Chapter 2 The Chemistry of Life

1. Chapter 2The Chemistry of Life

2. Life depends on chemistry. Millions of chemical reactions occur in living organisms every day. Organisms rely on chemical reactions in order to function. Food must be broken down, gases must be exchanged, molecules must be built.

3. Levels of Organization

4. Levels of Organization • http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

5. Section 2-1The Nature of Matter

6. Atoms • Atom - Basic unit of matter. • All matter - including living things - is made up of groups of atoms “stuck” (bonded) together.

7. Elements • Element – a kind or “species” of atom. There are >100 elements or kinds of atoms. • Living things are mostly made of six elements: C, H, O, N, P, S (in order of most to least common) • Carbon • Hydrogen • Oxygen • Nitrogen • Phosphorus • Sulfur

8. Elements • What element is… • N? • C? • S? • P? • H? • O?

9. Chemical Compounds • Compound – a substance formed by the chemical bonding of two or more elements • Written as chemical formulas. Letter = element, small number = how many atoms of the element • Example: Water or H2O = 2 hydrogen atoms and 1 oxygen atom • Example: Glucose or C6H12O6 = 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms

10. Chemical Compounds • How many atoms of each element are in these compounds? • (Nitric acid) HNO3 • (Salt or Sodium Chloride) NaCl • (Potassium Phosphate) KPO4 • (Carbon dioxide) CO2 • (Sulfur dioxide) SO2 • (Glycerol) C3H8O3

11. CHECKPOINT • A living thing is made up of cells, which are made up of ___________, which are made up of ___________, which are different kinds of ___________.

12. Chemical Reactions • Chemical reaction – atoms break and/or make bonds to form different compounds • Reactants – elements or compounds that enter into a reaction • Products – elements or compounds that are produced by the reaction Example: 2H2O2 2H2O + O2 (reactant) (products) Example: 2K + Cl2 2KCl (reactants) (product)

13. Chemical Reactions • Identify the products and reactants in each of these reactions. • 8 Fe + S8 -> 8 FeS • 2 H2O -> 2H2 + O2 • Zn + 2 HCl -> ZnCl2 + H2 • NaCl + AgNO3 -> NaNO3 + AgCl • C10H8 + 12O2 -> 10CO2 + 4H2O

14. Section 2-3 Organic Molecules -Carbon Compounds

15. The Chemistry of Carbon • Organic molecules - carbon based molecules that make up living organisms • Carbon forms the backbone or basic structure of all large organic molecules, because it is abundant and flexible. • Can bond with up to 4 other atoms at once. • Can form single, double or triple bonds. • Bonds easily with other carbon atoms to form the backbone of large organic molecules. • Can bond with many different elements such as H, O, P, S, N.

16. Four Groups of Organic Molecules • Most molecules in cells are so large they are called macromolecules or “giant molecules.” • Most macromolecules = polymers, which are chains of repeating smaller molecules called monomers. • Polymerization – Joining monomers together to make a polymer • Organic molecules are classified into 4 groups: 1. Carbohydrates 2. Lipids 3. Nucleic acids 4. Proteins

17. Carbohydrates • Elements: C, H, O • Examples: Sugars and starches • Functions: • Main source of energy for living things • Used for structure in plants and some animals • Monomer – monosaccharide (simple sugar, like glucose), Polymer – polysaccharide (complex carbohydrate, like starch)

18. Nucleic Acids • Composition: C, H, O, N, P • Examples: DNA and RNA • Function: Store and transmit genetic information • Monomer – nucleotide / Polymer – nucleic acid

19. Proteins • Composition: C, H, N, O • Examples: enzymes, cell membrane proteins, muscle proteins • Functions: • Control rate of chemical reactions • Regulate cell processes • Structure • Transport other substances • Monomer – amino acid / Polymer – polypeptide or protein • Structure or shape of a protein is extremely important to its function.

20. Lipids • Composition: mostly C and H and some O • Examples: Fats, oils, waxes • Functions: • Energy storage • Compose parts of biological membranes and waterproof coverings • Generally not soluble in water • No monomers or polymers.

21. Section 2-4:Chemical Reactions and Enzymes

22. Energy in Reactions • Chemical reactions don’t happen automatically. (see graphs) • Activation energy – the energy needed to get a reaction started

23. Enzymes Activation energy without enzyme • Some reactions are too slow or require too much energy to happen in cells… unless they have help. • Enzymes = proteins that speed up chemical reactions that take place in cells • Enzymes work by lowering the activation energy of the reaction, making it easier which makes it faster. Activation energy with enzyme Course of Reaction

24. Enzymes and Reactions • Think cars: • Which car finishes the race first, the one that took MORE gas before it would start, or the one that took LESS?

25. Enzyme Action • Catalyst = A chemical that speeds up a reaction without being used up or altered. • Enzymes are biological catalysts. • Each enzyme = unique shape = only binds to a specific reactant = only catalyzes one kind of reaction.

26. Enzyme Action Enzyme Substrates Products Active site Substrates bind to enzyme at active site. Products are released. Enzyme is available again. Chemical reaction occurs and substrates are changed to products.

27. Enzyme Action Product is released. Enzyme is available again. Reactants bind to the enzyme at the active site. Chemical reaction changes reactants to products.

28. Enzyme Animations http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html http://www.lpscience.fatcow.com/jwanamaker/animations/Enzyme%20activity.html http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__enzyme_action_and_the_hydrolysis_of_sucrose.html http://www.kscience.co.uk/animations/model.swf http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter2/animation__protein_denaturation.html

29. Effects of Altered pH or Temperature on Enzyme Action Chemical reaction can’t occur. Reactants don’t get changed to products. A change in the enzyme prevents reactants from binding. Shapes don’t match. Summary: An enzyme outside of its OPTIMAL environment does not function as well, which means it will not make the reaction proceed as QUICKLY.

30. pH and Buffers • pH scale – measurement system of how acidic or basic something is / ranges from 0 –14 • pH 7 = neutral (pure water) • pH < 7 = acid (tomatoes, lemons) • pH > 7 = base (soaps, cleaners) • pH in human cells must be kept between 6.5 and 7.5 or chemical reactions will be affected. • pH and temperature affect how well enzymes work because they change the shape of the protein.

31. Enzyme Thought Problems • 1. Two plants live in a 35 degree environment. Which one is more likely to survive and reproduce: the one whose enzymes work best at 30 degrees, or the one whose enzymes work best at 20 degrees? Why? • 2. Your body temperature is 98.6 degrees, and your body’s pH is close to 7. At what temperature and pH do you think most human enzymes probably work? • 3. Your cells can live at 90 degrees. The cells of bacteria from Antarctic ice, however, die at 70 degrees. Why? • 4. Your body must maintain homeostasis: you must keep your body at a constant temperature and pH. Why is this essential to your survival?

32. Enzyme Thought Problems • 5. At which pH do each of these enzymes perform optimally (best)? At which pH do these enzymes become denatured? • 6. Which enzyme is probably found in a human stomach?