4 metabolic pathways for cellular respiration
(Aerobic respiration)
2-Breakdown of
pyrvate.
Yield: 1 NADH for each pyruvate
3-Citric acid cycle
Yield: 1 ATP + 3 NADH + 1FADH2
4-Oxidative
phosphorylation (requires oxygen)
1-Glycolysis
Yield: 2 ATP
Energy investment
cleavage
Energy liberation
step 1-3
-2 ATP hydrolyzed to create fructose-1,6 bisphosphate
steps 4-5
-6 carbon molecules broken into two 3 carbon molecules of glyceraldehyde-3-phosphate.
-
- steps 6-10
-two glyceraldehyde-3-phosphate molecules broken down into two pyruvate molecules- produces 2 NADH and 4ATP
In eukaryotes, pyruvate is transported into the mitochondrial matrix.
Pyruvate is made in the cytosol by glycolysis. It travels through a channel in the outer membrane and an H+ inner membrane to reach the mitochondrial matrix.
CO2 and NADH is made.
During this process, the acetyl group is transferred to coenzyme A (CoA) and is later removed and enters the citric acid cycle.
Pyruvate is oxidized via pyruvate dehydrogenase to an acetyl group and
Metabolic cycle:
- Some molecules enter while others leave.
- Series of organic molecules regenerated in each cycle.
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1- Acetyl is removed from Acetyl CoA and attached to oxaloacetate to form citrate (aka citric acid).
2- Series of steps releases 2 CO2, 1 ATP, 3 NADH, and 1 FADH2.
3- Oxaloacetate is regenerated to start the cycle again.
Phosphorylation occurs by ATP synthase
Oxidative process involves electron transport chain.(ETC)
Produces a H+ electrochemical gradient.
Anaerobic Respiration and
Fermentation
(The two strategies used by cells in anaerobic conditions)
Produce ATP only via substrate-level phosphorylation.
Fermentation: is the breakdown of organic molecules without net oxidation.
- Uses glycolysis to produce ATP.
- Glycolysis uses up NAD+ and makes too much NADH under anaerobic conditions (dangerous situation).
1- Muscle cells solve problem by reducing pyruvate into lactate.
2- Yeast solve problem by making ethanol.
Use substance other than 02 as final electron acceptor in electron transport chain.
E.coli uses nitrate (NO3-) under anaerobic conditions.
Also makes ATP via chemiosmosis even under anaerobic conditions