Biological Molecules

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  • Created by: MEK
  • Created on: 16-03-13 08:39


A molecule is one or more different types of non-metal atoms covalently bonded together.

In biology there are 3 different types of molecules that we can talk about:-
- Carbohydrates
- Proteins
- Lipids (Fats) 

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Carbohydrates are the first type of biological molecule. These are made of carbon, hydrogen and oxygen. 

You can divide cabohydrates up into there monomers and polymers.
The monomer is the most basic substance contained in the molecule. In carbohydrate this is sugar.

Sugar makes up all the different types of carbohydrate. 

These can be simple sugars like glucose, fructose or sucrose; or they can be a complex carbohydrate like starch, cellulose or glycogen.

Simple sugars contain only one of each monomer or unit.
However, complex carbohydrates contain many simple sugar units. Like starch which contains many units of glucose in a long chain. 

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In proteins, we can find the chemical elements carbon, hydrogen, oxygen, nitrogen and sometimes sulphur; (C, H, N, O, (S)).

The monomer in protein is amino acids. There are over 20 diferent types of amino acids that all bond in long chains to make proteins.

If a chain of amino acids is in a long line, then it is considered unfolded but if it is in a specific shape, it is folded.

Proteins are used as structural components of tissue like muscle. They can also act as haemoglobin, hormones, antibodies and enzymes.

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Lipids (Fats)

The final biological molecules are lipids or fats. 

Like in carbohydrate, in lipids we can find the chemical elements hydrogen, carbon and oxygen. However it is the way in which lipids are bonded that makes them different.

In a lipid, the monomers are glycerol and fatty acids.

You get a molecule of glycerol bonded to three fatty acid molecules.

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Enzymes: An introduction!

Enzymes are a type of biological molecule, specifically a protein. 
"Enzymes are proteins that control reactions in living organisms. They are called biological catalysts because they speed up the rate of reaction without being used up. Enzymes are unchanges by each reaction."

This is how an enzyme works whether it's a builder (creates a product) or a breaker (creates broken down product. 

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How can enzymes be affected? (part 1)

Enzymes can be affected by two things; pH and temperature. 

Temperature: From A to B as the temperature increases the rate of reaction increases also. This happens up to the optimum temperature of 40 degrees celsius. From B to C, as the temperature continues to increase, the rate of reaction and enzyme activity decreases.

This is because from A to B, the temperature increases and the enzymes and substrates gain kinetic energy and vibrate more vigorously. Therefore, the enzymes and substrates are more likely to collide and react. The rate of reaction is increased. Beyond the optimum temperature of 40 degrees celsius (from B to C), the enzymes gain so much kinetic energy and vibrate so fast that the shape of their active site changes. Therefore, substrates can no longer fit and the enzyme cannot work. The enzyme is denatured.

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How can enzymes be affected? (part 2)

pH: From A to B, as the pH increases, as does the enzyme activity. This happens up to pH8. After this point, as the pH continues to increase, the enzyme activity decreases. The enzyme activity stops completely at pH10.5

This is because enzymes work best at an optimum pH of 8. Any pH other than the optimum and the active site of the enzyme changes. The further away you get from the optimum pH, the more the active site of the enzyme changes shape. This continues until the enzyme is so denatured that reactions cannot take place at all. 

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