Summary Unit 1 - Biological molecules

Topic 1: Biological Molecules

Contents (checklist)
1.1 Monomers and polymers ..................................................................................................................2
Monomers and polymers ....................................................................................................................... 2
Condensation and hydrolysis reactions ................................................................................................. 2
1.2 Carbohydrates ..................................................................................................................................3
Monosaccharides and disaccharides ..................................................................................................... 3
Isomers of glucose: - and -glucose .................................................................................................... 3
Polysaccharides ...................................................................................................................................... 4
Biochemical tests ................................................................................................................................... 5
1.3 Lipids ................................................................................................................................................6
Triglycerides ........................................................................................................................................... 6
Phospholipids ......................................................................................................................................... 6
Saturated & unsaturated fatty acids...................................................................................................... 6
Emulsion test for lipids .......................................................................................................................... 6
1.4.1 Proteins: general properties of proteins..........................................................................................7
Amino acids, dipeptides and polypeptides ............................................................................................ 7
Structural levels of proteins and the role of bonds ............................................................................... 7
Biuret test for protein ............................................................................................................................ 7
1.4.2 Proteins: many proteins are enzymes .............................................................................................8
Introduction to enzymes ........................................................................................................................ 8
Factors affecting rate of enzyme-controlled reactions ......................................................................... 8
1.5.1 Nucleic acids: structure of DNA & RNA..........................................................................................10
Function of DNA & RNA .......................................................................................................................10
Structure of DNA & RNA nucleotides and polymers............................................................................10
Maths ...................................................................................................................................................10
1.5.2 Nucleic acids: DNA replication ......................................................................................................12
Process of DNA replication ..................................................................................................................12
Evidence for semi-conservative replication (Meselson and Stahl) ......................................................12
1.6 ATP .................................................................................................................................................13
The structure of adenosine trisphosphate (ATP) .................................................................................13
ATP/ADP hydrolysis and condensation ................................................................................................13
The properties of ATP make it a suitable immediate source of energy ..............................................13
1.7 Water .............................................................................................................................................14
How hydrogen bonding occurs between water molecules .................................................................14
Properties of water that are important in biology ..............................................................................14
1.8 Inorganic ions .................................................................................................................................15

, For more A Level Biology notes, tutorials and webinars, visit biologywitholivia.co.uk

1.1 Monomers and polymers
Monomers and polymers
• Monomer: small, single molecule, many of which can be joined together to form a polymer
• Polymer: large molecule made up of many similar / identical monomers joined together

Condensation and hydrolysis reactions
A condensation reaction:
• Joins 2 molecules together
• Eliminates a water molecule
• Forms a chemical bond e.g. glycosidic bond


A hydrolysis reaction:
• Separates 2 molecules
• Requires addition of a water molecule
• Breaks a chemical bond

Exam tip: to get full marks for a diagram of a condensation or hydrolysis reaction, you need to include the
H2O molecule that is added or removed




2