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Chapter 2: The Chemistry of Life

Chapter 2: The Chemistry of Life. Remember metabolism?. Those reactions involve chemicals and chemistry! Chemistry: the science of matter What it’s made of What it does- reactions Democritus’ question…. Atoms- the basic unit of matter. VERY small- 100 million = 1 centimeter!

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Chapter 2: The Chemistry of Life

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  1. Chapter 2:The Chemistry of Life

  2. Remember metabolism? • Those reactions involve chemicals and chemistry! • Chemistry: the science of matter • What it’s made of • What it does- reactions • Democritus’ question…

  3. Atoms- the basic unit of matter • VERY small- 100 million =1 centimeter! • Subatomic particles • Protons (+) • Neutrons (0) • Electrons (-)* • Atomic number: # of protons • Mass number: # of protons + # of neutrons

  4. Element • A pure substance consisting of just one type of atom • Over 100 known- only about 24 commonly found in nature

  5. Isotopes • Atoms of the same element that differ in the number of neutrons • So they have a different what? • Same number of electrons means same chemical properties • Radioactive isotopes • Used to date fossils and rocks • Cure cancers/kill bacteria • Tracers- “label” a substance and follow it thru the body

  6. Chemical Compounds • A substance formed by the chemical combination of two or more elements in definite proportions • Formulas- ex: H20 and NaCl • Chemical/physical properties of compounds are very different than their individual elements

  7. Chemical Bonds • Chemistry- what matter “does”- depends on the forming/breaking of bonds • Involve valence electrons • 2 Main types of bonds • Ionic: transfer e- (ex: NaCl: Na+ and Cl- ions) • Covalent: share e- (ex: H2O) • Molecule- the smallest unit of most compounds

  8. Van der Waals forces • 1. covalent bond “sharing” isn’t always “equal” • 2. electrons are always in motion • …therefore there are always + and – regions of a molecule • Van der waals forces = intermolecular forces between + and – regions of molecules that attracts them together

  9. http://www.youtube.com/watch?v=OoYeIsSkafI

  10. 2-3 Carbon Compounds • Organic chemistry: the study of all compounds with bonds between C atoms • 4 macromolecules • Carbohydrates • Lipids • Nucleic acids • Proteins

  11. Why is C so important? • 4 valence electrons • How many bonds can it make? • 4! • Can bond with other carbon atoms • Long chains • Rings • Can form a variety of structures

  12. Macromolecules • What does “macromolecule” mean? • “giant” molecule • Monomers: small individual molecules • Polymer: a bunch of smaller monomers together • This process called: polymerization

  13. Carbohydrates • C, H & O • Living things use it for energy and structural purposes (plants) • Monomer: monosaccharides • Polymer: polysaccharides

  14. Carb Examples: • Animals: • Starch and glucose- store excess sugar • Fiber (from plants) helps with digestion • Plants: • Cellulose- rigidity and strength (ex: paper!) • Plant starch- store excess sugar Carb N. Ergy!

  15. Lipids • C and H • Fats, oils, waxes • Store energy in living things • Makes up waterproof membranes (ex: in cells) • Steroids

  16. Lipids are NOT polymers • Structure: • A glycerol molecule • 3 fatty acid chains • Saturated fatty acids: single bonds btwn Cs • maximum # H atoms possible • Unsaturated fatty acids: at least one double bond btwn Cs • Polyunsaturated: two or more double bonds btwn Cs

  17. Lipids Examples • Saturated (mostly solids): butter, waxes • Unsaturated (mostly liquids): olive oil • Polyunsaturated (mostly liquids): cooking oils like canola oil

  18. Nucleic Acids • H, O, N, C and P • Store and transmit genetic material • DNA and RNA • Monomer: nucleotides • Made up of: 5C sugar, phosphate group, N base • Polymer: nucleic acid • Covalent bonds

  19. Proteins • N, C, H and O • Regulates cell processes/ rates of reaction • Transport substances in/out of cells • Growth and repair of muscles and bone • Fight diseases

  20. Proteins (continued) • Monomers: amino acids (aa) • Amino group • Carboxyl group • R group side chain (unique) • 20+ found in nature

  21. Protein Structure • 4 Levels of organization: • Primary- sequence of aa form a chain • Secondary- aa form either a twist or folds within the chain • Tertiary-the chain itself twists/folds • Quaternary-how chain interacts with other chains • Attractive forces at work: • Van der waals forces • H- bonds • Peptide bonds

  22. Water! • 75% of earth is water! • 60% of the human body is water! • 70% of your brain is water! • You will die in a few days without water!

