Link Reaction and Krebs cycle Flashcards

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1
Q

Why do pyruvate need to go through Kreb and Link Reaction?

A

Pyruvate molecules produced during glycosis possess potential energy that can only be released in Kreb cycle

Before entering Kreb’s cycle, pyruvate molecules must be oxidised in procedure called Link Reaction

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2
Q

Where do both link and kreb cycle occur in?

A

Exclusively inside the mitochondria

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3
Q

What happens in link reaction?

A

Pyruvate molecules produced in cytoplasm during glycosis are actively transported into the matrix of the mitochondria

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4
Q

What are the following changes in the link reaction?

A
  • The pyruvate is oxidised to acetate. In this reaction the 3-carbon pyruvate loses a carbon dioxide and two hydrogen,
  • these hydrogen are accepted by NAD to form reduced NAD which is later used to produce ATP
  • 2-carbon acetate combines with molecule called coenzyme A(CoA) to produce a compound called acetlycoenzyme A
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5
Q

Summarised equation for Link reaction:

A

pyruvate + NAD + CoA -> acetly CoA + reduced NAD + CO2

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6
Q

Key facts about link reaction

A
  • Pyruvate is dehydrogenated and decarboxlyated to form acetate
  • Martix of mitocondria
  • Acetate combine with conenzyme A to form acetly coenzyme A
  • Products 1 x CO2, 1X NADH
  • Per glucose - 2 x CO2 , 2 X NADH
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7
Q

Diagram of Link Reaction

A
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8
Q

What does dehydrogenisation mean?

A

Loss of hydrogen atom/ion

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9
Q

What does decarboxlyation mean?

A

Loss of carbon atom

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10
Q

Key facts about Kreb’s cycle

A
  1. 2 carbon acetlycoenzyme A from link reaction combines with 4-carbon molecule to produce 6-carbon molecule to produce 6-carbon molecule
  2. In series of reaction this 6-carbon molecule loses carbon dioxide and hydrogen to give 4-carbon molecule and a single ATP molecule produced as a result of substrate level phosporylation
  3. This 4-carbon molecule combine newmolecule of acetlycoenzyme A to start cycle again
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11
Q

Diagram of Kreb’s cycle

A
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12
Q

Net Gain of Kreb’s cycle

A

1 turn

2x CO2

3x NADH

1 x FADH

1 x ATP

2 tunrs: 4 CO2 , 6 X ReducedNADH , 2 x FADH and 2 ATP

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13
Q

What are coenzymes?

A
  • NAD - respiration
  • FAD- Krebs cycle
  • NADP - Photosynthesis
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14
Q

Why does Kreb cycle important?

A
  • It breaks down marcomolecules into smaller ones- pyruvate is broken down into carbon dioxide
  • It produces hydrogen atoms that carried by NAD to electron transfer chain and provide energy for oxidative phosphorylation this leads to ATPproduction
  • It regenerates 4-carbon molecule that combines with acetlycoenzyme A
  • Sourceof intermediate compounds used by cells to manfacture omportant substances lik fatty acids
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