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Respiration:
Why do we need it?
• Metabolic reactions
• Active transport
• Secretion - exocytosis
• Endocytosis
• Synthesis of large molecules from smaller ones
• DNA replication
• Movement
• Activation of chemicals

ATP:
P

P

P
Adenine

Ribose

• Phosporylated nucleotide
...

• Can be hydrolysed to ADP and P providing an immediate source of
energy for biological processes in cells in small, manageable
amounts
...

• Continually being hydrolysed and resynthsised
...
Enzymes are not very good at catalysing oxidation and
REDUCTION reactions
...

Delivery of hydrogens to cristae reoxidises so they can ‘pick up’ more
hydrogens
...

• When a molecule has accepted two hydrogen atoms with their
electrons it is REDUCED
...

Coenzyme A:
• Carries ethanoate groups made by pyruvate during link reaction
on to the Krebs cycle
...
PHOSPHORYLATION – One ATP is hydrolysed and the P
Glucose (6C)
1
Hexose Bisphosphate (6C)
2
Triose
phosphate
(3C)

Triose
phosphate
(3C)
3

Intermediate
(3C)
Pyruvate
(3C)

4

Intermediate
(3C)
Pyruvate
(3C)

Group attaches to glucose to fructose
...

2
...

3
...
Dehydrogenase
enzymes are involved and 2 ATP
are formed
...
CONVERSION – triose phosphate
is converted to pyruvate
...
Has:
• Enzymes that catalyse the stages of these reactions
• Molecules of coenzyme NAD

• Oxaloacetate – the 4 carbon compound that accepts acetate from
the link reaction
...

• Mitochondrial ribosomes where proteins are assembled
...


Inner Membrane –
• Impermeable to most small ions, including protons which accumulate
in the IMS to form a proton gradient
...

• Embedded with many electron carriers and ATP synthase
...
Each is associated with a
cofactor
...
Haem groups that
contain iron
...

• They are oxidoreductase enzymes as they are involved in
oxidation and reduction reactions
...

• Because iner membrane is impermeable protons accumulate in
IMS, building up proton gradient
...

• Also known as stalked particles
...

Protons flow down a proton gradient, through the ATP synthase
enzymes, from the IMS in to the matrix
...
The force of the flow drives the rotation of part of
the enzyme and allows ADP and P to be joined to make ATP
...
H atoms pass back in to matrix
...

• Enzyme pyruvate decarboxylase removes carboxyl group from
pyruvate
...


6
...


Reduced
NAD

Reduced
NAD
4C compound

5C compound

5
...


4C compound

Reduced FAD
ATP
4
...
Acetate is offloaded from CoA and joins with oxaloacetate to
form citrate
...
Citrate decarboxylated and dehydrogenated
...

3
...

4
...
During
which an ADP is phosphorylated to ATP
...
Second 4C is changed to another 4C
...

6
...
Another NAD is reduced

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