1. Building Blocks of Life An Introduction

2. Carbon—The Backbone of Biological Molecules Carbon is unparalleled in its ability to form large, complex, and diverse molecules Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds

3. Carbon atoms can form diverse molecules by bonding to four other atoms Electron configuration determines the kinds and number of bonds an atom will form with other atoms With four valence electrons, carbon can form four covalent bonds with a variety of atoms ◦makes large, complex molecules possible

4. The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the “building code” that governs the architecture of living molecules

5. Macromolecules Within cells, small organic molecules are joined together to form larger molecules Macromolecules are large molecules composed of thousands of covalently connected atoms

6. polymers built from monomers Monomers build polymers linked together by covalent bonds Three of the four classes of life’s organic molecules are polymers: ◦Carbohydrates ◦Proteins ◦Nucleic acids ◦Lipids

7. The Synthesis and Breakdown of Polymers Monomers form larger molecules by condensation reactions called dehydration reactions Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction

8. Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Dehydration reaction in the synthesis of a polymer Longer polymer Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer

9. Carbohydrates Sugars and sugar polymers Monosaccharides ◦Simple sugars ◦glucose Carbonyl group Hydroxyl group

10. Carbohydrates Disaccharides ◦2 or more monosaccharides joined by glycosidic linkage, covalent bond by dehydration reaction ◦Glucose + fructose sucrose

11. Carbohydrates Storage ◦Plant starch ◦Stored energy can be broken down by hydrolysis into glucose ◦Animal polysaccharide  Glycogen ◦ Stored in liver and muscles ◦ Used for short term energy

12. Carbohydrates Structure ◦Cellulose: cell walls  Requires an enzyme for animals to break it down ◦Chitin: exoskeleton of arthropods and fungi

13. Lipids Fats, oils, waxes ◦Mix poorly with water ◦Fats  Large molecules of glycerol and fatty acid chains connected by dehydration

14. Lipids Cell Membranes ◦Phospholipid bi-layer

15. Proteins Polymer of amino acids called polypeptides Functions ◦Enzymes ◦Storage of amino acids ◦Hormones ◦Motor ◦Defense ◦Transport ◦Receptors for chemical stimuli ◦structure

16. Proteins Amino acids ◦20 amino acids from 1000’s of proteins ◦Side chains “R” determines the properties  Hydrophillic:polar  Hydrophobic: non polar  Hydrophillic: electric charge

17. Proteins Structure ◦1°  Linear chain

18. Proteins 2° ◦Alpha helix: hair ◦β pleated sheets: spider web ◦Held together by hydrogen bonds between amino groups

19. Proteins 3° ◦Interactions between side chains “R”  Hydrogen bonds  Ionic bonds  Disulfide bonds  Van der Waals

20. Proteins 4° ◦Aggregation of polypeptide subunits  Collagen  hemoglobin

21. Proteins Denaturation ◦Weak chemical bonds and interactions can be destroyed  Heat  pH

22. Nucleic Acids Polymer of nucleotides ◦DNA and RNA