Chemical basis of Life

1. Chemical basis of Life Please Take out your notebooks

2. Vocabulary • Atoms are made up of protons, electrons, and neutrons. • Elements are pure substances that consists entirely of one type of atom. • Compound is a substance formed by the chemical combination of two or more elements in definite proportion. • Molecule is the result of atoms that are joined together by covalent bonds.

3. Bonding • Ionic bonds are formed when one or more electrons are transferred from one atom to another. • Covalent bonds are formed when electrons are shared between atoms.

4. Atoms – the basic unit of matter • made up of subatomic particles • protons (positive charge) • neutrons (no charge) • electrons (negative charge) • protons and neutrons form nucleus • have about the same mass • electron, 1/1840 the mass of a proton • Atoms have equal numbers of protons and electrons-so an atom is neutral

5. Elements – contain one type of atoms • Periodic Table of Elements • Atomic Number – number of protons • Atomic Mass – number of protons + neutrons

6. Elements you need to know • C • Ca • Cl • F • Fe • H • I • K • Mg • N • Na • O • P • S • Zn

7. Isotopes • Isotopes – atoms with same number of protons, but different numbers of neutrons (same element) • identified by mass number • same number of protons=same properties • Radioactive Isotopes – nuclei unstable • break down at a constant rate over time • radiation can be dangerous • have practical uses • age rocks • treat cancer • kill bacteria

8. Chemical Compounds • Chemical compound – the chemical combination of 2 or more elements in definite proportions. • shown by a chemical formula, H2O, NaCl • Compounds are held together by chemical bonds. • involves electrons in outer shell • Types of bonds: • Ionic – one or more electrons moves from one atom to the other • forms ions, one atom with a (+) charge and one with a (-) charge • NaCl- salt • Covalent – atoms share electrons • the electrons travel in the orbitals of both atoms • form a molecule • H2O - water

9. Van der waals forces • When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. • Like H2O molecules which creates surface tension • Not as strong as ionic or covalent bonds

10. Penny Lab • Problem: How many drops of water can a penny hold?

11. Properties of Water • Water is the most abundant compound in living things. • Polarity – H2O, oxygen atom pulls electrons to it because it has 8 protons and H has 1 • so the O end of the molecule has a slight negative charge • the H end of the molecule has a slight positive charge • because water molecules are polar, they can attract each other

12. The properties of water • Hydrogen Bond- a H atom on one water molecule is attracted to the O atom on another water molecule • Cohesion-attraction between molecules of the same substance • Adhesion-attraction between molecules of different substances

14. Types of Mixtures made with water • Solution-ions dispersed in water (NaCl) evenly • Solute- (solid) the substance that is dissolved (salt) • Solvent- (liquid) dissolves the solute (water) • The polarity of water gives it the ability to dissolve substances. • Water is the greatest solvent on earth. • Suspensions-mixtures of water and non-dissolved materials • blood, mostly water with dissolved and undissolved particles

15. PH scale • pH scale – indicates the concentration of H+ ions in solution • range 0-14 • neutral is 7, H+ and OH- ions are equal, pure water • lower pH (0-6), greater acidity • higher pH (8-14), more basic/alkaline • acid-higher concentration of H+ than pure water • base-lower concentration of H+ than pure water, more OH- ions

16. Buffers • Buffers-weak acids or bases that can react with strong acids or bases to prevent, sharp, sudden changes in pH. • controlling pH in organisms is important to maintain homeostasis • 6.5-7.5 (pH of Blood), affects chemical reactions in cells

17. Carbon Compounds • Organic Chemistry – the study of all compounds that contain bonds between carbon atoms. • Carbon has 4 valence electrons – outside orbital • each can form a strong covalent bond • bonds with many elements including other carbon atoms • forms carbon rings and chains, millions of complex structures • no other element comes close

18. Macromolecules – giant molecules • Are made from many thousands of smaller molecules • formed by polymerization • monomers (smaller units) form polymers

19. 4 groups of organic compounds • carbohydrates • lipids • nucleic acids • proteins

20. Carbohydrates – sugars and starches • carbon, hydrogen, oxygen, 1:2:1 ratio • main source of energy for living things • plants and some animals; for structure • extra sugar stored as complex carbohydrates known as starch

21. monosaccharides: simple sugars-glucose, galactose/milk, fructose/fruit • polysaccharides: many monosaccharides linked together (starch and cellulose)

22. Lipids – fats, oils and waxes • not soluble in water • mostly C and H atoms • can store energy • important parts of membranes and waterproof coverings • steroids/chemical messengers • form when glycerol combines with a fatty acid

23. Types of lipids • Saturated/fatty acid contains the maximum number of H atoms (solid-butter) • all C atoms are joined to another C atom by a single bond • Unsaturated/fatty acid at least one C-C double bond, not max. number of H atoms attached (olive oil-liquid at room temp.) • Polyunsaturated/fatty acids with more than one double bond • (corn oil, sesame, canola, and peanut oil)

24. Nucleic Acid – store and transmit genetic info • macromolecules of H, O, N, C, P • polymers of nucleotides/joined by covalent bonds • nucleotide – 3 parts • 5-carbon sugar • phosphate group • nitrogenous base • two kinds • RNA, ribonucleic acid (contains sugar ribose) • DNA, deoxyribonucleic acid (deoxyribose)

25. Proteins • macromolecules of N, C, H, O • polymers of amino acids • very diverse molecule • 20 found in nature – amino acids • all can join to form covalent bonds • instructions for arranging amino acids into proteins are stored in DNA

26. Each protein has a special job! • Control rate of reactions • Regulate cell processes • Form bones and muscle • Transport substances into or out of a cell • Help fight disease • Protein shape is very important