Stanmore College Interview Presentation

Introduction to Biological Molecules

Lyndsae Drury Biology Lecturer

Biological molecules

• 1. Water

• 2. ions

• 3. Sugars, Carbohydrates

• 4. Proteins

• 5. Lipids

Carbohydrates

Carbohydrates contain 3 elements:

• Carbon (C)• Hydrogen (H)• Oxygen (O)

• Carbohydrates are found in one of three forms:

• Monosaccharides

• Disaccharides (both sugars)

• Polysaccharides

• Monosaccharides

• General formula:.

• (CH2O)n where n is a number between 3 and 9. They are classified according to the number of carbon atoms. The monosaccharides you will have to know fall into these categories:

• C = 3 = triose

• C = 4 = tetrose

• C = 5 = pentose

• C = 6 = hexose

• Trioses: (e.g. glyceraldehydes), intermediates in respiration and photosynthesis.

• Tetroses: rare.

• Pentoses: (e.g. ribose, ribulose), used in the synthesis of nucleic acids (RNA and DNA), co-enzymes (NAD, NADP, FAD) and ATP.

• Hexoses: (e.g. glucose, fructose), used as a source of energy in respiration and as building blocks for larger molecules.

• All but one carbon atom have an alcohol (OH) group attached. The remaining carbon atom has an aldehyde or ketone group attached.

• Chain form:

• Mono Saccharides

• Examples of Disaccharides

• Sucrose: glucose + fructose,

• Lactose: glucose + galactose,

• Maltose: glucose + glucose.

• Maltose: glucose + glucose.

Disaccharides

Starch made of two polysaccharides

Differences between Glycogen and Amylopectin polysaccharides.The branches are formed by linking C # 1 to a C # 6 through an acetal linkages. In glycogen, the branches occur at intervals of 8-10 glucose units, while in amylopectin the branches are separated by 12-20 glucose units

Other Novel Polysaccharides

Chitin polysaccharide found in crabs and sea shells whereas Lignin in wood