Chapter 2 The Chemical Basis of Life

Transcription

1 Chapter 2 The Chemical Basis of Life PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Lecture by Edward J. Zalisko

2 Figure Warmup: page 17

3 Figure Chapter 2 Objectives: You will H O H Describe Elements, Atoms, and Compounds Define Biologically Significant Chemical Bonds Illustrate Water s Life- Supporting Properties

4 ELEMENTS, ATOMS, AND COMPOUNDS

5 Table 2.1

6 Figure Sodium (Na) Chlorine (Cl) Sodium chloride (NaCl)

7 Figure 2.2a An iodine deficiency prevents production of thyroid hormones, resulting in goiter

8 Figure 2.2b Fluoride is usually added to municipal water and dental products to help reduce tooth decay

9 Figure 2.2b Is this GOOD or BAD?

10 Figure 2.2b Science only presents data, it does not give a value (good or bad)

11 Figure 2.2c

12 Figure 2.3 Nucleus 2e Electron cloud Protons Neutrons Nucleus 2 Electrons

13 Table 2.3

14 2.4 CONNECTION: Isotopes Living cells cannot distinguish between isotopes of the same element. Therefore, radioactive isotopes can act as tracers.

15 Figure 2.4a Positron-emission tomography (PET) detects the location of injected radioactive materials

16 Figure 2.4b Healthy person Alzheimer s patient

17 2.4 Uncontrolled exposure can damage living cells, especially DNA. Chemical bonds are broken by the emitted energy, which causes abnormal bonds to form.

18 You should now be able to 1. Describe the importance of chemical elements to living organisms. 2. Explain the formation of compounds. 3. Describe the structure of an atom.

19 CHEMICAL BONDS

20 Figure Chapter 2 Objectives: You will H O H Describe Elements, Atoms, and Compounds Define Biologically Significant Chemical Bonds Illustrate Water s Life- Supporting Properties

21 Figure 2.5a

22 Figure 2.5b-0 First shell Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Second shell Sodium Magnesium Aluminum Silicon Phosphorus Sulfur Chlorine Argon Third shell

23 Figure 2.5b-1 Hydrogen Lithium Beryllium Boron Carbon Sodium Magnesium Aluminum Silicon

24 Figure 2.5b-2 Helium Nitrogen Oxygen Fluorine Neon Phosphorus Sulfur Chlorine Argon

25 Figure 2.UN04 F K Fluorine atom Potassium atom

26 Animation: Covalent Bonds

27 Figure Molecular Formula Electron Distribution Diagram Structural Formula Space-Filling Model H 2 Hydrogen H H Single bond O 2 Oxygen O O Double bond H CH 4 Methane H C H H Nonpolar covalent bonds H 2 O Water H O H Polar covalent bonds (slightly ) Polar covalent bonds in a water molecule H O H (slightly +) (slightly +)

28 Figure Molecular Formula Electron Distribution Diagram Structural Formula Space-Filling Model H 2 Hydrogen H H Single bond O 2 Oxygen O O Double bond

29 Figure Molecular Formula Electron Distribution Diagram Structural Formula Space-Filling Model H CH 4 Methane H C H H Nonpolar covalent bonds H 2 O Water H O H Polar covalent bonds

30 Figure (slightly ) O H H (slightly +) (slightly +) Polar covalent bonds in a water molecule

31 Animation: Water Structure

32 Figure 2.8 ( ) (+) Hydrogen bond (+) ( ) ( ) (+) (+) Polar covalent bonds ( )

33 Figure 2.9 Chemical reactions do not create or destroy matter. only rearrange matter. 2 H 2 + O 2 2 H 2 O Reactants Products

34 Figure 2.7a-1 Na Cl Na Sodium atom Cl Chlorine atom

35 Figure 2.7a-2 + Na Cl Na + Cl Na Sodium atom Cl Chlorine atom Na + Sodium ion Cl Chloride ion Sodium chloride (NaCl)

36 Animation: Ionic Bonds

37 Figure 2.7b-0 Cl Na +

38 You should now be able to 1. Distinguish between ionic, hydrogen, and covalent bonds. 2. Define a chemical reaction and explain how it changes the composition of matter. 3. List and define the life-supporting properties of water. 4. Explain the ph scale and the formation of acid and base solutions Pearson Education, Inc Pearson

39 WATER S LIFE-SUPPORTING PROPERTIES

40 Figure Chapter 2 Objectives: You will H O H Describe Elements, Atoms, and Compounds Define Biologically Significant Chemical Bonds Illustrate Water s Life- Supporting Properties

41 2.10 Water Hydrogen bonds cohesion. adhesion.

