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BIOCHEMISTRY NOTES FOR STANDARD LEVEL Recommended units and SI units
Distance (m); mass (kg); time (s, min, h, day, month or a);
temperature (°C, rarely K in biology);
volume (cm3 or dm3 );
amount of substance (mol); force (N); pressure (Pa or atmospheres or mm Hg); potential difference (v); energy (J or cal); power (work) (W); illumination (lx)
Chemical terms to know
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atom the smallest part of an element
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molecule the smallest particle of a substance which can exist in a free state (e.g. O2).
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compound a molecule or particle made of different elements (e.g. H2O)
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element a type of atom, a substance which cannot be further divided by chemical methods e.g. oxygen
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electromagnetic spectrum waves of energy (e.g. light rays, UV & infra red radiation)
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electron (e-), proton (H+), ion (a charged particle), cation (a positively charged particle e.g. Na+ or Ca2+), anion (a negatively charged particle e.g.
Cl- or NO3-),
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solution = solute (substance: solid, liquid or gas) + solvent (liquid).
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hydrophobic repelled by water, hydrophilic attracted to water.
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suspension very small solid particles dispersed in a liquid.
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sediment solid particles which settle to the bottom of a liquid.
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precipitate a solid produced from a reaction in a solution.
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diffusion the movement of molecules from an area of high concentration to an area of low concentration.
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dialysis selective diffusion of particles through a partially permeable membrane.
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osmosis the movement of water across a partially permeable membrane from a region of high solute concentration to a region of low solute concentration.
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covalent bond a strong bond formed by the sharing of electrons between two atoms e.g. the peptide bond between amino acids.
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hydrogen bonding a weak bond between hydrogen and a negative element e.g. between hydrogens and oxygens of different water molecules,
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hydrolysis the breaking of a covalent bond between two organic molecules using water (NB not dissolving in water)
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condensation the formation of a strong covalent bond between two organic molecules releasing water.
Elements of biological importance
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H, O, C, are the most common.
N, S, P are also important as well as the metals Na, Ca, and Fe.
H, O, C, N, S and P form covalent bonds (single, double or triple
e.g. C-C-, -C=O, C N).
H, O, C, N, S and P are light.
H, O, C, N, S and P very reactive.
H, O, C, N, S and P produce diverse compounds which are reduced (readily oxidised).
CARBON
Tetravalent
4 different bonds
variety
isomerism.
Forms long chains (polymers)
macromolecules and ring structures.
Tetrahedral structure
3 D variation
optical isomerism.
Organic compounds
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Compounds containing carbon found in living organisms.
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Not including carbonates, hydrogen carbonates, CO2 or CO.
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Often based upon a skeleton of carbon.
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An infinite variety possible.
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Evolution has chosen a few for use in living organisms.
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There are four principal groups: sugars, fatty acids, amino acids and nucleotides
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© Paul Billiet 2008 |