OCR Applied Science: 4.4 Large Complex Carbon Molecules

This PowerPoint presentation with worked examples and student activities covers: Topic 4.4 of Module 1: Science Fundamentals of the OCR Applied Science Spec.

Complex carbohydrates (starch, glycogen, cellulose)

• Carbohydrates found as monosaccharides, disaccharides, or polysaccharides (monomers, dimers or polymers)
• Monomers held together by glycosidic bonds to form dimers and polymers, via condensation reactions
• Monosaccharides include glucose, fructose and galactose
• Disaccharides include maltose, sucrose and lactose
• Polysaccharides include starch, glycogen and cellulose
• Cellulose is found in plant cell walls where it provides strength/support and pliability
• Starch and glycogen are energy sources

Proteins and peptides from amino acids

• Dipeptides are formed from two amino acids joined by a peptide bond, via a condensation reaction
• Polypeptides are chains of amino acids joined by peptide bonds
• Proteins/polypeptides have physiological or functional roles, including enzymes, carrier proteins in the plasma membrane, and structural roles, including collagen and elastin fibres in connective tissue

Lipids from fatty acids, glycerol and phosphorus compounds

• Monoglycerides, diglycerides and triglycerides are esters of fatty acids and glycerol
• An ester bond forms between each fatty acid and the glycerol, via condensation reactions
• Phospholipids contain glycerol plus two fatty acids and a phosphate group
• Lipids act as an energy source within cells, as an insulation layer around animal organs, in the myelin sheath (found around some nerve fibres/axons) to increase speed of nerve transmission
• Phospholipids form a bilayer in the plasma membrane

Protein synthesis (transcription, translation) RNA, messenger, ribosomal and transfer

• The nucleic acids, DNA and RNA, are polymers of nucleotides
• Peptide bonds form between amino acids to create polypeptide chains/proteins
• Recall a simple description of protein synthesis