Chapter 2: the chemistry of life

1. Chapter 2: the chemistry of life General Biology 2010-2011

2. Section 2.1 The Nature of Matter Atoms are the basic unit of all matter. • Protons and Neutrons have about the same mass • Protons are positively charged. • Neutrons are neutral, they have no charge at all.

3. What is Science? • A little history! • 2500 years ago: • Greek philosopher Democritus thought that there was a limit on how much matter could be broken apart. • Was he correct?

4. Electrons are negatively charged particles. • Electrons are smaller than a proton,   - An electron is 1/1840 the mass of a proton. • They are attracted to the positively charged protons. • Electrons have a lot of energy and are always in motion.

5. Atoms have an equal amount of electrons and protons. • This balances the charge of the atom. • This results in no charge. • Key question – What three particles make up atoms?

6. Elements and Isotopes • Elements are made up of only one kind of atom: •  Elements are a pure substance: • carbon (C) • sodium (NA) •  The number of protons = atomic number

7. The atomic number of carbon: • 6 protons • 6 neutrons • _______ = mass number of carbon (carbon 12) • Isotopes • Same element with a different number of neutrons.

8. Example: Carbon always has 6 protons, but may have 6, 7 or 8 neutrons. •  Radioactive Isotopes • The nucleus of an atom breaking down over time is radioactive isotopes. • Radioactive isotopes: • can help determine the age of rocks and fossils. • treat cancer • can trace how substances move in organisms.

9. Key Question – How are all of the isotopes of an element similar? • Chemical Compounds • A compound is a formed substance from a chemical combination of two or more elements. • A chemical formula shows the number of each element in a compound. • Example: water H₂0

10. Physical properties of a compound are different then the properties of the elements that they came from. • Example: oxygen can be a gas or a liquid. •  Key Question – How do compounds differ from the elements in them? .

11. Chemical Bonds • Ionic Bonds – are formed when one or more electrons are moved, or transferred from one atom to another. • Covalent Bonds – when electrons are shared by atoms instead of being moved from one atom to the other.

13. The different types of covalent bonds are determined by how many electrons are shared. • Example: 2 electrons are shared – single bond • 4 electrons are shared - double bond • 6 electrons are shared – triple bond • Key Question: What are the main types of chemical bonds.

14. 2.2 Properties of Water (The Water Molecule H₂0) • Polar Molecule • Water is neutral • Positive charges on its 10 protons balance out the negative charges on its atom10electrons. • Oxygen s have 8 protons whereas a hydrogen has only 1 (there are 2 oxygen molecules in water)

15. Electrons in the water molecules are pulled toward the oxygen atoms. Oxygen on one end and hydrogen on the other. Resulting in: slight negative charge on the oxygen atom slight positive charge on the hydrogen end.

16. Hydrogen Bonds (polar molecules attract each other) •  Cohesion = attraction of molecules of the same substances. • Cohesion pulls water molecules together. •  Adhesion = an attraction of molecules of different substances. • Example: water sticking to the side of glass. • Heat Capacity = amount of heat energy needed to increase substances.

19. Because of the hydrogen bonds, it’s hard for water molecules to move faster. • This helps to regulate the temperature of lakes and oceans. • Key Question – How does the structure of water lead to its special properties?

21. Solutions and Suspensions • Solutions = mixture in a mixed substance is evenly spread out. • Suspensions = mixture of water and a non-dissolved material that do not settle out. • Acids, Bases, and PH • Ions – are water molecules that break apart Equation = H₂0 ↔ H⁺ + H0⁻

22. The pH Scale = concentration of H⁺ions in a solution (PH scale 0-14) • PH of 7 is where the H⁺and HO⁻ ions are equal • Example: water (PH of 7) • Acids = releases H⁺ ions in solution. PH below 7 would have a higher acidity. • Basis = compound that releases hydroxide (HO⁻). • PH values above 7. • Example: lie soap PH 11-14

23. Buffers = equalize or stop sudden changes in PH • Examples: Blood, they play a strong role in controlling homeostasis.

24. 2.3 Carbon Compounds • The chemistry of carbon • There are two reasons why carbon is so very important to living things. • The first reason is: • Carbon has four electrons available for bonding. • Can bond with many elements • Makes it possible to form the molecules of living things.

25. The second reason is that carbon atoms can bond with each other. • Carbon can make long chains, and form many different types of compounds. Key Question – What elements does carbon bond with to make up life’s functions?

