1. The student is expected to: 4B investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules, 9A compare the structures and functions of different types of biomolecules, including carbohydrates, lipids, proteins, and nucleic acids and 9C identify and investigate the role of enzymes CHAPTER 2: THE CHEMISTRY OF LIFE

2. CHEMISTRY ORGANIC CHEMISTRY (contain carbon) INORGANIC CHEMISTRY (usually don’t contain carbon) BIOCHEMISTRY carbohydrates, lipids, proteins, nucleic acids (organic) water and carbon dioxide (inorganic)

3. Section 2-1: Atoms, Ions, and Molecules

4. Living things consist of atoms of different elements. An atom is the smallest basic unit of matter. An element is one type of atom. H O Hydrogen atom (H) Oxygen atom (O) Section 2-1: Atoms, Ions, and Molecules

5. –The nucleus has protons and neutrons. –Electrons are in energy levels outside nucleus. -Electrons are what are responsible for an element’s reactivity! -Elements with their outer energy level “full” are nonreactive. Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-) An atom has a nucleus and electrons. Section 2-1: Atoms, Ions, and Molecules

6. –water (H 2 O) O HH _ ++ A compound is made of atoms of different elements bonded together. Section 2-1: Atoms, Ions, and Molecules

7. –carbon dioxide (CO 2 ) A compound is made of atoms of different elements bonded together. –water (H 2 O) Section 2-1: Atoms, Ions, and Molecules

8. –many other carbon-based compounds in living things A compound is made of atoms of different elements bonded together. –water (H 2 O) –carbon dioxide (CO 2 ) Section 2-1: Atoms, Ions, and Molecules

9. Ions form when atoms gain or lose electrons. An ion is an atom that has gained or lost one or more electrons. –positive ions –negative ions Ionic bonds form between oppositely charged ions. Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron Section 2-1: Atoms, Ions, and Molecules

11. Atoms share pairs of electrons in covalent bonds. A molecule forms when two or more atoms are held together by covalent bonds. covalent bonds Oxygen atom (O)Carbon atom (C)Oxygen atom (O) Carbon dioxide (CO 2 ) –multiple covalent bonds –diatomic molecules Section 2-1: Atoms, Ions, and Molecules A covalent bond forms when atoms share a pair of electrons.

12. Section 2-1: Atoms, Ions, and Molecules

13. O HH _ ++ Life depends on hydrogen bonds in water. Water is a polar molecule. –Polar molecules have slightly charged regions. – Nonpolar molecules do not have charged regions. – Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms. Section 2-2 Properties of Water

14. Hydrogen bonds are responsible for three important properties of water. –high specific heat –cohesion –adhesion Section 2-2 Properties of Water

15. Many compounds dissolve in water. A solution is formed when one substance dissolves in another. –A solution is a homogeneous mixture. –Solvents dissolve other substances. –Solutes dissolve in a solvent. solution Section 2-2 Properties of Water

16. “Like dissolves like.” –Polar solvents dissolve polar solutes. –Nonpolar solvents dissolve nonpolar solutes. –Polar substances and nonpolar substances generally remain separate. Section 2-2 Properties of Water

17. Some compounds form acids or bases. An acid releases a hydrogen ion when it dissolves in water. –high H + concentration –pH less than 7 more acidic stomach acid pH between 1 and 3 Section 2-2 Properties of Water

18. A base removes hydrogen ions from a solution. –low H + concentration –pH greater than 7 bile pH between 8 and 9 more basic Section 2-2 Properties of Water

19. A neutral solution has a pH of 7. pure water pH 7 Section 2-2 Properties of Water

20. Carbon atoms have unique bonding properties. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms. Carbon-based molecules have three general types of structures. –straight chain –branched chain –ring Section 2-3: Carbon-Based Molecules

21. Many carbon-based molecules are made of many small subunits bonded together. –Monomers are the individual subunits. –Polymers are made of many monomers. Section 2-3: Carbon-Based Molecules

22. Four main types of carbon-based molecules are found in living things. Carbohydrates are made of carbon, hydrogen, and oxygen. Section 2-3: Carbon-Based Molecules

23. Four main types of carbon-based molecules are found in living things. Carbohydrates are made of carbon, hydrogen, and oxygen. –Carbohydrates include sugars and starches. –Monosaccharides are simple sugars. –Polysaccharides include starches, cellulose, and glycogen. Section 2-3: Carbon-Based Molecules

24. Carbohydrates can be broken down to provide energy for cells. Some carbohydrates are part of cell structure. Polymer (starch) Starch is a polymer of glucose monomers that often has a branched structure. Polymer (cellulose) Cellulose is a polymer of glucose monomers that has a straight, rigid structure monomer Section 2-3: Carbon-Based Molecules

25. –Many contain carbon chains called fatty acids. –Fats and oils contain fatty acids bonded to glycerol. Lipids are nonpolar molecules that include fats, oils, and cholesterol. Triglyceride Section 2-3: Carbon-Based Molecules

26. Lipids have several different functions. –broken down as a source of energy –make up cell membranes – used to make hormones Section 2-3: Carbon-Based Molecules

