Biochemistry Revision - OCR AS Level

These are just some notes that I created for my Biology AS Module. They are detailed but skip out all of the unnessessary stuff that you dont need to know. :)

Hope it helps :)

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  • Created on: 09-05-11 20:08
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Biology Revision ­ Biochemistry OCR
Biochemistry and metabolism
Page 88
Learning objectives
1. State the functions of biological molecules in organisms.
2. Define metabolism.
You are what you eat
The nutrients any organisms takes in build and maintain a healthy body because they
become part of our body and they are used to provide the energy needed to drive
metabolism (living processes).
Substances taken into the body that are indigestible are removed from the body. They are
unable to take part in metabolic processes.
A risk factor is a factor that increases your chance of developing a particular disease.
The nutrients required
Organisms are made up of many thousands of different molecules in order to survive the
body must be able to take in all of the required molecules.
Note a fibre is usually included in `nutrients required' lists for humans ­ fibre is a type of
Chemical group Role / Function
Carbohydrates Energy storage and supply, structure (in
some organisms).
Proteins Structure, transport, enzymes, antibodies,
most hormones.
Lipids Membranes, energy supply, thermal
insulation, protective layers/padding,
electrical insulation in neurones, some
Vitamins and minerals Form part of some larger molecules and
take part in some metabolic reactions, some
act as coenzymes or enzyme activators.
Nucleic acids Information molecules, carry instructions for

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Biology Revision ­ Biochemistry OCR
Metabolism refers to the sum total of all the chemical reactions that take place in an
organism. These reactions include the breaking of larger molecules. These metabolic
reactions are known as catabolic reactions and example is digestion.
Anabolic reactions are when smaller molecules are built into larger molecules.
Carbon is very special
Organic chemistry is the study of chemical reactions that involve carbon. Carbon atoms are
able to bond together to form long chains and rings.…read more

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Biology Revision ­ Biochemistry OCR
In some cases carbon forms two bonds with another atom, C = C (hydrocarbon chain)
C = O is a double bond found in many molecules, including organic acids.
Monomers and polymers
The term monomer refers to a single, small molecule, many of which can be joined together
to form a polymer. This only occurs in carbohydrates, proteins and nucleic acids.…read more

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Biology Revision ­ Biochemistry OCR
Hydrogen bonds
Polymers often have specific functions that rely on their shape. Hydrogen bonds form when
a slightly negative charged part of a molecule comes close to a slightly positive charged
hydrogen atom in the same (or another) molecule.
Hydrogen bonds are not strong bonds (often described as interactions).
However in large molecules the formation of hydrogen bonds can contribute to the stability of
a molecule.
Carbohydrates 1: simple sugars
Page 92
Learning objectives
1.…read more

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Biology Revision ­ Biochemistry OCR
Carbohydrates contain the elements carbon, hydrogen and oxygen, they are found in the
form Cn(H2O)n. This means that for every carbon present in a carbohydrate, the equivalent
of a water molecule is also present.
Simple sugars
The simplest carbohydrates area called monosaccharides. These are the basic units
(monomers of carbohydrates) larger carbohydrates are made by joining monosaccharides
There is number of different monosaccharides containing between three and six carbon
atoms (they have very similar properties).
1.…read more

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Biology Revision ­ Biochemistry OCR
Animal and plant enzymes are unable to break down beta glucose due to the shape of the
molecule and the position of the hydroxide ion on carbon1 , this therefore means that the
enzymes shape fit the alpha glucose making it able to be respired.
Carbohydrate polymers ­ stores of potential energy
Two alphaglucose molecules bonded together form a disaccharide called maltose.…read more

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Biology Revision ­ Biochemistry OCR
The glycogen can form glycogen granules in animal cells (especially liver and muscle cells).
Features of the energystorage molecules starch and glycogen
The starch and glycogen are termed as energystorage molecules because they are made
by bonding many thousands of alpha glucose molecules together.
They do not dissolve, so the stored glucose does not affect the water potential of the cell.…read more

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Biology Revision ­ Biochemistry OCR
Figure 1
These straight line chains can contain 10'000 beta glucose molecules. They are stronger
than the chains found in amylase. The beta glucose polymer chains are called cellulose
Cellulose fibres are arranged in a very specific way to form plant cell walls. Because glucose
monomers contain so many OH groups, many hydrogen bonds can form.
About 6070 cellulose molecules become cross linked to form bundles called micro fibrils.…read more


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