Biological Molecules

OCR AS-level BiologyTopic 3 of 1263 lessons

Revision notes for Biological Molecules in OCR Biology A (H020). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.

1. ElementsThere are about 114 naturally occurring elements.
2. BondingThe atoms in organic compounds are held together by strong covalent bonds.
3. IonsAtoms are electrically neutal because the number of protons is equal to the number of electrons and the electron and proton have equal and opposite…
4. Biological MoleculesThe key biological molecules are carbohydrates, lipids, proteins and nucleic acids.
5. PolymersSome biological molecules are very large (macromolecules).
6. WaterWater is a polar molecule.
7. Hydrogen Bonding and Boiling Point of WaterThe boiling point of water is unusually high for a small molecule of its size.
8. Density of WaterWhen water freezes, bonds form between the water molecules and it turns into ice.
9. Cohesion, Adhesion and Surface TensionWater molecules are cohesive.
10. Specific Heat Capacity of WaterThe specific heat capacity is defined as the energy required to raise the temperature of 1kg of a substance by 1°C.
11. Water as a SolventWater is a polar solvent because water molecules have partial charges.
12. CarbohydratesCarbohydrates are organic molecules that only contain carbon, hydrogen and oxygen with the general formula Cn(H2O)n.
13. GlucoseGlucose is a hexose sugar.
14. Other MonosaccharidesMonosaccharides are simple carbohydrates called sugars.
15. Condensation ReactionsA condensation reaction is a reaction that joins two molecules together with a covalent bond formed by removing a small molecule such as a water…
16. HydrolysisHydrolysis is the process by which a covalent bond is broken by the addition of a water molecule.
17. DisaccharidesTwo monosaccharides joined together by a covalent bonds is called a disaccharide.
18. Test for Reducing SugarsMonosaccharides such as glucose, fructose and galactose can donate electrons to other compounds.
19. Test for Non-Reducing SugarsNon-reducing sugars must first be hydrolysed before using the Benedict's test.
20. StarchStarch is an energy storage polysaccharide found in plants.
21. Test for StarchA few drops of iodine in potassium iodide solution are added to the sample.
22. ColorimetryColorimetry can be used as a quantitative method to determine concentrations.
23. GlycogenGlycogen is a storage polysaccharide found in animals, fungi and bacteria.
24. CelluloseCellulose is a polysaccharide made from beta-glucose.
25. BiosensorsBiosensors are biological molecules that can be used to detect the presence of another biological molecule such as glucose or can be used to…
26. LipidsLipids are part of a group of large molecules called macromolecules.
27. TriglyceridesTriglycerides consist of three fatty acids joined to a glycerol molecule by three ester bonds in a condensation reaction.
28. Saturated and Unsaturated Fatty AcidsSome fatty acids contain C=C double bonds and are said to be unsaturated.
29. PhospholipidsPhospholipids contain the elements carbon hydrogen, oxygen and phosphorus.
30. SterolsSterols are steroid alcohols and include cholesterol and vitamin D sterols.
31. Roles of LipidsTriglycerides are stored under the skin in mammals and around vital organs.
32. Test for LipidsThe test for lipids is called the ethanol emulsion test.
33. Lipids and HealthPlant lipids are normally oils because they contain unsaturated fatty acids.
34. Amino-acidsAmino acids are monomers that combine to make polymers called polypeptides.
35. Thin Layer ChromatographyThin layer chromatography is used to separate components of a mixture.
36. PolypeptidesThe amine group of one amino acid can react with the carboxylic acid group of another amino acid in a condensation reaction to join the two amino…
37. Protein StructureThe primary structure of a protein or polypeptide is the sequence of amino acids joined together by peptide bonds.
38. Hydrolysis of PeptidesPeptides can by hydrolysed by the addition of a water molecule to form individual amino acids.
39. Globular ProteinsGlobular proteins are water soluble proteins that fold and coil into a tertiary structure in a way that positions hydrophobic R-groups inside the…
40. InsulinInsulin is a peptide hormone produced by the pancreas.
41. Conjugated ProteinsConjugated proteins contain a non-protein prosthetic group.
42. HaemoglobinHaemoglobin is a globular protein containing iron that facilitates the transport of oxygen in red blood cells.
43. CatalaseCatalase is an enzyme that catalyses the breakdown of hydrogen peroxide to oxygen and water.
44. Fibrous ProteinsProteins perform many different functions in the cell.
45. KeratinKeratin is fibrous protein in hair, scales, nails, feathers, horns, claws, hooves, and the outer layer of skin among vertebrates.
46. ElastinElastic fibres contains the fibrous protein elastin.
47. CollagenCollagen is a fibrous protein that is found in tendons, bones, muscles, skin and blood.
48. Test for ProteinsThe Biuret test detects the presence of peptide bonds.
49. NucleotidesA nucleotide is an organic compound made of three parts: a pentose sugar - a five carbon sugar such as ribose or deoxyribose An acidic phosphate…
50. DNADNA is deoxyribonucleic acid.
51. RNARNA is a polynucleotide.
52. DNA Extraction1.
53. Role of RNASome RNA is involved in regulating transcription and mRNA breakdown. mRNA, rRNA and tRNA are involved in protein synthesis. mRNA transfers genetic…
54. DNA ReplicationOrganisms grow and reproduce by cell division.
55. Continuous and Dis-continuous ReplicationDNA can only be synthesised in the 5' to 3' direction.
56. Replication ErrorsSequences of bases are not always matched exactly.
57. The Genetic CodeThe genetic code is the information contained in DNA that allows functional proteins to be synthesised.
58. Protein SynthesisThe sequence of nucleotides determines the sequence of amino acids in proteins.
59. The role of tRNA, mRNA and rRNAThere are three types of RNA: mRNA, tRNA and ribosomal RNA or rRNA.
60. TranscriptionProtein synthesis consists of two stages.
61. SplicingSplicing pre-mRNA In eukaryotes, transcription results in pre-mRNA with is a length of RNA with both non-coding and coding sequences.
62. TranslationOnce the mRNA leave the nucleus a ribosome attaches to the start codon (triplet of bases) which is always AUG.
63. ATPATP is the immediate energy source of a cell.

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