Water and Biological Molecules

1. Water and Biological Molecules

2. I. The Importance of Water to Life • 71 % of Earth’s surface; 66 % of weight of human body

3. B. Important properties of water 1. Required/generated by many cellular reactions (breaking down food) 2. Important solvent—hydrogen bonds with polar or charged molecules (NaCl) 3. Important for insulating Earth, and for cooling living organisms by sweating • Cohesion and surface • tension – allows water to • move up a tree in cells; • allows insects to walk • on water.

4. II. Carbon Is a Central Element in Life A. Carbon is the starting point for biological molecules 1. Four electrons in outer shell; can make four bonds (covalent, stable) 3. Long Chains 4. Double bonds 5. Rings

5. The Molecules of Life (Organic Molecules): Carbohydrates. Lipids, Proteins, and Nucleic AcidsA. Carbohydrates

6. 1. Monomer (or single unit)—rings of C, H, and O (glucose, C6H12O6) called monosaccharides • a) Examples: glucose, fructose, galactose, ribose, deoxyribose

8. 2. Polymers are chains of monomers created by chemical reaction called condensation (also called dehydration synthesis) a) Simplest polymer is disaccharide; examples: sucrose, lactose, maltose 3. Condensation reactions can be reversed; hydrolysis (digestion in our guts -)

9. 4. Simple sugars on food labels are mono and disaccharides: 5. Complex carbohydrates on food labels: long chains of monomers called polysaccharides: a) Starch, main form of energy storage

10. b) Glycogen, primary short-term energy storage in animals, released as glucose into the bloodstream when needed.

11. c) Cellulose, functions to provide structure to plants; indigestible to mammals (fiber on food label) d) Chitin, functions in external skeleton of arthropods e) The general formula for carbohydrates is (CH2O)n

12. B. Lipids 1. Common characteristics of lipids: composed of C, H, and O, but insoluble in water. 2. Major function: Energy storage and insulation, but also function as hormones and the outer lining of all cells.

13. 3. Glycerides—composed of glycerol and fatty acids (For example, triglycerides). a) Make up 90 percent of lipid in food

15. b) Difference between • saturated and unsaturated • fatty acids: Bonds

17. c) Saturated fatty acids are usually solids like butter. d) Unsaturated fats are usually liquid, like oils

18. 4. Steroids • Composition: Usually consists of chains of rings • Examples: Cholestorol, Bile salts, Vitamin D, Sex Hormones (estrogen and testosterone)

19. Phospholipids a) Composition: b) Makes up cell mbranesme

21. C. Proteins 1. functions: promote chemical rxns (enzymes), Provides structure (skin, bones, etc.), provides defense (antibodies), and more. 2. Composition: monomers = amino acids

22. Polymers = polypeptides

23. D. Nucleic Acids • 1. Function—provides information for structure of proteins 2.Composition—nucleotides:

24. DNA = deoxyribonucleic acid -- Double strand of nucleotides • In nucleus • Controls cell activities • Stores heredity info • Directs production of proteins • Makes up genes on chromosomes • Controls heredity

25. RNA – ribonucleic acid • -- Single strand of nucleotides • Helps DNA make proteins • Found all around the cell

26. Recap