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Molecular Biology 2 > Oxidation Pathways > Flashcards

Oxidation Pathways Flashcards

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1
Q

What are the stages of fatty acid or beta oxidation?

A
  1. Transport - fatty acids from blood to cytoplasm
  2. Trapping fatty acids in the cytoplasm
  3. Transporting fatty acids into the mitochondria
  4. Stripping h/e out to make acetyl CoA
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2
Q

How do fatty acids exist in the bloodstream?

A

Loosely associated with albumin.

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3
Q

What is meant by the amphiphilic nature of fatty acid molecules? What does this mean for transport in the blood?

A

Had hydrophilic and hydrophobic parts. Bound to albumin so it doesn’t act like a detergent in the blood.

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4
Q

How does transport from the blood to the cytoplasm occur of fatty acids?

A

Mostly passive.

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5
Q

What are fatty acid molecules associated within the cytoplasm?

A

Fatty acid binding proteins.

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6
Q

What is linked to fatty acid to trap the molecules inside the cytoplasm?

A

Coenzyme A. It is always attached to CoA from this point onwards.

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7
Q

What activates the fatty acid inside the cytoplasm?

A

Attachment to CoA

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8
Q

What are the energy requirements of activating fatty acids by turning them into FA-CoA?

A

High - ATP converted to AMP and pyrophosphate is hydrolysed.

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9
Q

What is CoA? What is involved in its form?

A

A large charged molecule. (Card 5 for form).

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10
Q

How does the transport of fatty acids to the mitochondria occur?

A

React the fatty acid CoA with carnitine to make fatty acylcarnitine which can be transported across the mitochondrial membrane to the matrix. (Carnitine acyl-transferases)

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11
Q

Once inside the mitochondria what happens to the FA?

A

The opposite to how it got in - carnitine goes back to the cytoplasm.

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12
Q

What occurs in the first H/e- stripping step of fatty acid oxidation?

A

FAD rips hydrogens out of CH2CH2 links and forms a double bond between beta and alpha carbon atoms. This is hydrated to give rise to an OH group at the beta position.

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13
Q

How is the first H/e- stripping step of fatty acid oxidation catalysed?

A

By a dehydrogenase that uses FAD (acyl-CoA dehydrogenase).

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14
Q

What occurs in the second H/e stripping step of fatty acid oxidation?

A

NAD stips from the OH group. Rips out hydrogens and electrons from the alcoholic group and turns it into a keto group. The keto carbon is attacked by CoA and get acetyl-CoA - comes off the original chain and leaves a 14 carbon acyl CoA.

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15
Q

Glycolysis occurs in the ______.

A

Cytoplasm.

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16
Q

What is the purpose of glycolysis? ie what does it bridge?

A

Forms bridge between the processing of glucose from the blood and endogenous glycogen to provide acetyl CoA for Krebs cycle or lactate to be recycled by the liver.

17
Q

What is the first step of glycolysis?

A

Glucose uptake by the glucose transporters?

18
Q

What are the glucose transporters and where are they located?

A

GLUT 1 - present in all cells at all times
GLUT 4 - live in golgi apparatus and come out during exercise or stimulated by insulin (muscle and adipose tissue)
GLUT 2 - in liver and pancreas

19
Q

What happens to glucose when it moves from the blood into the cytoplasm?

A

Hexokinase using ATP transforms glucose into glucose 6-phosphate.

20
Q

What is the preparatory phase of glycolysis?

A

Phosphorylation and trapping. Further phosphorylation to a molecule that can be phosphorylated in the 1 and 6 positions (ATP used).

21
Q

What are we left with at the end of the preparatory phase of glycolysis?

A

A symmetrical molecule that is ready to liberate energy and split in two at the end of the phase to produce 2 3-carbon molecules. (Card 6)

22
Q

What occurs in the first step of phase 2 of glycolysis?

A

Use of NAD to give NADH and convert it to energy-dense molecule which is primed for direct phosphorylation of ADP.

23
Q

What occurs in the second step of phase 2 of glycolysis?

A

1,3-bisphosphoglycerate phosphorylates ADP to ATP at the substrate level.

24
Q

What occurs in the third step of phase 2 of glycolysis?

A

The 3 carbon molecules made in phase 1 are rearranged to make phosphoenolpyruvate - make ATP and lose phosphate to make pyruvate. Happens twice for every molecule of glucose (2 3-carbon). Card 6

25
Q

What do we have at the end of glycolysis?

A

2 ATP per glucose, 2 pyruvates and two NADH

26
Q

How do we complete glycolysis?

A

Pyruvate undergoes oxidation either aerobic or anaerobic.

27
Q

How does oxidation of pyruvate occur?

A

Transport into mitochondria and oxidised with pyruvate dehydrogenase.

28
Q

How do we maintain the supply of NAD?

A

Peroxide NADH - leads to lactate production.

29
Q

The Krebs cycle occurs in the ________.

A

Mitochondria

30
Q

What is the role of the Krebs cycle?

A

NOT to produce ATP but produce NADH and FADH2 for the electron transport chain.

31
Q

What else (not nadh or fadh2) is generated in the Krebs cycle and how ?

A

Acetyl CoA oxidise all acetate carbons to carbon dioxide. CO2.

32
Q

Oxaloacetate is a ____ carbon molecule that is converted to _____ using _________.

A
  1. Citrate (6C) using acetyl CoA.
33
Q

Citrate in the Krebs cycle undergoes_______?

A

Two oxidation steps that result in the formation of carbon dioxide.

34
Q

After the two carbon dioxides are made from the oxidation steps in the Krebs cycle what happens?

A

The rest of the steps are used to synthesise oxaloacetate so the reaction can go again. (Card 7)

35
Q

Provide an overview of exactly what is generated in the citric acid cycle.

A

(Card 7)

36
Q

How are the beta oxidation pathways regulated?

A

Mainly by availability of co-factors NAD, FAD and ADP and inhibited by high energy change (ATP:ADP)

Molecular Biology 2 (13 decks)

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