1. Proteins

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Proteins
Proteins are natural products formed by many plants and all animals.
All proteins contain carbon, hydrogen oxygen & nitrogen.
Nitrogen comes from either the air, fertilisers or from the action of bacteria in nodules on some plant routes.
Proteins are condensation polymers made by linking together many amino acids.

3. Amino acids.. N H C O OH
As the name suggests; contain both an acid group
And an amino group (NH2) R

4. Condensation polymerisation
Peptide link
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5. Proteins
Different proteins are used for different processes in the body.
The body cannot produce all the amino acids required for body proteins.
Therefore essential amino acids must come from dietary proteins.

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Digestion
During digestion protein molecules are broken down or hydrolised to produce a mixture of amino acids. This process is catalysed by enzymes.
The amino acid can then pass through the gut wall into the bloodstream.

7. Hydrolysis of proteins
The structural formula of the amino acid released from the protein can be identified by looking at the corresponding section of the protein chain.
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8. Protein classification: Fibrous
Fibrous proteins are long and thin. They are the major structural materials for animal tissue; keratin, (hair, nails & feathers) collagen (muscles), fibroin (in silk).
Generally insoluble in water & resistant to acids & alkalis.
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9. Protein classification: Globular
Globular proteins have spiral chains folded into compact units.
Globular proteins are involved in maintenance and regulation processes due to their solubility.
Examples include all enzymes, many hormones, haemoglobin and antibodies.
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10. Enzymes
Enzyme function is related to the molecular shapes of proteins.
Denaturing of a protein involves physical alteration of the molecules as a result of temperature change or pH change.
The ease with which a protein is denatured is related to the susceptibility of enzymes to changes in temperature and pH.
Enzymes are most efficient within a narrow range of temperature and pH.
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Enzymes
Enzymes are all globular proteins. Enzymes catalyse specific reactions because of their specific active site.
Only molecules with the correct shape will fit onto the surface and it is only these molecules which will react using that particular enzyme as a catalyst.

12. When the enzyme is heated or the pH altered the shape of the molecule may change because the pattern of intermolecular bonding between chanes in altered.
Chemists and biologists call this change to the enzyme denaturing since it can no longer carry out the specific reaction it was originally used for. W

13. Some enzymes are more easily denatured that others which means that a slight change in temperature or pH can cause a large change in the enzymes ability to catalyse a reaction.
Other more robust enzymes require a much greater shift in conditions to alter their activity. W

14. Enzyme X functions over a narrower range of temperature than enzyme Y
Enzyme X functions over a narrower range of temperature than enzyme Y. Both enzymes have an optimum temperature/pH.
Enzyme X
Enzyme Y W