BY1 Biochemistry (1.1) Revision Notes

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  • Created on: 03-01-13 14:42
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Biochemistry 1.1
Main properties of water
Ice is less dense than water in its liquid form (forming an insulating layer allowing organisms
to survive underneath)
High Surface Tension (Jesus Lizard)
Strong cohesive properties (water attracted to water, held together by hydrogen bonds)
Colourless (Photosynthesis)
High specific heat capacity (Stable conditions for aquatic organisms)
High latent heat of vaporisation (Sweating)
Importance to living organisms
Examples: Hydrostatic skeleton (support), Removal of wastes (solvent),
Mucus (lubricant), Diffusion
Water is a polar molecule, although it is electronically neutral the
distribution of charges are unequal.
Carbohydrates are compounds of C, H and O
Source of energy in plants and animals.
Provides strength and support for cell membranes, cell walls and insect skeletons.
Three types:
Monosaccharide formula Cn H2n On (n= number of carbon atoms)
Triose- 3 carbon atoms.
Pentose-5 carbon atoms
Hexose- 6 carbon atoms

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Glucose, Fructose and Galactose are examples of Hexoses.
Glucose exists in two forms: alpha glucose and beta glucose
They have the same
structural formulas, but
different structures. We call
them structural isomers.
On carbon atom 1 OH and H
have interchanged.
When two monosaccharides join together they form a disaccharide. The reaction releases water so it
is called a condensation reaction. The link between monosaccharide rings is called a glycosidic bond.…read more

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Reducing Sugars have carbonoxyl groups (C=O) which can be oxidised to carboxylic groups (-COOH)
They therefore react with Benedict's reagent to produce a precipitate
The colour of the solution depends on
the amount of the reducing sugar.
For example, a high amount of the
reducing sugar reacting with the
benedict's agent would give a red
precipitate.…read more

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Test for Starch- Add Iodine to solution, turns black if there is a positive result.
Cellulose is a structural polysaccharide made up of multiple
units of Beta glucose held together by 1,4 glycosidic bonds
forming long unbranched chains. These long, parallel chains of
Beta glucose are cross-linked to each other by hydrogen
bonds forming micro fibrils.
Cellulose gives plant walls their strength and rigidity.
Humans are unable to digest cellulose, but herbivores can as
they have bacteiria in their guts that make enzymes called cellulases.…read more

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Triglycerides (the most common type of lipid)
They are formed as a result of three
condensation reactions involving the ­OH
of glycerol and ­COOH of each fatty acid
(forming an ester bond.…read more

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Made up of C,H,O,N and some also contain Sulfur and Phosphorus
Made up of sub units (amino acids)
There are 20 different kinds of amino acids
(but thousands of different types of protein.)
The `R' group varies depending on the kind
of amino acids
In a solution the amino group can act as
acid by giving up H+ forming a positively charged
amino acid ion.…read more

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Protein Structures
(B)3D structure
Held together by hydrogen
(C) Complex 3D shape, when
the polypeptide helix twists
and fold around itself.
Hydrogen and Disulphide
bonds present
(D)Linking together of a
number of polypeptide
chains. Hydrogen and
Disulphide bonds present. Example- Haemoglobin.…read more

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An increase in temp. will cause atoms in the protein molecule to vibrate, breaking the protein bonds.…read more



Do you have any revision material for the rest of the BY1 unit? :) ***

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