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ME2019 PART 1 > Lipids 2 > Flashcards

Lipids 2 Flashcards

1
Q

Can fatty acids be converted to glucose?

A

No because pyruvate to acetyl conenzyme A is irreversible

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2
Q

What does the beta-oxidation pathway do?

A

Degrades fatty acids two carbons at a time, producing acetyl coenzyme A, NADH and FADH2

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3
Q

Where does beta-oxidation occur?

A

Mitochondiral matrix

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4
Q
A
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5
Q

Why can red blood cells not perform beta-oxidation?

A

They have no mitochondria

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6
Q

What are the 3 stages of beta-oxidation?

A
  1. Activation of fatty acid in cytosol
  2. Transport into the mitochondria
  3. Degradation to two carbon as acetyl coenzyme A
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7
Q

What do fatty acids form when they are activated?

A

Fatty acyl coenzyme A

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8
Q

Where does the activation of fatty acids occur?

A

The cytosol

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9
Q

What does the reaction of the activation of a fatty acid looking like?

A
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10
Q

Can fatty acyl coenzyme A pass the membrane without help?

A

No, it needs to use the carmitine shuttle

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11
Q

What is the process of the carnitine shutle?

A
  1. Carnitine reacts with acyl coenzyme A to produce acyl carnitine which crosses the mitochondrial membrane
  2. Inside the mitochondria acyl carnitine reactions with coenymze A to produce acyl conenzyme A
  3. Carnitine crosses the membrane and returns to the cytosol to be used again
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12
Q

What does the carnitine shuttle look like?

A
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13
Q

What enzymes are used in the carnitine shuttle?

A

Carnitine palmityl transferase I and II

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14
Q

What can inhibit carnitine polmityl transerase?

A

Malonyl coenzyme A when their is enough broken down fatty acids

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15
Q

What does malonyl coenzyme A ensure?

A

That synthesis and degradation do not happen at the same time

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16
Q

Where does carnitine come from?

A

The diet

Made from lysine or methionine

17
Q

What does carnitine palmitoyl transferase dificiency lead to?

A

No beta-oxidation (hypoglycemia)

Coma

18
Q

What is the treatment of carnitine palmitoyl transferase difficiency?

A

Eating medium and short chain fatty acids that do not require the carnintine shuttle

19
Q

What are the stages of the degradation of beta-oxidation occurs in four stages?

A
  1. Dehydrogenation to produce FADH2
  2. Hydration
  3. Dehydrogenation to produce NADH
  4. Thiolysis (cleaved) to produce acetyl coenzyme A
20
Q

What does each beta-oxidation cycle produce?

A

1 acetyl coenzyme A

Spieces of carbon 2 carbons shorter than the original

21
Q

What would 7 beta-oxidation pathways produce?

A

8 acetyl coenzyme A

7 NADH

7 FADH2

22
Q

What is the total net energy yield of beta-oxidation?

A

129 ATP molecules

23
Q

What do very long chain fatty acids (>22 carbons) need to undergo before beta-oxidation?

A

Preliminary beta-oxidation in peroxisomes

24
Q

How are very long chain fatty acids (>22 carbons) degraded?

A
  1. Preliminary beta-oxidation in peroxisomes, does not produce FADH2 so not as efficient as shorter chains
  2. Shortened fatty acid links to carntine and diffuses into the mitochondria for beta-oxidation
25
Q

Why are very long chain fatty acids not as efficient as shorter ones?

A

Preliminary beta-oxidation in peroxisomes does not produce FADH2

26
Q

What happens during starving/fasting?

A
  1. Liver flooded with acetyl coenzyme A
  2. Acetyl coenzyme A inhibits pyruvate dehydrogenase (pyruvate to acetyl coenzyme A) and activates pyruvate carboxylase (pyruvate to oxaloacetate)
  3. Oxaloacetate is used to produce glucose for gluconeogenesis
27
Q

What happens to excess acetyl coenzyme A during fasting?

A

Converted into ketone bodies

28
Q

What tissues can use ketones for fuel?

A

Cardiac and skeletal muscle

29
Q

When can brain cells use ketones for fuel?

A

During starvation

30
Q

Where are ketone bodies made?

A

In the liver (mitochondrial matrix) and then transported in the blood to other tissues

31
Q

What cannot use ketones for energy?

A

The liver

32
Q

What cannot use fatty acids for energy?

A

The brain

33
Q

Why do ketones not need albumin or lipoprotein to transport in the blood?

A

They are soluble

34
Q

What leads to high ketone concentration?

A

Uncontrolled diabetes or starvation

35
Q

What happens when the rate of ketone production becomes greater than the rate they are used?

A

Body becomes acid (ketosis) which causes a fruity oddur in breath due to acetone

36
Q

What ensure that fatty acid synthesis and degradation do not happen at the same time?

A

Inhibition and the two happening in different places

ME2019 PART 1 (55 decks)

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