M 3.2 Biological Molecules - Lipids, Nucleic Acids PDF

M 3.2 (iii) Biological molecules - lipids, nucleic acids  Learning Objectives: Outline the classification system for lipid molecules. Describe the basic structure of fatty acids and explain their role in the body. Consider the structure of triglycerides and explain their...

M 3.2 (iii) Biological molecules - lipids, nucleic acids  Learning Objectives: Outline the classification system for lipid molecules. Describe the basic structure of fatty acids and explain their role in the body. Consider the structure of triglycerides and explain their role in cell membranes. Discuss pyrimidines and purines and the formation of nucleosides, nucleotides and ATP. Outline the basic structure of the polynucleotides, RNA and DNA.  Lipids - Background Heterogeneous group of compounds Consist mainly of carbon and hydrogen (hydrophobic) few oxygen Soluble in non-polar solvents e.g. ether, chloroform Loading… Generally insoluble in water  Biologically important lipids Fats Phospholipids Steroids Carotenoids Waxes  Role of Lipids Energy Cell Stores Membranes Loading… Hormones Vision Protection  Triacylglycerols (fats) – Most abundant lipids in living organisms – When metabolized, yield twice as much energy as carbohydrates – Carbohydrates and proteins can be transformed by enzymes into fats Triacylglycerol - the main storage lipid  Fatty Acids Saturated fatty acids contain maximum possible number of hydrogen atoms Unsaturated fatty acids include one or more adjacent pairs of carbon atoms joined by a double bond Monounsaturated fatty acids—one double bond Polyunsaturated fatty acids—more than one double bond  Phospholipids – Amphipathic lipids – Two ends differ physically and chemically – Uniquely suited to function as fundamental components of cell membranes A phospholipid and a phospholipid bilayer A phospholipid and a phospholipid bilayer Loading…  Carotenoids – Orange and yellow plant pigments – Classified with lipids – Play a role in photosynthesis – Consist of isoprene units – Animals convert to vitamin A  Isoprene- derived compounds A - Isoprene subunit D B – b - carotene A C – Point of cleavage C D – Vitamin A E – Retinal E B  Steroid s – Carbon atoms in four attached rings – Consist of isoprene units – Cholesterol, bile salts, etc. – Involved in regulating metabolism  Nucleic Acids – Transmit hereditary information – Determine what proteins a cell manufactures – Two classes found in cells Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) – Polymers of nucleotides  Components of Nucleotides 1. Five-carbon sugar 1. Deoxyribose (DNA) 2. Ribose (RNA) 2. One or more phosphate groups 3. Nitrogenous base of either a double-ring purine or a single- ring pyrimidine Nucleotide – Nitrogen bases DNA - double stranded Helix Two chains  RNA Nucleotides are joined by phosphodiester linkages RNA is single stranded i.e. One chain Gene Expression Other Nucleotides – Adenosine tri phosphate (ATP) High energy currency of the cell Other Nucleotides – cyclic AMP Cyclic adenosine monophosphate (cAMP) Cell signaling Transfers the effects of hormones into cells e.g. glucagon and adrenaline, which cannot pass through the plasma membrane. It is also involved in the activation of protein kinases. Overview of Biomolecules  Reading Chapter 3 ‘The Chemistry of Life’ Organic Compounds Solomon 11th Ed. Lipids: p56- 59 Nucleic Acids: p68 - 69