42 Animation: Water Transport

43 Figure 2.10 high surface tension

44 2.11 Water s hydrogen bonds moderate temperature Thermal energy is the energy associated with the random movement of atoms and molecules. heat temperature

45 Ice Water Steam

46 Figure 2.11 Evaporative cooling. the molecules with the greatest energy leave the surface

47 Figure Ice Hydrogen bonds are stable. Hydrogen bond Liquid water Hydrogen bonds constantly break and re-form.

48 Figure 2.UN02 Liquid water: Hydrogen bonds constantly break and re-form Ice: Stable hydrogen bonds hold molecules apart

49 2.13 Water is the solvent of life A solution is a liquid consisting of a uniform mixture of two or more substances. solvent. solute.

50 Figure 2.13 Positive hydrogen ends of water molecules attracted to negative chloride ion Negative oxygen ends of water molecules attracted to positive sodium ion Cl Na Na Cl + + Salt crystal

51 Increasingly BASIC (Higher OH concentration) Increasingly ACIDIC (Higher H + concentration) Figure ph scale Battery acid Lemon juice, gastric juice Vinegar, cola Tomato juice H + H + H + OH H + OH H + H + H H + + Acidic solution NEUTRAL [H + ] = [OH ] Rainwater Human urine Saliva Pure water Human blood, tears Seawater H + OH OH H + OH OH OH H + H + H + Neutral solution Milk of magnesia Household ammonia Household bleach Oven cleaner OH OH OH OH H + OH OH OH H + Basic solution

52 Increasingly ACIDIC (Higher H + concentration) Figure ph scale 0 Battery acid 1 NEUTRAL [H + ] = [OH ] Lemon juice, gastric juice Vinegar, cola Tomato juice Rainwater Human urine Saliva Pure water

53 Increasingly BASIC (Higher OH concentration) Figure NEUTRAL [H + ] = [OH ] ph scale 7 8 Pure water Human blood, tears Seawater Milk of magnesia Household ammonia Household bleach Oven cleaner

54 Figure H + H + H + OH OH H + H + H + H + H + Acidic solution H + OH OH H + OH OH OH H + H + H + Neutral solution OH OH OH OH H + OH OH OH H + Basic solution

55 2.15 SCIENTIFIC THINKING: CO 2 on coral reefs About 25% of human-generated CO 2 is absorbed by oceans. CO 2 dissolved in seawater lowers the ph of the ocean in a process known as ocean acidification.

56 2.15 (H + ) combine with carbonate ions (CO 3 2 ) to form bicarbonate ions (HCO 3 ). reduces the carbonate ion concentration available to corals and other shell-building animals.

57 2.15 SCIENTIFIC THINKING: Scientists study the effects of rising atmospheric CO 2 on coral reef ecosystems In a controlled experiment, scientists looked at the effect of decreasing carbonate ion concentration on the rate of calcium deposition by reef organisms. The lower the concentration of carbonate ions, the lower the rate of calcification, and thus the slower the growth of coral animals. The results from experimental and observational field studies of sites where ph naturally varies have dire implications for the health of coral reefs and the diversity of organisms they support.

58 Figure 2.15a Calcification rate (mmol CaCO 3 /m 2 day) [CO 2 3 ] (μmol/kg of seawater) Source: Adaption of figure 5 from Effect of Calcium Carbonate Saturation State on the Calcification Rate of an Experimental Coral Reef by C. Langdon, et al., from Global Biogeochemical Cycles, June 2000, Volume 14(2). Copyright 2000 by American Geophysical Union. Reprinted with permission of Wiley Inc.

