Cellular respiration: Part 2 Kreb Cycle

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Cellular respiration: Part 2 Kreb Cycle

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intermembranespace inner

membrane

outermembrane

matrixcristae

Mitochondria — Structure Double membrane energy harvesting

organelle

mitochondrialDNA

What cells would have a lot of mitochondria?

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Mitochondria – Function

What does this tell us about the evolution of eukaryotes?

Dividing mitochondriaWho else divides like that?

Advantage of highly folded inner membrane?

Membrane-bound proteinsEnzymes & permeases

Oooooh!Form fits function!

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Pyruvate oxidized to Acetyl CoA

reduction

oxidation

Coenzyme APyruvate

Acetyl CoA

C-C-C C-CCO2

NAD+

Acetyl CoA enters Krebs cycle

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Citric Acid cycle aka Krebs Cycle

in mitochondrial matrix 8 step pathway

Evolved later than glycolysis does that make evolutionary sense?

bacteria 3.5 billion years ago (glycolysis) free O2 2.7 billion years ago (photosynthesis) eukaryotes 1.5 billion years ago (aerobic

respiration = organelles mitochondria)

1937 | 1953

Hans Krebs1900-1981

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Whassup?

What’s the point?

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Energy accounting of Citric Acid cycle

1 ADP 1 ATPATP

2x

4 NAD + 1 FAD 4 NADH + 1 FADH2

pyruvate CO2

3C 3x 1C

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How is the CAC thermodynamically favoured?

1st Law: Energy is not created or destroyed

2nd Law: There is an increase in entropy in the universe

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Value of Citric Acid cycle? If the yield is only 2 ATP then how was

the Citric Acid cycle an adaptation?

like $$in the bank

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2 Methods of Generating ATP

Substrate Level Phosphorylation

Chemiosmotic Generation of ATP

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Substrate Level Phosphorylation

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Substrate Level Phosphorylation

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Chemiosmosis

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OXIDATIVE PHOSPHORYLATION

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NAD+ H+

Q

e-e-

H+ H+

e-e-C

H+ H+

e-e-

0 + 2H+ = H2O

H+ H+

ADP + Pi ATP

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FADH2 modification

NADH + H+

NAD+

oxidation

reduction

FADH2 FAD+

ADP + Pi ATP

QH2

½ O2 H2O

Q oxidizedcytochrome c

Cytochrome coxidase

NADH-Qreductase

ATPsynthase

Cytochrome b, c1

H+

H+

Succinate Qreductase