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UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life

UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of Life I. Atoms, Ions, and Molecules (2.1) . A. Living things consist of atoms of different elements. 1. An atom is the smallest basic unit of matter

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UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life

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  1. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life

  2. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of Life I. Atoms, Ions, and Molecules (2.1) A. Living things consist of atoms of different elements

  3. 1. An atom is the smallest basic unit of matter 2. An element is one type of atom 3. An atom has a nucleus and electrons

  4.  a. The nucleus has protons and neutrons b. Electrons are in energy levels outside the nucleus

  5. 4. A compound is made of atoms of different elements bonded together a. Water (H20) b. Carbon dioxide (CO2) c. Many other carbon-based compounds in living things.

  6. B. Ions form when atoms gain or loseelectrons 1. An ion is an atom that has gained or lost one or more electrons a. Positive ions -lost electron(s) b. Negative ions -gain electron(s) 2. Ionic bonds form between oppositely charged ions

  7. 1. A covalent bond forms when atoms share a pair of electrons a. Multiple covalent bonds b. Diatomic molecules

  8. 2. A molecule is two or more atoms held together by covalent bonds

  9. II. Properties of Water A. Life depends on hydrogen bonds in water 1. Water is a polar molecule a. Polar molecules have slightly charged regions

  10.  b. Nonpolar molecules do not have charged regions

  11. c. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

  12. 2. Hydrogen bonds are responsible for three important properties of water. a. High specific heat b. Cohesion- attraction between molecules of the same substance (because of hydrogen bonds, water is very cohesive)

  13. c. Adhesion- attraction between different substances. Adhesion between water and other charged or polar substances very important force. (responsible for capillary action)

  14. B. Many compounds dissolve in water 1. A solution is formed when one substance dissolves in another a. A solution is a homogeneous mixture

  15.  b. Solvents dissolve other substances c. Solutes dissolve in a solvent

  16. 2. “Like dissolves like” a. Polar solvents dissolvepolar solutes b. Nonpolar solvents dissolvenonpolar solutes c. Polar substances and nonpolar substances generally remain separate

  17. C. Some compounds form acids and bases 1. An acid releases a hydrogen ion when it dissolves in water a. High H+ concentration   b. pHless than 7

  18. 2. A base removes hydrogen ions from a solution a. low H+ concentration   b. pH greater than 7

  19. 3. A neutral solution has a pH of 7

  20. III. Carbon-Based Molecules (2.3) A. Carbon atoms have unique bonding properties 1. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.

  21. 2. Carbon-based molecules have three general types of structures a. Straight chain b. Branched chain c. Ring

  22. B. Many carbon based molecules are made of many small subunits bonded together 1. Monomers are the individual subunits  2. Polymers are made of many monomers

  23. B. Four main types of carbon-based molecules are found in living things. 1. Carbohydrates are made of carbon, hydrogen, and oxygen a. Carbohydrates include sugars and starches b.Monosaccharides are simple sugars

  24. c. Polysaccharides include starches, cellulose, and glycogen d. Carbohydrates can be broken down to provide energy for cells e. Some carbohydrates are part of cell structure

  25. 2. Lipids are nonpolar molecules that include fats, oils, and cholesterol a. Many contain carbon chains called fatty acids b. Fats and oils contain fatty acids bonded to glycerol.

  26. c. Lipids have several different functions 1). Broken down as a source of energy 2). Make up cell membranes 3). Used to make hormones

  27. d. Fats and oils have different types of fatty acids 1). Saturated fatty acids 2). Unsaturated fatty acids

  28. e. Phospholipids make up all cell membranes 1). Polar phosphate “head” 2). Nonpolar fatty acid “tails”

  29. 3. Proteins are polymers of amino acid monomers a. Twenty different amino acids are used to build proteins in organisms

  30.  b. Amino acids differ in side groups, or R groups c. Amino acids are linked by peptide bonds

  31. d. Proteins differ in the number and order of amino acids   1). Amino acids interact to give a protein its shape   2). Incorrect amino acids change a proteins structure and function

  32. 4. Nucleic acids are polymers of monomers called nucleotides a. Nucleotides are made of sugar, phosphate group, and a nitrogen base.

  33. b. DNA storesgenetic information c. RNA buildsproteins

  34. IV. Chemical Reactions (2.4) A. Bondsbreak and form during chemical reactions. 1. Reactants are changed during a chemical reaction 2. Products are made by a chemical reactions. C6H12O6 + O2 CO2 + H2O reactants products

  35. B. Bond energy is the amount of energy that breaks a bond 1. Energy is added To break bonds 2. Energy is released when bonds form

  36. C. A reaction is at equilibrium when reactants and products form at the same rate. CO2 + H2O H2CO3

  37. D. Chemical reactions release or absorb energy 1. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

  38.  2. Exothermic reactions release more energy than they absorb. a. Reactants have higher bond energy than products b. Excess energy is released by the reaction

  39. 3. Endothermic reactions absorb more energy than they release. a. Reactants have lower bond energy than products   a. Energy is absorbed by the reaction to make up the difference.

  40. V. Enzymes (2.5) A. A catalysts lowersactivation energy 1. Catalysts are substances that speed upchemical reactions a. Decreaseactivation energy b. Increasereaction rate

  41. B. Enzymes allow chemical reactions to occur under tightly controlled conditions. 1. Enzymes are catalysts in living things a. Enzymes are needed for almost all processes b. Most enzymes are proteins

  42. C. Disruptions in homeostasis can prevent enzymes from functioning. 1. Enzymes function best in a small range of conditions 2. Changes in temperature and pH can break hydrogen bonds. 3. An enzyme’s function depends on its structure

  43. D. An enzyme’s structure allows only certain reactants to bind to the enzyme 1. Substrates 2. Active Site

  44. E. The lock-and-key model helps illustrate how enzymes function 1. Substrates brought together 2. bonds in substrates weakened

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