1. The Chemistry of Life Chapter 2 Mr. Scott

2. 2-1 Atoms, Ions, and Molecules Living things consist of atoms of different elements. Living things consist of atoms of different elements. An atom is the smallest basic unit of matter. An atom is the smallest basic unit of matter. An element is one type of atom. An element is one type of atom. Can not be broken down into simpler substance Can not be broken down into simpler substance H O

3. 2-1 Atoms, Ions, and Molecules Atomic composition Atomic composition The nucleus has protons and neutrons. Protons (+) Neutrons (no charge) Electrons are in energy levels outside nucleus. Electrons (-) Protons = what an atom is Electrons = what an atom does

4. 2-1 Atoms, Ions, and Molecules Electrons and energy levels Electrons and energy levels 2n 2 – determines number of electrons for energy level 2n 2 – determines number of electrons for energy level n = energy level n = energy level Rule of 8 or octet rule Rule of 8 or octet rule Important for bonding Important for bonding

5. 2-1 Atoms, Ions, and Molecules A compound is made of atoms of different elements bonded together. A compound is made of atoms of different elements bonded together. water (H 2 O) water (H 2 O) Salt (NaCl) Salt (NaCl) O HH _ ++

6. 2-1 Atoms, Ions, and Molecules Ions form when atoms gain or lose electrons. Ions form when atoms gain or lose electrons. An ion is an atom that has gained or lost one or more electrons. An ion is an atom that has gained or lost one or more electrons. positive ions positive ions negative ions negative ions Ionic bonds form between oppositely charged ions. Ionic bonds form between oppositely charged ions. Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) ionic bond gained electron

7. 2-1 Atoms, Ions, and Molecules Atoms share pairs of electrons in covalent bonds. Atoms share pairs of electrons in covalent bonds. A covalent bond forms when atoms share a pair of electrons. A covalent bond forms when atoms share a pair of electrons. Multiple covalent bonds Multiple covalent bonds Diatomic molecules Diatomic molecules Oxygen atom (O)Carbon atom (C)Oxygen atom (O)

8. 2-2 Properties of Water Life depends on hydrogen bonds in water. Life depends on hydrogen bonds in water. Water is a polar molecule. Water is a polar molecule. Polar molecules have slightly charged regions. Polar molecules have slightly charged regions. Nonpolar molecules do not have charged regions. Nonpolar molecules do not have charged regions. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms. O HH _ ++

9. 2-2 Properties of Water Polarity is created by the pull of electrons away from hydrogen towards oxygen Polarity is created by the pull of electrons away from hydrogen towards oxygen This creates partial positive and partial negative regions of the molecule This creates partial positive and partial negative regions of the molecule

10. 2-2 Properties of Water Hydrogen bonds are responsible for three important properties of water. Hydrogen bonds are responsible for three important properties of water. High specific heat Cohesion Adhesion

11. 2-2 Properties of Water High Specific Heat High Specific Heat Water resists changes temperature so must absorb more to change temperature Water resists changes temperature so must absorb more to change temperature Important to cells Important to cells Cohesion Cohesion Attraction between like molecules Attraction between like molecules Produces surface tension Produces surface tension Adhesion Adhesion Attraction between different molecules Attraction between different molecules Important in transport of water in plants Important in transport of water in plants

12. 2-2 Properties of Water Many compounds dissolve in water. Many compounds dissolve in water. A solution is formed when one substance dissolves in another. A solution is formed when one substance dissolves in another. A solution is a homogeneous mixture. A solution is a homogeneous mixture. Solvents dissolve other substances. Solvents dissolve other substances. Solutes dissolve in a solvent. Solutes dissolve in a solvent. solution

13. 2-2 Properties of Water “Like dissolves like.” “Like dissolves like.” Polar solvents dissolve polar solutes. Polar solvents dissolve polar solutes. Water, blood, plasma, sugars, proteins Water, blood, plasma, sugars, proteins Nonpolar solvents dissolve nonpolar solutes. Nonpolar solvents dissolve nonpolar solutes. Oils, fats Oils, fats Polar substances and nonpolar substances generally remain separate. Polar substances and nonpolar substances generally remain separate. Suspension Suspension

