Glycolysis 1

Glycolysis 1

Lecture 22Pages 427-439

With or without O2

• Early Earth had no oxygen

• Just a form of glycolysis existed before that time

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ATP & Heat• Three key food types - sugars, fats, &

proteins• Three stage breakdown -

1) Digestion - reduces large polymers to subunits - sugars, fatty acids & glycerol, and amino acids1) outside cells - gut2) inside cells in lysozymes

2) Oxidative Breakdown GLYCOLYSIS - cytosol and mitrochondria

3) Complete oxidation - within mitrochondria

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A typical cell has about a billion ATP molecules at one time. These are used and regenerated with a minute or two!

GLYCOLYSIS - No oxygen needed for this 10 step phase

Net result is the formation of just two ATP molecules & also two molecules of NADH

Without Oxygen…

FERMENTATION -

Without oxygen - there is really only fermentation.

Two main types -1) Generation of lactate

- as in muscle cels running without oxygen. The lactate is excreted from the cell…

The alternative, as seen here, is the formation of ethanol. Both take place in the cytosol.

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With Oxygen…

• The pyruvate generated by glycolysis is rapidly degraded to yield lots of energy and CO2

• Oxygen is eventually needed for the process to continue

• CITRIC ACID CYCLE

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