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Why do we need to Respire?
Energy: the ability to do work

ATP: a phosphorylated nucleotide and is the universal energy currency

Anabolic Reactions: biochemical reactions where large molecules are synthesised from smaller ones

Catabolic Reactions: reactions where larger molecules are hydrolysed to produce smaller molecules

Metabolic processes that require…

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ATP is a phosphorylated nucleotide. It is a high energy intermediate compound. Each molecule consists of adenosine plus three phosphate

During glycolysis, Krebs and link reaction hydrogen atoms are removed from substrate molecules in Oxidation reactions. These reactions are
catalysed by dehydrogenase enzymes however coenzymes are needed to…

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Stage 1 Phosphorylation

One ATP is hydrolysed and the phosphate group released is attached to glucose at carbon 6
Another ATP is hydrolysed and the phosphate group released is attached to fructose6p at carbon 1 (now called Fructose 1,6
The energy from the hydrolysed ATP activates the hexose sugar…

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Convert each triose phosphate molecule to a molecule of pyruvate

In the process, another 2 molecules of ADP are phosphorylated to 2 molecules of ATP (by substratelevel phosphorylation)

Products of Glycolysis

The Link Reaction
This reaction converts pyruvate to acetate. NAD is reduced.

The Krebs Cycle

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5 The second 4C compound is changed into another 4C compound. A pair of hydrogen atoms are removed and accepted by
Coenzyme FAD, which becomes reduced
6 The third 4C compound is further dehydrogenated and regenerates Oxaloacetate. Another molecule of NAD is reduced.

Product per molecule of glucose Link Reaction…

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The first electron carrier to accept electrons from reduced NAD is a protein complex, complex 1, called NADH (coenzyme Q
The protons go into solution in the matrix

The electron transport chain

The electrons are passed along a chain of electron carriers and then donated to molecular oxygen, the…

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The 10 molecules of reduced NAD can produced theoretically 26 molecules of ATP (Oxidative Phosphorylation)
Therefore for each molecule of reduced NAD that is reoxidised, up to 2.6 molecules of ATP should be made
Together with the ATP made form Glycolysis and Krebs cycle, the total yield of ATP molecules,…

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Structure and function of Mitochondria

Most are between 0.5m1.0m in diameter and 25m long.
Metabolically active cells (more demand for ATP) have more mitochondria.
Mammalian liver cells may each contain up to 2500 mitochondria, 20% of the cell's volume!
The Matrix:
Where the link reaction and Krebs cycle take place…

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Protons flow down a concentration gradient, through the ATP synthase enzymes, from the intermembrane space, into the matrix. This is
called Chemiosmosis
Coenzyme FAD is tightly bound to a dehydrogenase enzyme, embedded in the inner membrane. The protons accepted by the FAD do not
get pumped into the intermembrane space…

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Yeast is a facultative anaerobe it can live without oxygen. Although it is killed when the concentration of ethanol builds up to 50%
Each Pyruvate molecule loses a carbon dioxide molecule, it is decarboxylated and becomes ethanal
This reaction is catalysed by the enzyme pyruvate decarboxylase which has a coenzyme…


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