CHEMISTRY OF LIFE

1. CHEMISTRY OF LIFE

2. BIOLOGY-THE STUDY OF LIFE

3. The Chemistry of Life I. Organization of Atoms • Bonds • Water Molecules • Classification of Compounds V. Compounds found in living things.

4. I. Organization of Atoms • Atom- the smallest unit of matter that cannot be broken down by chemical means. • Protons- positive charge, located in the nucleus. • Neutrons- no charge, located in the nucleus. • Electrons- negative charge surrounding the nucleus in a cloud.

5. I. Organization of Atoms • Element- a pure substance made of only one kind of atom. • Compound- a substance made of the joined atoms of two or more different elements. Ex. NaCl (Sodium Chloride) • Molecule- a group of atoms held together by covalent bonds.

6. I. Organization of Atoms • Ion- an atom or molecule that has gained or lost one or more electron. Ions have an electric charge because they contain an unequal number of electrons and protons. • Positive charge- atom that has lost an electron. • Negative charge- atom that has gained electrons.

7. II. Bonds • Ionic Bonds- when ions of opposite charges interact. Ex. Sodium chloride—an atom of sodium is unstable—only 1 electron in the outer shell (valence electron). An atom of chlorine is unstable because it has 7 valence electrons. The atoms are readily attracted to each other.

8. II. Bonds • Covalent bonds – form when two or more atoms share electrons. (very strong bonds --“super glue”) • Hydrogen bonds – a weak chemical attraction between polar molecules. Ex. A water molecule—H2O.

9. III. Water Molecules • The electrons in a water molecule are shared by oxygen and hydrogen atoms. B. A water molecule has positive and negative ends, thus polar.

10. III. Water Molecules C. Particles are able to dissolve readily in water due to its polarity. Thus, the “universal solvent”.

11. III. Water Molecules D. Cohesion – an attraction between substances of the same kind. The hydrogen bonds between water molecules cause the cohesion of liquid water molecules at the surface of water (like holding hands).—this attractions is “surface tension”

12. III. Water Molecules E. Adhesion – attraction between different substances. Ex. Water molecules moving upward through the stem of a plant.

13. III. Water Molecules F. Evaporative cooling – Water heats more slowly and retains heat longer. Organisms release heat through water evaporative cooling (sweat).

14. IV. Classification of Compounds • Organic- compounds containing carbon (with hydrogen). Ex. Plants, animals • Inorganic- compounds that do not contain carbon. Ex. Air, water, minerals

15. V. Compounds Found in Living Things

16. CHO CHO CHON CHONP CHO CHO CHON CHONP CHO CHO CHON CHONP CHO CHO CHON CHONP CHO CHO CHON CHONP

17. Carbohydrates • A key source of energy • Building blocks are simple sugars- monosaccharides (glucose & fructose) • Disaccharides • Polysaccharides

18. Lipids • Stored energy (mostly in animal-some plant seeds) • Nonpolar molecules • Fats, oils, steroids, and waxes • Phospholipids—make up the lipid bilayer of cell membranes

19. Proteins • Important for structural functions • Skin, ligaments, tendons, muscles, hair • Anitibodies, hemoglobin, hormones, enzymes • Building blocks are amino acids • 20 different amino acids are found in living things

20. Nucleic Acids • Contain all genetic, hereditary information • DNA, RNA • Building blocks are nucleotides