Lipids 2 Flashcards

1
Q

In the beta oxidation pathway, how many fatty acid carbons does it break down at a time?

A

2

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2
Q

What are the products of beta oxidation?

A

Acetyl CoA, NADH, and FADH2 all sources of energy for ATP

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3
Q

Where does beta oxidation occur?

A

In the mitochondrial matrix

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4
Q

What does FA released from an adipocyte bind to?

A

Albumen

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5
Q

What are the 3 stages of beta oxidation?

A

Activation, transport and degradation

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6
Q

How is the fatty acid activated?

A

It is involved in a reaction using ATP to form fatty acyl co a in the CYTOPLASM (of the target tissue)

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7
Q

How does the fatty acyl co a cross the mitochondrial walls?

A

Fatty acyl co a diffuses across the first membrane. The carnitine shuttle is responsible for the movement of the fatty acyl co a across the second membrane- Co a component of the molecule is removed, remaining molecule then binds to carnitine and passes over the membrane with help from translocase. Carnitine is removed and fatty acyl co a is reformed

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8
Q

What is the effect of malonyl co a?

A

Inhibits the transferase enzymes, preventing further degradation of the fatty acid. Malonyl is needed for FA synthesis - therefore prevent the synthesis and degradation happening at the same time.

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9
Q

What is the effect of carnitine fatty acyl tranferase or carnitine palmitoyl transferase deficiency?

A

No beta oxidation
Hypoglycemia (low suga)

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10
Q

What are the steps of degradation?

A

Dehydrogenation - produces FADH2
Hydration - Requires H20
Dehydrogenation- To produce NADH
Thyolysis- Cleaved to produce acetyl co a

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11
Q

What is the precursor of FADH2 and NADH

A

FADH2 = FAD
NADH = NAD+

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12
Q

What happens to acetyl co a produced?

A

Joins TCA cycle (citric acid cycle)

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13
Q

What carbon products are produced after every beta oxidation cycle?

A

A carbon species two carbons shorter than the original + acetyl co a

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14
Q

How much ATP does each of the following molecules give / use?
FADH2
NADH
Acetyl Co A

A

FADH2 = 2 ATP /1.5
NADH = 3 ATP/2.5
Acetyl Co a = 12 ATP
Ketone= 22 ATp

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15
Q

Where does a preliminary beta oxidation of very long fatty acids take place?

A

Peroxisomes

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16
Q

Why is the first step (dehydrogenation) less energy efficient?

A

No FADH2 is produced

17
Q

What happens to the FA linked to the carnitine?

A

Diffuses from peroxisome to mitochondria for further oxidation

18
Q

What happens to acetyl co a levels during fasting / starvation?

A

Liver flooded with acetyl co a

19
Q

What is the effect of high acetyl co a levels on pyruvate dehydrogenase?

A

Pyruvate dehydrogenase is inhibited reducing further acetyl co a formation?

20
Q

What is the effect of high acetyl co a levels on pyruvate carboxylase?

A

Activates pyruvate carboxylase and therefore increases the oxaloacetate present

21
Q

What does the amount of ketogenesis depend on?

A

The amount of acetyl co a, excess is converted into ketone bodies

22
Q

What muscles use ketone bodies as an energy source?

A

The skeletal muscles, and the cardiac muscles

23
Q

What important organ can ketone bodies also provide energy for?

A

The brain

24
Q

Where are ketone bodies formed?

A

The liver, although the liver cannot actually use them!

25
Q

How are ketone bodies transported from the liver?

A

In the blood to other tissues, they are soluble and do not need albumen or lipoprotein

26
Q

What can lead to very high levels of ketone bodies in the blood?

A

Starvation or uncontrolled diabetes

27
Q

What can result from a higher build to use ratio of etone bodies?

A

Ketonemia, ketonuria and acidosis
fruity breath odour due to acetone