AS Biology - Biochemistry

AS Biology - Biochemistry
Covering:
Ions
Water
Carbohydrates
Lipids
Proteins
Food tests

Transcript

2. Inorganic Ion Symbol Biological uses Phosphate PO4 (3-) • Phospholipids in membranes • Component of nucleotides and ATP’s Iron Fe (2+) • Constituent of haemoglobin Calcium Ca (2+) • Strengthens and hardens teeth, shells and bones in animals • Component of middle lamella of plants and strengthens cell walls Magnesium Mg (2+) • Constituent of chlorophyll therefore important for photosynthesis
4. • Water is a dipole meaning it is neither positively or negatively charged. • Its hydrogen atoms are slightly positive (delta) • Its oxygen atoms are slightly negative (delta) • Separate water molecules are joined by weak hydrogen bonds
5. Property Biological example High latent heat of vaporisation Condensation and evaporation cools the skin when sweating Solid state floats on liquid state (Density) Organisms (Polar bears) exploit floating ice as a habitat Surface tension Organisms (Water skater) exploit the water tension as a habitat Solvent Ionic or polar substances dissolve in water Transparent Underwater plants are able to photosynthesize as sunlight penetrates the waters surface High specific heat capacity Keeps underwater environments stable Transport Blood is water based and carries substances around the body Cohesion Water molecules move up the xylem in plants in columns
7. • Made up of carbon, hydrogen and oxygen • Main energy store in plants and animals • Carbon can have 4 bonds • They readily form bonds with other carbon atoms • This allows carbon chain (of various lengths) to be formed
8. • The most basic carbohydrate monomer is a sugar (saccharide) • 1 monomer is a monosaccharide • 2 monomers are a disaccharide • 3 or more monomers are a polysaccharide
9. Monosaccharides • Sweet tasting • General formula (CH2O)n • ^ n is the number of carbon atoms
10. Monosaccharides - Glucose • Hexose sugar (C6H12O6) • Atoms form a ring structure • In Alpha glucose, there is an OH below the plane • In Beta glucose, there is an OH above the plane
11. Disaccharides • 2 monosaccharides are joined by a glycosidic bond when water is removed by condensation • This bond can be broken by the addition of water via hydrolysis
12. Polysaccharides • Chains of many monosaccharides (joined by glycosidic bonds via condensation)
13. Polysaccharide Monomer Bonds Properties Biological uses Other Starch α-glucose Amylose and amylopectin (1-4) and (1-6) Glycosidic bonds Compact Insoluble Easily hydrolysed Energy store in plants 2 polymers Branched Glycogen α-glucose Amylose and amylopectin (1-4) and (1-6) Glycosidic bonds Compact Insoluble Easily hydrolysed Energy store in animals Maintain blood sugar levels More highly branched Chitin β-glucose with amino acids Amylose and 1-4 glycosidic Strong Waterproof Lightweight Exoskeleton in insects Fungi cell walls Contains an amino acid group Unbranched Cellulose β-glucose Amylose 1-4 Glycosidic and hydrogen bonds Insoluble Rigid Plant cell walls Microfibrils are formed between 60- 70 chains Unbranched
15. • Contain carbon, hydrogen and oxygen but more carbon and less oxygen than carbohydrates • Non polar molecules • Insoluble in water but will dissolve in organic solvents like alcohol
16. Triglycerides • Made up of 1 glycerol backbone and 3 fatty acids • Joined by an ester bond formed by condensation • Glycerol is hydrophilic and the fatty acids are hydrophobic
17. Fatty acids Unsaturated • C=C double bonds • Contain less hydrogen atoms • Double bonds create a ‘kink’ in the chain • Most likely to be liquid at room temperature • Example: Sunflower oil Saturated • No C=C double bonds • Contains more hydrogen atoms • Straight chain • Most likely to be a solid at room temperature • Example: Animal fat/lard
18. Human health HDL’s (High Density Lipoproteins) • Diet high in unsaturated fat • Carry harmful fats away from arteries for disposal • The higher HDL:LDL ratio the lower the persons risk of heart/cardiovascular disease LDL’s (Low Density Lipoproteins) • Diet high in saturated fat • Causes the deposit of atheroma (fatty deposits) in the arteries • Causes atherosclerosis • Blocks blood from travelling to and from the heart
19. Phospholipids • Phosphorus is present in the phosphate head • 2 fatty acid tails • Phosphate head is hydrophilic and the fatty acids are hydrophobic • They’re like a duck (head in the water and the tail sticks out of the water)
20. Waxes • Form of lipid • Melt at temperatures at 45°c
21. Lipid Role Biological example Triglycerides Thermal insulation Prevents heat escaping in cold climates and heat gain in warm climates “ Protects against mechanical damage Fat gathers around delicate organs such as the kidneys “ Energy store In plants as oils In animals: gram for gram, fats yield more than twice as much energy as carbohydrates “ Metabolic source of water Water released during chemical reactions in the body (respiration) Phospholipids In biological membranes Cell membranes “ Electrical insulation Myelin sheath that surrounds the axon of nerve cells Waxes Waterproofing In plants, waterproof the waxy cuticle In animals, waterproof the exoskeletons of insects
23. Amino acids • Amino acids are the monomers of proteins • Contain an ‘R’ group (which varies with each amino acid) a carboxyl group and a amine group (which contains nitrogen) • There are 20 different amino acids in human biology
24. Polypeptides • Polymerisation occurs via condensation • Forms peptide bonds • 2 peptides bonded form a dipeptide • 3 or more peptides form a polypeptide chain
25. Protein structure - Primary • Sequence of amino acids in a polypeptide chain • Linked by peptide bonds (and no others)
26. Protein structure - Secondary • Folding of the primary structure • Linked by hydrogen bonds • Folded into an α-helix (DNA) or a β-pleated sheet
27. Protein structure - Tertiary • Secondary structure is further folded into a 3-D structure (alpha helix is folded into globular proteins) • Maintained by hydrogen, ionic, disulphide, covalent and hydrophobic bonds
28. Protein structure - Quaternary • Formed by the joining of 2 or more polypeptides in their tertiary structure • Form large molecules such as haemoglobin • Held together by hydrogen bonds (sometimes disulphide)
29. Protein structure - Classification Globular (Haemoglobin) • Function as enzymes, antibodies and some hormones (insulin but not testosterone) • Secondary structures are spherical shaped • Tertiary structure is important (enzyme active sites) • Soluble in water Fibrous (Collagen) • Structural roles (Keratin for hair and animal horn growth) • Remain in secondary structure in parallel chains with cross linkages • Alpha helixes linked into strands • Insoluble in water
31. Reducing sugar (Glucose) • Benedict's reagent (blue) • Add glucose (sugar in question) and boil • If a reducing sugar is present, solution will turn brick red
32. Non-reducing sugar (Sucrose) • Boil sucrose (sugar in question) in HCL (acid) • Cool • Neutralise with NaOH (alkali) • Add equal amount of Benedict’s reagent (blue) • Boil • If a non-reducing sugar is present, the solution will turn brick red
33. Lipid • Dissolve lipid in ethanol (acid) • Pour into test tube of water • The lipid will separate from the solution and create a milky white emulsion
34. Starch • Add a few drops of iodine (brown/orange) • If starch is present, solution will turn blue/black