Respiration

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RESPIRATION

1) Glycolysis-

The first stage of respiration happens in the cytoplasm

6 carbon glucose is broken down into two lots of 3 carbon pyruvic acid

2 ATP is used to start the reaction and 4 ATP is gained making the net gain 2 ATP

Hydrogen is produced which combines with NAD to make NADH

2) The Krebs Cycle

The second stage of respiration happens in the matrix of the mitochondria and requires oxygen

Pyruvic acid is broken down into a 2 carbon acetyl group which is broken down into 2 carbon acetyl co-A

Acetyl co-A breaks down into 6 carbon citric acid

At each stage after this a hydrogen and a carbon is released until the compound has 4 carbons

Every hydrogen combines with NAD to form NADH

The 4 carbon compound combines with acetyl co-A to make citric acid and the cycle starts again

3) The Cytochrome System

The third stage of respiration happens on the cristae of the mitochondria and requires oxygen to be the final hydrogen acceptor

The NADH from the previous stages of respiration come to the cytochrome system and release hydrogen

The hydrogen moves along the hydrogen carriers and produces 36 ATP

The hydrogen that leaves the cytochrome system is accepted by oxygen to make h2o (water)

IF THERE IS NO OXYGEN:

In animals- Lactic acid is produced until the oxygen debt is repaid and the Krebs Cycle can continue

In plants- Ethanol and co2 is produced wich can't be reversed

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