14. 2-2 Properties of Water Some compounds form acids or bases. Some compounds form acids or bases. Break into ions An acid releases a hydrogen ion when it dissolves in water. An acid releases a hydrogen ion when it dissolves in water. High H + concentration pH less than 7

15. 2-2 Properties of Water A base removes hydrogen ions from a solution. A base removes hydrogen ions from a solution. Low H+ concentration Low H+ concentration More OH ions present More OH ions present pH greater than 7 pH greater than 7 bile pH between 8 and 9 more basic

16. 2-2 Properties of Water pH and Living Organisms pH and Living Organisms Most need to keep their pH in a small range Most need to keep their pH in a small range Usually around 7 Usually around 7 Some plants thrive in acidic conditions Some plants thrive in acidic conditions Evergreens, azaleas Evergreens, azaleas pH can be regulated by buffers pH can be regulated by buffers Can either bind to H+ to raise pH or release them to lower pH Can either bind to H+ to raise pH or release them to lower pH

17. 2-3 Carbon-Based Molecules Carbon atoms have unique bonding properties. Carbon atoms have unique bonding properties. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms. Carbon-based molecules have three general types of structures. Carbon-based molecules have three general types of structures. straight chain straight chain branched chain branched chain ring ring

18. 2-3 Carbon-Based Molecules Many carbon-based molecules are made of many small subunits bonded together. Many carbon-based molecules are made of many small subunits bonded together. Monomers are the individual subunits. Monomers are the individual subunits. Polymers are made of many monomers. Polymers are made of many monomers.

19. 2-3 Carbon-Based Molecules Four main types of carbon-based molecules are found in living things. Four main types of carbon-based molecules are found in living things. Carbohydrates Carbohydrates Lipids Lipids Proteins Proteins Nucleic Acids Nucleic Acids

20. 2-3 Carbon-Based Molecules Carbohydrates are made of carbon, hydrogen, and oxygen. Carbohydrates are made of carbon, hydrogen, and oxygen. Carbohydrates include sugars and starches. Monosaccharides are simple sugars. Polysaccharides include starches, cellulose, and glycogen.

21. 2-3 Carbon-Based Molecules Carbohydrates can be broken down to provide energy for cells. Carbohydrates can be broken down to provide energy for cells. Some carbohydrates are part of cell structure. 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

22. 2-3 Carbon-Based Molecules Lipids are nonpolar molecules that include fats, oils, and cholesterol. Lipids are nonpolar molecules that include fats, oils, and cholesterol. Many contain carbon chains called fatty acids. Many contain carbon chains called fatty acids. Fats and oils contain fatty acids bonded to glycerol. Fats and oils contain fatty acids bonded to glycerol.

23. 2-3 Carbon-Based Molecules Lipids have several different functions. Lipids have several different functions. Broken down as a source of energy Broken down as a source of energy Make up cell membranes Make up cell membranes Used to make hormones Used to make hormones

24. 2-3 Carbon-Based Molecules Phospholipids make up all cell membranes. Phospholipids make up all cell membranes. Polar phosphate “head” Polar phosphate “head” Nonpolar fatty acid “tails” Nonpolar fatty acid “tails” Phospholipid

25. 2-3 Carbon-Based Molecules Fats and oils have different types of fatty acids. Fats and oils have different types of fatty acids. saturated fatty acids unsaturated fatty acids

26. 2-3 Carbon-Based Molecules Cholesterol Cholesterol Ring structured lipid Ring structured lipid Found in eggs and other fatty foods Found in eggs and other fatty foods Used to make cell membranes and hormones Used to make cell membranes and hormones