  23. 2-2 Properties of Water • Density • Polarity • Cohesion • Adhesion • High specific heat

  24. Density • Mass per unit volume • Water expands when frozen • Ice is less dense than water • What does this mean? • Why is this important in nature?

  25. Density Rainbow Test • At your lab tables, work with your group to make your hypothesis… • Place the following substances in order from MOST dense to LEAST dense. • Corn syrup • Water • Vegetable oil • Dish soap • Alcohol • Honey

  26. Check your hypothesis…were you correct?

  27. Polar • Uneven distribution of electrons between O and H atoms • O has 8 protons • H has only 1 proton • Covalent bonds

  28. Hydrogen bonds • attraction between H and an electronegative atom (like O!)

  29. Cohesion • The ability of water molecules to “stick together” • Surface tension *Jesus Christ lizard!

  30. Adhesion • The ability of water molecules to “stick” to other surfaces • Ex: capillary action in plants

  31. High Specific Heat • Water takes a long time to heat up and cool down • Have you ever gone surfing in Oct? Swimming in April?

  32. Mixtures • Mixture- 2 or more elements physically but not chemically combined • What does this mean? • Ex: salt and pepper • Ex: gases in the atmosphere

  33. Solutions and Suspensions • 2 types of mixtures: • Solutions: when the molecules of a mixture are evenly distributed • Solute: substance being dissolved • Solvent: usually water • Suspensions: a mixture of water and nondissolved material • These materials are “suspended” in the mixture

  34. Acids, Bases and pH • A water molecule can react to form ions • H2O  H+ + OH- • (Water  H ion + hydroxide ion) • # of H+ ions = # of OH- ions (water is” neutral”) • pH: concentration of H+ ions in a solution

  35. pH Scale • Scale from 1 to 14 • Water is neutral: pH of 7 • Acids: any compound that forms H+ ions in a solution • 1-6 on the scale • Bases: any compound that forms OH- ions in a solution • 8-14 on the scale • aka: alkaline solutions

  36. pH Buffers • Fluids in human body must be between 6.5 and 7.5 • Sharp increases or decreases will effect chemical reactions • So we must maintain internal conditions… • Hmm, what is THAT called? • Buffers: weak acids/bases that can react with strong acids/strong acids/bases to prevent sharp changes in pH

  37. 2-4 Chemical Reactions and Enzymes • Chemistry: • what things are made of • WHAT THEY DO! • This depends on chemical reactions! • Chemical reaction: a process that changes one set of chemicals into another • Mass and energy are conserved

  38. Chemical Reactions • Involve a change in the bonds • Quick or slow • Reactants (in)  products (out) • Ex: carbon dioxide as a waste product • CO2 + H2O  H2CO3 (carbonic acid) • H2CO3  H2O + CO2 (as we exhale)

  39. Energy in Reactions • All reactions release/absorb energy • Release energy- occur spontaneously • Absorb energy- require energy • Living things must have a source of energy • Plants- store energy from sun • Animals- digested good (metabolism!)

  40. Activation Energy • Activation energy: the energy needed to get a reaction started • Ex: cellulose will react with oxygen and burn • So why don’t our books burst into flames?

  41. Enzymes • Specific type of proteins • Some vital reactions take a long time to start • Catalyst: a substance that speeds up a chemical reaction • Lowers the activation energy • Enzymesare biological catalysts! • Speed up chemical reactions in cells • Specific!

  42. Why is this important? • Carbonic acid example • Too much CO2 in blood will kill you • Enzyme (carbonic anhydrase) speeds up reaction so it happens right away

  43. How enzymes work… • Must form an enzyme-substrate complex • Substrate = reactants • Substrate meet at active site • “lock and key” = very specific • Lowers activation energy needed for reaction to occur

  44. Enzyme Action 2. enzyme-substrate complex 1. reactants/substrates 3. *activation energy lowered *chemical reaction occurs active site 5. enzyme available for use again 4. products produced

  45. Regulation of Enzyme Activity • Affected by changes in temp., pH, etc. • Proteins can turn enzyme on/off • Roles: • Regulate chemical pathways • Make materials • Release energy • Transfer information

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