Cellular Respiration

Tags

Biology

Cegep/1

Word count

248 words

Reading time

2 minutes

Combustion of glucose to produce ATP
Redox

$C_6{H}_{12}{O}_6$ (glucose) + 6 $O_2$ -> 6 $C{O}_2$ + 6 $H_{2}O$ + 30-32 ATP + heat

Most energy is actually released as heat.

Variation of ATP yield is due to energy loss and proton leakage during chemiosmosis.

Steps

Throughout glycolysis, pyruvate oxidation and Krebs cycle, glucose is oxidized and electron carriers (${\mathrm{NAD}}^{+}$ and $\mathrm{FAD}$) are reduced. They then transport the electrons to the ETC.

Glycolysis

Glucose -> 2 Pyruvate + 2 $\mathrm{NADH}$ + 2 ATP
Substrate-level phosphorylation

In cytosol

Phases:

1. Energy investment phase: glucose + 2 ATP -> 2 G3P
2. Energy payoff phase: 2 G3P -> 2 Pyruvate + 2 $\mathrm{NADH}$ + 4 ATP

Pyruvate oxidation

2 Pyruvate -> 2 Acetyl-CoA + 2 $\mathrm{NADH}$ + 2 ${\mathrm{CO}}_2$

In mitochondria

Krebs cycle

2 Acetyl-CoA -> 6 $\mathrm{NADH}$ + 2 ${\mathrm{FADH}}_2$ + 2 ATP + 4 ${\mathrm{CO}}_2$
Substrate-level phosphorylation
A.k.a. citric acid cycle

In mitochondria

Electron transport & chemiosmosis

10 $\mathrm{NADH}$ + 2 ${\mathrm{FADH}}_2$ + 6 ${\mathrm{O}}_2$ -> 6 ${\mathrm{H}}_2\mathrm{O}$ + 26-28 ATP
Oxidative phosphorylation

In mitochondria
Makes most of the ATP

Steps:

1. Complex I / II transfers electrons from $\mathrm{NADH}$ / ${\mathrm{FADH}}_2$ to ETC.
2. Electrons flow through ETC and gives energy to complexes I, III and IV to pump protons to the intermembrane space to generate a proton gradient.
3. Protons flow through ATP synthase into the matrix, powering phosphorylation.

Contributors

Ajitani Hifumi

Changelog

Last edited about 2 hours ago

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