59 Figure 2.15b A champagne reef with bubbles of CO 2 rising from a volcanic seep Rising CO 2 bubbles lower the ph of the water

60 Ocean Acidification Video

61 2.16 EVOLUTION CONNECTION: The search for extraterrestrial life centers on the search for water Why?

62 You should now be able to 1. List and define the life-supporting properties of water. 2. Explain the ph scale and the formation of acid and base solutions.

63 Figure 2.UN03-0 Atoms have positively charged have neutral have negatively charged (a) number present equals atomic number of each element (b) (d) number may differ in (c) number in outer shell determines formation of H Chemical Bonds electron transfer between atoms creates electron sharing between atoms creates Na Cl H H ions (e) attraction between ions creates unequal equal sharing creates sharing creates (f) (g) nonpolar covalent bonds H ( ) O H (+) (+) water example is has important qualities due to polarity and can lead to (h) H (+) ( ) O

64 Chapter 2 The Chemical Basis of Life Clicker Questions for Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Updated by Shannon Datwyler

65 Concept Check The reactive properties or chemical behavior of an atom mostly depend on the number of a) the electrons in each electron shell of the atom. b) the neutrons found in the nucleus. c) the filled electron shells. d) the electrons in the outer electron shell of the atom.

66 Answer The reactive properties or chemical behavior of an atom mostly depend on the number of a) the electrons in each electron shell of the atom. b) the neutrons found in the nucleus. c) the filled electron shells. d) the electrons in the outer electron shell of the atom.

67 Concept Check Water molecules form hydrogen bonds because a) the water molecule is polar. b) the oxygen molecule is positively charged. c) the water molecule forms a tetrahedron. d) the hydrogen atoms are negatively charged.

68 Answer Water molecules form hydrogen bonds because a) the water molecule is polar. b) the oxygen molecule is positively charged. c) the water molecule forms a tetrahedron. d) the hydrogen atoms are negatively charged.

69 Interpreting Data This is the general equation for photosynthesis the process of capturing sunlight energy and converting it to chemical energy. Which of the following are the reactants of this reaction? a) C 6 H 12 O 6 and O 2 b) CO 2 and H 2 O

70 Answer This is the general equation for photosynthesis the process of capturing sunlight energy and converting it to chemical energy. Which of the following are the reactants of this reaction? a) C 6 H 12 O 6 and O 2 b) CO 2 and H 2 O

71 Interpreting Data Earth s oceans are immense. Small floating plant-like organisms called phytoplankton contribute to ocean productivity. As ocean productivity (the rate of photosynthesis) goes up, what would you predict would happen to global carbon dioxide levels? a) CO 2 levels should also go up. b) CO 2 levels should go down. c) CO 2 levels should remain constant.

72 Answer Earth s oceans are immense. Small floating plant-like organisms called phytoplankton contribute to ocean productivity. As ocean productivity (the rate of photosynthesis) goes up, what would you predict would happen to global carbon dioxide levels? a) CO 2 levels should also go up. b) CO 2 levels should go down. c) CO 2 levels should remain constant.

73 Concept Check What will happen as CO 2 levels in the oceans increase? a) The ocean will become more basic b) The ocean will become more acidic c) Growth rates of organisms such as corals will decrease d) Both a and b e) Both b and c

74 Answer What will happen as CO 2 levels in the oceans increase? The ocean will become more acidic e) Both b and c rowth rates of organisms such as corals will decrease a) Both a and b

75 Biology and Society One of the authors of your text once overheard the following: It s paranoid and ignorant to worry about industry or agriculture contaminating the environment with their chemical wastes. After all, this stuff is just made of the same atoms that were already present in our environment anyway. What do you think of this statement? Strongly A B C D E Strongly Disagree Agree

76 Biology and Society Too little iodine in the diet can lead to goiter the condition afflicting this person. Goiter is not common in developing countries because iodine is added to salt and other foods. Do you think that adding trace elements to food items is a good public policy? Strongly A B C D E Strongly Disagree Agree