krebs cycle

Human Biology 3

2006









Aerobic Respiration

Yesterday we learnt

about glycolysis &

fermentation (anaerobic

respiration).

From 1 molecule of

glucose (C6H12O6):

Glycolysis Ethanol Lactic a

fermentation ferment

2 3C 2 2C 2 3C

molecules molecules + molecul

+ 2H2O 2CO2

2 ATP net 2 ATP net 2 ATP n

2 NADH 2 NADH/2 2 NADH

+ +

NAD NAD

Pyruvate Ethanol Lactic a



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Human Biology 3

2006









Glycolysis releases only a

fraction of the energy

contained in the original

glucose molecule.

Aerobic respiration uses

oxygen to harness as

much energy as possible

from glucose in three

phases:









2

Human Biology 3

2006









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Human Biology 3

2006









Mitochondria

Krebs cycle, the electron

transport chain &

oxidative phosphorylation

occur in the mitochondria,

while glycolysis occurs in

the cytoplasm.



Mitochondria are thought

to be simpler organisms

that formed symbiotic

relationships with other

cells. They have their

own double membranes

and DNA.





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Human Biology 3

2006









The Krebs cycle









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Human Biology 3

2006









Firstly, the

pyruvate has

to go from

the

cytoplasm

into the

mitochondria.



The pyruvate passes

through a protein channel

in the mitochondrial

membrane, and then it

gets processed to

produce Acetyl CoA +

CO2 + 1NADH. Acetyl

CoA acts as a carrier for

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Human Biology 3

2006









the 2 carbon molecule as

it enters the Krebs (citric

acid) cycle.









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Human Biology 3

2006









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Human Biology 3

2006









So, our total so far is:

Glucose 2H2O + 6CO2

+ 4ATP









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