Biological molecules — AQA A-Level Biology
In summary: Biological molecules is a key topic in AQA A-Level Biology. Key exam tip: Always mention the specific bond type when describing the formation of polymers.
Exam Tips for Biological molecules
- Always mention the specific bond type when describing the formation of polymers.
- When describing enzyme-substrate complexes, refer to the tertiary structure of the active site.
- Use the term 'complementary' when discussing base pairing or enzyme-substrate binding.
- Ensure you can distinguish between the roles of DNA helicase and DNA polymerase.
- Practice drawing the general structure of an amino acid and identifying the R-group.
Common Mistakes
- Confusing condensation and hydrolysis reactions.
- Failing to specify the role of water in condensation/hydrolysis.
- Incorrectly identifying the bonds (e.g., peptide vs phosphodiester).
- Confusing the structure of alpha-glucose and beta-glucose.
- Misunderstanding the role of hydrogen bonds in protein tertiary structure versus DNA double helix.
- Inaccurate description of the semi-conservative replication process.
Marking Points
- Condensation reactions join molecules by forming a chemical bond and eliminating water.
- Hydrolysis reactions break chemical bonds using a water molecule.
- Glycosidic bonds form between monosaccharides in carbohydrates.
- Ester bonds form between glycerol and fatty acids in triglycerides.
- Peptide bonds form between amino acids in proteins.
- Phosphodiester bonds form between nucleotides in nucleic acids.
- DNA is a double helix with complementary base pairing (A-T, C-G) held by hydrogen bonds.
- Semi-conservative DNA replication involves DNA helicase and DNA polymerase.
← Back to Biology AQA A-Level Specification · All Biology Topics