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Unit 1 Biology and disease













AQA




AS Biology



Unit 1:



`Biology & Disease'



Summary Notes






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Unit 1 Biology and disease



Biochemistry

Organisation of matter
Matter: anything that occupies space and has mass.
All forms of matter are made up of elements.
The elements hydrogen, carbon and oxygen make up most of the human body.
Atoms: the smallest unit of matter that are unique to a…

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Unit 1 Biology and disease





Examples:
o Between water molecules.
o Between water and ammonia.
o Between water and glucose.
o Within DNA ­ base pairing.

Polymers and Monomers

Biological molecules such as carbohydrates and proteins are often polymers and are based on a
small number of chemical elements.

Group…

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Unit 1 Biology and disease



General formula CH2On
Glucose C6H12O6.
Hexose sugar.
Main substrate for respiration.
Transported in mammalian blood.
Monomer for starch, glycogen and cellulose.
The structure of glucose:





glucose link together by glycosidic bonds
This is a condensation reaction Involves the loss of a water molecule.
It joins…

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Unit 1 Biology and disease




Polysaccharides
Polysaccharide = `many sugars'.
Polymers of monosaccharides.
Formed by condensation reactions.
Variable numbers of monosaccharides.
Branched or unbranched chains.
May be folded.
Insoluble due to size.
Exert no osmotic influence.
Do not diffuse easily.
Split into disaccharides and monosaccharides by hydrolysis.

Starch
Found in…

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Unit 1 Biology and disease



Proteins

Polymers of amino acids.
Large molecular mass.
Wide variety of functions.
Carbon, hydrogen, oxygen and nitrogen.
Usually sulphur as well.
Each species has a particular range of proteins.
Determined by the genetic code.
Make up twothirds of total dry mass of cell
Make up…

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To break this bond requires a hydrolysis reaction.
This requires the use of a water molecule to reform the amino and caboxyl groups on each of the
two new amino acids where the bond is split.

Polypeptides
Many amino acids make up a polypeptide chain.…

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Unit 1 Biology and disease



A zigzag formation
Consisting of two or more chains
Running parallel to each other
Linked by hydrogen bonds.







Tertiary structure
Overall threedimensional shape formed by the folding up of a whole polypeptide chain.
Every protein has a unique tertiary structure, which is responsible for its…

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Unit 1 Biology and disease



Globular Proteins:
More spherical.
Smaller ones are soluble.
Specific shape.
Tertiary and quaternary structure forms specific shape.
Often part of the protein has a complementary shape to another specific molecule.
Examples:
o Hormones ­ eg insulin and glucagon attach to receptors on cell membranes
o…

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