Cellular respiration

Aerobic cellular respiration

uses oxygen to harvest energy from organic compounds

energy is used to synthesize ATP from ADP and PI

4 stages of aerobic respiration

pyruvate oxidation

citric acid/ kreb’s cycle

electron transport

oxidative phosphorylation

Anaerobic pathways

energy extracted from food molecules

occurs in areas with no oxygen

Fermentation

uses an organic compound as the final oxidizing agent to produce energy

Glycolysis

source of ATP

production of 10 enzymatic reactions in cytosol

Products of glycolysis

2 G3P

4 ATP

2 NADH

Energy investment phase

conversion of glucose into 2 3-C sugars

Energy payoff phase

2 G3P created

Pyruvate oxidation

pyruvate created in glycolysis must pass through both the inner and outer membranes through large pores

Process of pyruvate oxidation

in-between step of glycolysis and kreb’s cycle

pyruvate is converted into an acetyl group and temporarily bonded to sulfur at the end of CoA

results in Acetyl-CoA complex

Steps of pyruvate oxidation

COOH group of pyruvate removed and produces Co2

remaining C molecules are oxidated

dehydrogenation reaction transfers 2 electrons and a proton to NAD+, forming NADH

Citric acid/ kreb’s cycle

8 enzyme-catalzyed reactions

results in oxidation of acetyl groups to Co2

for every 1 ATP produced, 1 FADH2, 3 NADH and 1 acetyl-CoA are produced

Steps of citric acid cycle

2 Acetyl-CoA enter from glycolysis

step 1: acetyl group enters and reacts with oxaloacetate to from citrate

step 3,4,5,6,8: some relased energy is captured to form NADH, ATP and FADH2

steps 3,4,8: NAD+ reduced to form NADH

step 5: ATP from ADP + Pi

Products of the Kreb cycle

each glucose molecule= 2 pyruvate molecules = 2 turns of citric acid cycle

Electron transport chain

occurs on inner mitochondrial membrane in eukaryotes

facilitates transfer of electrons from NADH → FADH2

Electron transport chain protein complexes

1. NADH hydrogenase

2. succinate hydrogenase

3. cytochrome complex

4. cytochrome complex

Electron shuttles in ETC

1. ubiquinone (UQ): hydrophobic, found in core

   shuttles electrons from complex 1→ 3

2. Cytochrome C (Cyt. C): located on inter membrane

   space slide of membrane and transfers electrons from complex 3 → 4

electronegativity of ETC

increasing electronegativity along chain

have cofactors that alternate between reduced and oxidized states

O2 has strongest pull

NADH has weakest pull

Beta-oxidation

process by which fatty acids (saturated) are broken down for use in energy production

occurs in mitochondrial matrix