Proteins and mutations

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Grouping organisms

All proteins are made of long chains of amino acids joined together.

Proteins have different functions, some examples are:

  • structural proteins are used to build tissues, eg; collagen.
  • hormones which carry messages to control a reaction, eg; insulin controls blood sugar levels.
  • carrier proteins, eg; haemoglobin which carries oxygen.
  • enzymes.

Each protein has its own number and order of amino acids. This makes each type of protein molecule a different shape and gives it a different function. 

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Enzymes speed up reactions in the body and this is why theyre called biological catalysts.

They catalys chemical reactions occuring in respiration, photosynthesis and protein synthesis of living cells.

The substrate molecule fits into the active sit of the enzyme, this explains why each enzyme can onky work on a particular substrate.

Enzymes work best at a particular temperature (body temp [37*c ish]) and pH. This is called the optimum.

  • At low tempertatures molecules are moving slowly and so the enzyme and substrate are less likely to collide.
  • At very high/low pH or high temperatures the enzymes active site changes shape, this is refered to as denaturing.

It is possible to work out how temperature alters the rate of reaction by calculating the temperature coefficient, called Q10. This is done for a 10*c change in temperature and by using

Q10 = rate at higher temperature/rate at lower temperature

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Mutations may occur spontaneously but can be made to occur more often by radiation or chemicals.

When they occur, mutations:

  • may lead to the production of different proteins
  • are often harmful but may have no affect
  • occasionally they might give the individual an advantage

Although every ceek in the body has the same genes it does not mean that all the same proteins are made, this is due to the fact different genes are switches off in different cells, and this allows the different cells to preform different functions.

Gene mutatuons alter or prevent the production or the protein that is normally made, because the change the base code of DNA (a mutation changes the order of the four bases) and so they change the order of amino acids in the protein.

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