F212: Molecules, Biodiversity, Food and Health

My revision notes I made, I hope you might find them useful :)

(All ideas and definitions from Heinemann OCR Biology text book)

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  • Created on: 01-01-13 15:10
Preview of F212: Molecules, Biodiversity, Food and Health

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Metabolism is the sum total of all the biochemical reactions taking place in the cells of an organism.
Anabolism is the building of small molecules to produce larger ones ­ requires energy.
Catabolism is the breakdown of large molecule into smaller ones ­ releases energy.
Carbohydrates Energy storage and supply, structure
Proteins Structure, transport, enzymes, antibodies, most hormones
Lipids Membranes, energy supply, thermal insulations, electrical insulation in neurones, some
hormones, protective layers/padding
Vitamins and Form parts of larger molecules and take part in some metabolic reactions,
Minerals coenzymes or enzyme activators.
Nucleic Acids Information molecules, carry instructions for life
Water Reactions, support in plants, solvent/medium for metabolic reactions,
Hydrolysis reactions use a water molecule to break covalent bonds and breakdown larger molecules
into smaller ones and are catalysed by enzymes.
Condensation reactions release a water molecule when a new covalent bond is formed between
smaller molecules to make a large one and are catalysed by enzymes.
Monomer Polymer
Carbohydrate Monosaccharides Polysaccharides
Protein Amino Acid Polypeptides and proteins
Nucleic Acids Nucleotides DNA and RNA
Carbon atoms Sugar Example
3 Triose Triose phosphate
5 Pentose Ribose/Deoxyribose
6 Hexose Glucose/Fructose
Soluble in water
Sweet tasting
Form crystals
Contains carbon, hydrogen and oxygen
Alpha-Glucose Beta-Glucose

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Alpha glucose has an OH molecule below the plane on C1 and above the plane in beta-glucose.
Glucose + Galactose = Lactose
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Oxygen CO2 + energy (ATP)
-glucose can be respired and -glucose
cannot as different enzymes breakdown
-glucose and -glucose because they
have different arrangements of H and OH
at C1.
Starch is found in plants and is a mixture of amylose and amylopectin.…read more

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Functions of cell walls:
Strength and support
Arrangement of macrofibrils allows water to move in and out of the cell
Cells become turgid preventing the cells from bursting.
Macrofibril arrangement determines cell growth and shape.
Cell walls can be reinforced with other substances e.g. lignin waterproofs cells.
Amino Acids
There are 20 different types of amino acids, and the differences are caused from varying R groups.…read more

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Tertiary Structure is the 3D shape of a protein, formed by the further folding and coiling of the
pleated sheets and helix's held together by R group interactions. These interactions may be hydrophilic
and hydrophobic, ionic bonds, di-sulphide bonds or hydrogen bonds. An increase in heat causes the
protein to vibrate and breaks some of the bonds holding the structure together, denaturing the
protein.…read more

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A covalent bond, called an ester bond forms between three fatty acids and a glycerol by a condensation
reaction, producing a water molecule. Triglycerides are insoluble in water because the charges on the
molecule are evenly distributed (non-polar), so hydrogen bonds cannot form around the molecule.
A phospholipid consists of a glycerol and two fatty acids,
bonded in ester bonds and a phosphate.…read more

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Property Importance Examples
Solvent Any molecule that is polar will dissolve in water. The 70-95% of cytoplasm is water.
solutes dipoles will interact with water molecules Dissolved chemicals take part in
which cluster around the molecules keeping them processes such as respiration and
apart. Once in a solution the molecules can move photosynthesis in living organisms.
around and react with other substances.
Metabolic processes in all organisms rely on
chemicals being able to react together in a solution.…read more

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Lipid 1. Add ethanol to extract (dissolve) lipid White emulsion No
2. Pour solution into water in another test tube on surface emulsion
1. Test known concentration of reducing sugars, using the Benedict's test.
2. The more reducing sugar present, the more precipitate will be formed and more Benedict's
solution will be `used up'.
3. Filter the precipitate ­ the higher the concentration the lighter the filtrate.
4. Use water to calibrate the colorimeter.
5. Use a red filter.
6.…read more

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Two polynucleotide chains come together by the hydrogen bonding between base pairs. The strands
are anti-parallel (strand run in opposite directions), which provides strength. The antiparallel chains
twist forming a double helix.
Complimentary base paring rules:
Pyrimidine: (single ring) cytosine, thymine, uracil.
Purine: (double ring) adenine, guanine.
A-T/U are bonded by 2 hydrogen bonds.
C-G are bonded by 3 hydrogen bonds.
DNA Replication
1. DNA double helix unwinds
2. Hydrogen bonds between bases are broken and
the DNA `unzips'.
3.…read more

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Intracellular enzymes catalyse reactions inside the cell.
Extracellular enzymes catalyse reactions outside the cell.
Nutrition and digestion
Saprophytes secrete extracellular enzymes e.g. bacteria and fungi
Enzymes are involved in digestion ­ breaking of glycosidic, peptide and ester bonds are catalysed
by different enzymes.
Heterotrophs need to break down the body of organism they are digesting.
Many enzymes are found in the cytoplasm of cells.
Some enzymes break down pathogens e.g. lysins.…read more

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H+ are attracted to negatively charged species' and repelled by positively charged species'. Hydrogen
and ionic bonds are responsible for holding the tertiary structure of an enzyme together, and
maintaining the shape of the active site. H+ can interfere with these bonds, and so altering the
concentration of H+ ions alters the tertiary structure, charge and the shape of the active site.…read more


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