27. Fats and oils have different types of fatty acids. –saturated fatty acids –unsaturated fatty acids Section 2-3: Carbon-Based Molecules

28. Phospholipids make up all cell membranes. –Polar phosphate “head” –Nonpolar fatty acid “tails” Phospholipid Section 2-3: Carbon-Based Molecules

29. Proteins are polymers of amino acid monomers. –Twenty different amino acids are used to build proteins in organisms. Section 2-3: Carbon-Based Molecules

30. –Amino acids differ in side groups, or R groups. Proteins are polymers of amino acid monomers. –Twenty different amino acids are used to build proteins in organisms. Section 2-3: Carbon-Based Molecules

31. –Amino acids are linked by peptide bonds. Proteins are polymers of amino acid monomers. –Amino acids differ in side groups, or R groups. –Twenty different amino acids are used to build proteins in organisms. Section 2-3: Carbon-Based Molecules

32. Proteins differ in the number and order of amino acids. –Amino acids interact to give a protein its shape. –Incorrect amino acids change a protein’s structure and function. hydrogen bond Hemoglobin Section 2-3: Carbon-Based Molecules

33. Nucleic acids are polymers of monomers called nucleotides. Section 2-3: Carbon-Based Molecules

34. –Nucleotides are made of a sugar, phosphate group, and a nitrogen base. A phosphate group nitrogen-containing molecule, called a base deoxyribose (sugar) Nucleic acids are polymers of monomers called nucleotides. Section 2-3: Carbon-Based Molecules

35. –DNA stores genetic information. Nucleic acids are polymers of monomers called nucleotides. –Nucleotides are made of a sugar, phosphate group, and a nitrogen base. –RNA builds proteins. DNA RNA Section 2-3: Carbon-Based Molecules

36. Bonds break and form during chemical reactions. Chemical reactions change substances into different ones by breaking and forming chemical bonds. –Reactants are changed during a chemical reaction. –Products are made by a chemical reaction. Section 2-4: Chemical Reactions

37. A reaction is at equilibrium when reactants and products form at the same rate. CO 2 + H 2 O H 2 CO 3 Bond energy is the amount of energy that breaks a bond. –Energy is added to break bonds. –Energy is released when bonds form. Section 2-4: Chemical Reactions

38. Chemical reactions release or absorb energy. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction. Section 2-4: Chemical Reactions

39. Exothermic reactions release more energy than they absorb. –Reactants have higher bond energies than products. –Excess energy is released by the reaction. Section 2-4: Chemical Reactions

40. Endothermic reactions absorb more energy than they release. –Reactants have lower bond energies than products. –Energy is absorbed by the reaction to make up the difference. Section 2-4: Chemical Reactions

41. A catalyst lowers activation energy. Catalysts are substances that speed up chemical reactions. –decrease activation energy & increase reaction rate –Is NOT used up during a reaction and do NOT alter the reaction equilibrium Section 2-5: Enzymes

42. Enzymes allow chemical reactions to occur under tightly controlled conditions. Enzymes are catalysts in living things. –Enzymes are needed for almost all processes. –Most enzymes are proteins. Section 2-5: Enzymes

43. Disruptions in homeostasis can prevent enzymes from functioning. –Enzymes function best in a small range of conditions. –Changes in temperature and pH can break hydrogen bonds. –An enzyme’s function depends on its structure. Section 2-5: Enzymes

44. An enzyme’s structure allows only certain reactants to bind to the enzyme. –substrates –active site substrates (reactants) enzyme Substrates bind to an enzyme at certain places called active sites. Section 2-5: Enzymes

45. The lock-and-key model helps illustrate how enzymes function. –substrates brought together –bonds in substrates weakened Substrates bind to an enzyme at certain places called active sites. The enzyme brings substrates together and weakens their bonds. The catalyzed reaction forms a product that is released from the enzyme. Section 2-5: Enzymes

47. Enzyme Enhancers and Inhibitors Cofactors are small, nonprotein molecules required for proper enzyme catalysis. Section 2-5: Enzymes

48. COMPETITIVE inhibitors are chemicals that resemble an enzyme’s normal substrate and will compete with it for the ACTIVE site. Here, the BROWN dots are substrate. The BLUE dots are competitive inhibitors. What has happened? Section 2-5: Enzymes

50. NONCOMPETITIVE inhibitors do NOT enter the enzyme’s ACTIVE site, but they will bind to another part of an enzyme molecule and cause it to change shapes so that the substrate can no longer bind. Section 2-5: Enzymes

51. Effects of Temperature and pH on Enzymes High temperatures allows for the maximum number of molecular collisions without denaturing the enzyme (breaking it down). Different types of enzymes have optimal temperatures in which they work. For example, human enzymes work best in 35- 40 degrees Celsius. Section 2-5: Enzymes

52. Enzymes also have an optimal pH. The optimal pH for most enzymes is 6-8. But this is not always so! The optimal pH for enzymes within the stomach tends to be 2. Section 2-5: Enzymes