystrophy?
  3. Both disorders lead to?
A
  1. Failure to deliver correct enzymes to peroxisomes
  2. Cannot transport VLCFA across the peroxisome membrane
  3. Accumulation of VLCFAs in the blood/tissue
30
Q

Difference between alpha and beta oxidation

A

Alpha: acyl CoA dehydrogenase cannot work on the substrate so alpha oxidation uses PhyH instead

31
Q

What disease is caused by PhyH deficiency?

A

Refsum (rare) symptoms are mostly neurologic - treat with dietary restrictions

32
Q
  1. What is MCAD
  2. Symptoms
  3. Treatment
A
  1. Deficiency in fatty acyl CoA dehydrogenase
  2. Severe hypoglycemia
  3. Avoid fasting
33
Q

Where are ketone bodies formed?

A

Liver mitochondria

34
Q

3 metabolic products of ketone bodies

A

Acetoacetate, 3-hydroxybutyrate, and acetone (acetone is dead end product)

35
Q

When would liver produce ketones?

A

When acetyl CoA levels are higher than oxidation capacity

36
Q

What part of body mainly uses ketones?

A

Skeletal muscles (RBCs cannot use ketones- no mitochondria)

37
Q

What two symptoms would you get if you had a disorder in being able to do fatty acid oxidation

A
  1. Hypoketosis - due to decreased acetyl CoA availability

2. Hypoglycemia- due to increased reliance on glucose for energy

38
Q

If you have high hepatic acetyl CoA, what enzyme will get inhibited and what enzyme will get activated?

A

Inhibited: pyruvate dehydrogenase

Activated: pyruvate carboxylase

39
Q

Pyruvate carboxylase produces __ which is used in what pathway?

A

OAA - gluconeogenesis also for ketone body synthesis

40
Q

How does OAA get shifted to do ketogenesis opposed to gluconeogenesis?

A

Beta oxidation leads to acetyl CoA, NADH, and FADH2. Acetyl CoA leads to formation of OAA and increased levels of NADH lead OAA to be converted to Malate.

Formation of malate is what shifts acetyl CoA from gluconeogenesis and form ketogenesis

41
Q

What is the rate limiting step in ketogenesis? Where is this enzyme present?

A

HMG CoA synthase - present in the liver in significant amounts

42
Q

Main takeaway from steps of ketogenesis

A

HMG CoA is substrate for producing acetoacetate (ketones)

HMG CoA was produced from reverse of thiokinase reaction in beta oxidation

43
Q

Ketolysis: using ketone bodies

  1. 3-hydroxybutyrate is oxidized to acetoacetate and this produces?
  2. Next 2 steps?
A
  1. NADH in peripheral tissues

2. Acetoacetate takes CoA from succinyl CoA; acetoacetyl CoA is converted to 2 acetyl CoA

44
Q

Why can’t liver use ketone bodies as fuel?

A

Liver lacks thiphorase

45
Q

Why does ketonemia and ketouria happen in uncontrolled type I diabetes?

A

Body thinks you are starving because insulin is not being produced so ketone bodies are made. But since there is actually glucose in the blood the ketone bodies produced are not used so they build up

46
Q

Diabetic ketoacidosis causes?

A

Fruity smelling breath from acetone, increased secretion of water and dehydration, lower blood pH (ketones are acidic)

Biochemistry Block 2 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions