Chapter 2: Chemicals of Life

1. Chapter 2: Chemicals of Life

2. A. Bonding • 1. Covalent Bonds • 2 or more atoms share electrons to form a molecule • No net charge due to equal number of + and – • Ex. water

3. Properties of Water Covalent bonding vs. Hydrogen bonding Hydrogen Bond Covalent Bond

4. A. Bonding • 2. Hydrogen Bonds • Weak bond between polar molecules

5. A. Bonding • 3. Ionic Bonds • Gained or lost one or more electrons • Charged due to unequal number of electrons or protons • Ex. NaCl

6. B. Properties of Water 1. High Heat Capacity • Water heats slow • Retains heat longer • Helps maintain homeostasis

7. B. Properties of Water 2. Universal Solvent Water is the solvent of Life! Solute– substance dissolved in a solvent to form a solution Solvent– fluid that dissolves solutes Example: Ice Tea – water is the solvent and tea and sugar the solutes

8. B. Properties of Water 3. Cohesion, Adhesion and Surface Tension • a. cohesion= water attracted to other water • molecules because of polar properties • ex. Forms drops or film • surface tension= water is pulled together creating the smallest surface area possible • b. adhesion= water attracted to other materials • ex. Getting wet, capillary action

9. B. Properties of Water 4. Capillary Action = Water molecules move due to adhesive and cohesive properties as a result of the original adhesion. Ex: Think water in a straw Ex: Water moves through trees this way

10. B. Properties of Water • 5. Water is a polar molecule. • Many substances will dissolve • Non-polar molecules will not dissolve

11. C. Classes of Organic Molecules: • What are the four classes of organic molecules? • Carbohydrates • Lipids • Proteins • Nucleic Acids

12. 1. Carbohydrates • Sugars • Carbo = carbon, hydrate = water; Oxygen • Functions: • Store energy in chemical bonds • Glucose is the most common monosaccharide • Monosaccharides • Disaccharides • Polyshaccharides

13. 1. Carbohydrates • Benedicts Test

14. 1. Carbohydrates • Iodine • Starch test

15. 2. Lipids • Structure: Greasy or oily nonpolar compounds • Functions: • Energy storage • membrane structure • Protecting against drying out. • Insulating against cold. • Absorbing shocks.

16. 2. LipidsSaturated and Unsaturated Fats • Unsaturated fats : • liquid at room temp • one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails • most plant fats • Saturated fats: • have only single C-C bonds in fatty acid tails • solid at room temp • most animal fats

17. 2. Lipids. • Phospholipids • Structure: Glycerol + 2 fatty acids + phosphate group. • Function: Main structural component of membranes, where they arrange in bilayers.

18. 3. Proteins • Structure: • Polypeptide chains • Consist of peptide bonds between 20 possible amino acids • Have a 3 dimensional globular shape

19. 3. Functions of Proteins • Enzymes speed up a chemical reaction • Structural materials • keratin (the protein found in hair and nails) • collagen (the protein found in connective tissue) • Specific carriers – • Carry materials across cell membrane, carry oxygen in blood

20. 3. Proteins: • Structure of Amino Acid • Hydrogen • Amino group • Carboxyl (acid) group • Variable R group specific to each amino acid

21. 4. Nucleic Acids • Two kinds: • DNA: double stranded can self replicate makes up genes which code for proteins is passed from one generation to another • RNA: single stranded functions in actual synthesis of proteins coded for by DNA is made from the DNA template molecule