27. 2-3 Carbon-Based Molecules Proteins are polymers of amino acid monomers. Proteins are polymers of amino acid monomers. Twenty different amino acids are used to build proteins in organisms. Twenty different amino acids are used to build proteins in organisms. Amino acids differ in side groups, or R groups. Amino acids differ in side groups, or R groups. Amino acids are linked by peptide bonds Amino acids are linked by peptide bonds

28. 2-3 Carbon-Based Molecules Protein structure Protein structure Side groups determine structure Sulfur in the side group causes the protein to bend Hydrogen bonds can form between side groups Causes the protein to fold

29. 2-3 Carbon-Based Molecules Nucleic acids are polymers of monomers called nucleotides. Nucleic acids are polymers of monomers called nucleotides. Nucleotides are made of a sugar, phosphate group, and a nitrogen base. A phosphate group nitrogen-containing molecule, called a base deoxyribose (sugar)

30. 2-4 Chemical Reactions Bonds break and form during chemical reactions. Bonds break and form during chemical reactions. Chemical reactions change substances into different ones by breaking and forming chemical bonds. Chemical reactions change substances into different ones by breaking and forming chemical bonds. Reactants are changed during a chemical reaction. Reactants are changed during a chemical reaction. Products are made by a chemical reaction. Products are made by a chemical reaction.

31. 2-4 Chemical Reactions Bond energy is the amount of energy that breaks a bond. Bond energy is the amount of energy that breaks a bond. Energy is added to break bonds. Energy is added to break bonds. Energy is released when bonds form. Energy is released when bonds form. ● A reaction is at equilibrium when reactants and products form at the same rate. CO 2 + H 2 O ↔H 2 CO 3

32. 2-4 Chemical Reactions Chemical reactions release or absorb energy. Chemical reactions release or absorb energy. Energy added during reactions breaks bonds Energy added during reactions breaks bonds When bonds form, energy is released When bonds form, energy is released During all chemical reactions energy is absorbed and released During all chemical reactions energy is absorbed and released Some release more than absorb and visce versa Some release more than absorb and visce versa

33. 2-4 Chemical Reactions Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

34. 2-4 Chemical Reactions Exothermic reactions release more energy than they absorb. Exothermic reactions release more energy than they absorb. Reactants have higher bond energies than products. Reactants have higher bond energies than products. Excess energy is released by the reaction. Excess energy is released by the reaction.

35. 2-4 Chemical Reactions Endothermic reactions absorb more energy than they release. 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.

36. 2-5 Enzymes A catalyst lowers activation energy. A catalyst lowers activation energy. Catalysts are substances that speed up chemical reactions. Catalysts are substances that speed up chemical reactions. Decrease activation energy Decrease activation energy Increase reaction rate Increase reaction rate

37. 2-5 Enzymes Enzymes allow chemical reactions to occur under tightly controlled conditions. Enzymes allow chemical reactions to occur under tightly controlled conditions. Enzymes are catalysts in living things. Enzymes are catalysts in living things. Enzymes are needed for almost all processes. Enzymes are needed for almost all processes. Most enzymes are proteins. Most enzymes are proteins.

38. 2-5 Enzymes Disruptions in homeostasis can prevent enzymes from functioning. Disruptions in homeostasis can prevent enzymes from functioning. Enzymes function best in a small range of conditions. Enzymes function best in a small range of conditions. Changes in temperature and pH can break hydrogen bonds. Changes in temperature and pH can break hydrogen bonds. An enzyme’s function depends on its structure. An enzyme’s function depends on its structure.

39. 2-5 Enzymes An enzyme’s structure allows only certain reactants to bind to the enzyme. An enzyme’s structure allows only certain reactants to bind to the enzyme. substrates substrates active site active site substrates (reactants) enzyme Substrates bind to an enzyme at certain places called active sites.

40. 2-5 Enzymes The lock-and-key model helps illustrate how enzymes function. The lock-and-key model helps illustrate how enzymes function. Substrates brought together Substrates brought together Bonds in substrates weakened 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.