26. Not in notes Carbon bonds with: • hydrogen, oxygen, phosphorus sulfur and nitrogen • this allows the formation of living things • living things are made from carbon and these other elements. • Carbon can also bond with each other • Resulting in an unlimited length Whale evolution timeline

27. Not in notes • These bonds can be • single, double, triple, covalent bonds or rings • This results in the ability to form millions of different large and complex structures.

28. Macromolecules = (carbon compounds) • Polymers - thousands or hundreds of thousands of smaller molecules that join together. • Monomers are smaller units that join together like links in a chain. (they form polymers) • Carbohydrates • Simple sugars

29. The four major groups of macromolecules are • Carbohydrates • Lipids (fats) • Nucleic acids • Protein • Key Question – What are the functions of carbohydrates?

30. Carbohydrates = compounds made up of carbon, hydrogen and oxygen • Are used as a main source of energy in living things. (the breakdown of sugars, glucose supply energy for cell activity). •  Starch is extra stored energy (glucose). • Give plants, some animals and other organisms structure (cellulose) cell wall of a plant.

31. Simple sugars = molecule called monosaccharide's (simple sugars) • Example: galactose (found in milk) • fructose (found in many fruits) • sucrose (table sugar): • Both fructose and sucrose • Complex Carbohydrates = macromolecules formed when simple sugars join together.

32. Animals store extra sugar called glycogen • Replaces low sugar in your blood • Gives muscles energy to move • Lipids – do not dissolve in water, and are made mostly of carbon and hydrogen atoms. • Store energy • Form biological membranes (cell membrane) • Waterproofing

33. Saturated fats and unsaturated fats have different types of carbon bonds. • Saturated fats are liquid at room temperature. • Example (olive oil) • Key Question – What are the functions of lipids? (fats)

34. Nucleic Acids • Macromolecules containing oxygen, nitrogen, carbon, and phosphorus • It stores and transmits genetic information • Key Question – What are the functions of nucleic acids?

35. Proteins • Macromolecules that contain nitrogen, carbon, hydrogen, and oxygen. • Proteins are polymers of molecules called amino acids. • Structure and Function • 20 different amino acids are found in nature.

36. C. Fields of Biology • Levels of Structure: • Amino acids are joined in a long chain according to the DNA instructions • Key Question – What are the functions of proteins?

37. 2.4 Chemical Reactions and Enzymes • Chemical Reactions • Is a process that change one set of chemicals with another. • Some use energy and some release energy • This produces chemical reactions in living things • Products are elements or compounds that come out of a chemical reaction. • Some bonds are broken and some are formed http://www.northland.cc.mn.us/biology/biology1111/animations/enzyme.swf

38. Key Question – What happens to chemical bonds during a chemical reaction? • Energy in Reactions • Chemical reactions involve change in energy. • This happens whenever chemical bonds are formed or broken.

39. Energy Changes • Chemical reactions that give off energy often happen automatically • Chemical reactions that take in energy need a source of energy to happen • Hydrogen reacts with oxygen to make water vapor: • 2H₂ + O₂ → 2HO₂

40. Energy Sources • Plants get their energy from trapping and storing the energy from sunlight. • Animals get their energy from eating plants or other animals.

41. Activation Energy • Chemical reactions that give off energy will not always happen by themselves. • Example: cellulose in paper can burn, but needs a match to do so. • It needs a reaction. • Energy is involved in all chemical reactions.

42. Key Question – How do energy changes affect whether a chemical reaction will happen? • Enzymes = chemical reactions that make life possible. • Natures Catalysts • A catalyst is a substance that speeds up the rate of a chemical reaction • Catalysts work by lowering the reactions activation energy.

43. The joining of carbon dioxide and water, which makes carbonic acid Co₂ + H₂O → H CO₃

44. Enzymes and Substrates • For a chemical reaction to take place: • Reactant must be hit with enough energy for bonds to break, and new bonds to form. • The enzyme has a breaking site that where reactants are brought together.

45. This site is called a substrate which bonds to the active site and weakens the chemical bonds.

46. Controlling how enzymes work • controlling chemical reactions • Making materials for cells • Giving off energy • Sending information

47. Temperature, Ph, and other molecules can affect how enzymes work. • How enzymes work best: • The temperature at 37 celcius. • Normal human body temperature • Certain PH values (example: enzymes in the stomach work best acidic solutions) http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

48. Enzymes are controlled y molecules that switch on or off. Key question – What role do enzymes play in living things and what affects their function?