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The Structure and functions of proteins Essay

Proteins are made up of long chains of amino acids, just a chain of ami. tacids makes up the primary structure. The secondary structure is formed by hydrogen bonds joining the chains in certain places to make an alpha helix or a beta sheet. The tertiary structure is formed by even more folding and joining of the chains to make a globular mass or fibrous mass. An example of this would be a carrier protein.

Proteins are needed for many things they are needed in our diet for growth and repair of cells, enzymes and hormones in the body are used for the mateabolic rate. Essential amino acids are the amino acids that we have to get in our diet to make proteins. Non essential are the ones we already have and do not need to gain from our diet.

Proteins are also in the skin of human beings in the form of collagen, this makes up 30% of the body protein, glucose attach to the amino aciss in collagen molecules, the cross linkage makes fibres that are stretchy and easy to repair.

Proteins are used indigestion. Endopeptidases break down large molecules into smaller molecules by breaking chains in the middle. Exopeptidases break chains at the ends to make amino acids and dipeptides.Proteins are also featured in th phospholipid bilayers where they play a big part in diffusion etc. They are used as carrier to water soluble molecules, pumps wherby ATP is used to move water soluble molecules. Receptors are also proteins-these enable hormone and nerve transmittors to bind to specific cells, to the recognition sites as in enzymes. Glycoproteins act as receptors and recognition sites. Carrier proteins bind to a specific molecule, this inturn changes shape to get through the membrane surface to the other side of the membrane.

Ion channels are also made of proteinwith a central pore that is lined by charged groups, diffusion of charged ions take place here. Some pores are gated and can open or close. The gates are in place so that the cells can regualte the flw of ions from one cell to another, no ATP is needed.

Heat can cause a protein to denature, this takes place when the hydrogen bonds break.

Ribonuclease is an examle of an enzyme, it breaks down nucleic acid RNA, it has an active site, it is a tertiary structure and is therefore globular.

Antibodies are proteins and make our immune system systemas effective as is it. The antibodies join to the active sites of harmful micro-organisms, the infection is thus controlled and destructed. Each antibody has a specific binding site for a specific antigen.

The nervous system has protein receptor molecules..These are in the neurones. An impulse hits the nerve and travels to the synapse.Molecules odf the neurotransmitter substance are released and diffuse across gaps to fit into the protein receptor molecules, this results in nerve impulse in the second neurone.

Enzymes are also proteins and play a massive part in speeding up reactions.

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