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1 Chapter 2: The Chemical Level of Organization. 2 Introduction to Chemistry Matter is made up of atoms Atoms join together to form chemicals with different.

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Presentation on theme: "1 Chapter 2: The Chemical Level of Organization. 2 Introduction to Chemistry Matter is made up of atoms Atoms join together to form chemicals with different."— Presentation transcript:

1 1 Chapter 2: The Chemical Level of Organization

2 2 Introduction to Chemistry Matter is made up of atoms Atoms join together to form chemicals with different characteristics Chemical characteristics determine physiology at the molecular and cellular level

3 3 Atomic Particles Proton: –positive, 1 mass unit Neutron: –neutral, 1 mass unit Electron: –negative, low mass

4 4 Particles and Mass Atomic number: –number of protons Mass number: –number of protons plus neutrons Atomic weight: –exact mass of all particles (daltons)

5 5 Isotopes 2 or more elements with equal numbers of protons but different numbers of neutrons Electron shell p+p+ p+p+ p + n n n e e e (a)Hydrogen-1 (electron-shell model) (b)Hydrogen-2 deuterium (c)Hydrogen-3, tritium

6 6 Elements in the Human Body Table 2–1

7 7 How do atoms form molecules and compounds?

8 8 Molecules and Compounds Molecules: –atoms joined by strong bonds Compounds: –atoms joined by strong or weak bonds

9 9 Chemical Bonds Ionic bonds: –attraction between cations (+) and anions (-) Covalent bonds: –strong electron bonds –Non polar covalent bonds: equal sharing of electrons –Polar covalent bonds: unequal sharing of electrons Hydrogen bonds: –weak polar bonds

10 10 Ionic Bonds Figure 2–3a Are atoms with positive or negative charge

11 11 Covalent Bond Formed between atoms that share electrons Hydrogen (H 2 ) Oxygen (O 2 ) Carbon Dioxide (CO 2 ) Nitric Oxide (NO) Molecule Electron-Shell Model and Structural Formula H–H O=O N=O O=C=O Free Radicals: Ion or molecule that contain unpaired electrons in the outermost shell. - Extremely Reactive -Typically enter into destructive reactions -Damage/destroy vital compounds

12 12 Hydrogen Bonds Attractive force between polar covalent molecules Weak force that holds molecules together Hydrogen bonds between H 2 O molecules cause surface tension Figure 2–6

13 13 How is it possible for two samples of hydrogen to contain the same number of atoms, yet have different weights? A.One sample has more bonds. B. One sample contains fewer electrons, decreasing weight. C. One sample contains more of hydrogen’s heavier isotope(s). D. One sample includes more protons, increasing weight.

14 14 Both oxygen and neon are gases at room temperature. Oxygen combines readily with other elements, but neon does not. Why? A. Neon has 8 electrons in its valence shell, oxygen has only 6. B. Neon cannot undergo bonding due to its polarity. C. Neon is exergonic. D. Neon’s molecular weight is too low to allow bonding.

15 15 Both oxygen and neon are gases at room temperature. Oxygen combines readily with other elements, but neon does not. Why? A. Neon has 8 electrons in its valence shell, oxygen has only 6. B. Neon cannot undergo bonding due to its polarity. C. Neon is exergonic. D. Neon’s molecular weight is too low to allow bonding.

16 16 Which kind of bond holds atoms in a water molecule together? What attracts water molecules to one another? A. polar covalent bonds; hydrogen bonds B. ionic bonds; charge interactions C. hydrogen bonds; charge interactions D. covalent bonds; hydrogen bonds

17 17 Why are chemical reactions important to physiology?

18 18 Energy Energy: –the capacity to do work Work: –a change in mass or distance

19 19 Forms of Energy Kinetic energy: –energy of motion Potential energy: –stored energy Chemical energy: –potential energy stored in chemical bonds When energy is exchanged, heat is produced - cells cannot capture it or use it for work

20 20 Break Down, Build Up Decomposition reaction (catabolism): AB  A + B Synthesis reaction (anabolism): A + B  AB Exchange reaction (reversible): AB + CD  AD + CB If Water is Involved: Hydrolysis: A—B—C—D—E + H 2 O  A—B—C—H + HO—D—E Dehydration synthesis (condensation): A—B—C—H + HO—D—E  A—B—C—D—E + H 2 O

21 21 KEY CONCEPT Reversible reactions seek equilibrium, balancing opposing reaction rates Add or remove reactants: –reaction rates adjust to reach a new equilibrium

22 22 How do enzymes control metabolism?

23 23 Figure 2–7 Activation Energy Chemical reactions in cells cannot start without help Activation energy gets a reaction started

24 24 Materials in Reactions Reactants: –materials going into a reaction Products: –materials coming out of a reaction Enzymes: –proteins that lower the activation energy of a reaction

25 25 Energy In, Energy Out Exergonic reactions: –produce more energy than they use –Heat will be the by-product Endergonic reactions: –use more energy than they produce Most chemical reactions that sustain life cannot occur unless the right enzymes are present

26 26 In cells, glucose, a six-carbon molecule, is converted into two three- carbon molecules by a reaction that releases energy. How would you classify this reaction? A. endergonic B. exergonic C. decomposition D. B and C

27 27 In cells, glucose, a six-carbon molecule, is converted into two three- carbon molecules by a reaction that releases energy. How would you classify this reaction? A. endergonic B. exergonic C. decomposition D. B and C

28 28 Why are enzymes needed in our cells? A. to promote chemical reactions B. for chemical reactions to proceed under conditions compatible with life C. to lower activation energy requirements D. all of the above

29 29 What is the difference between organic and inorganic compounds?

30 30 Organic and Inorganic Molecules Organic: –molecules based on carbon and hydrogen Inorganic: –molecules not based on carbon and hydrogen

31 31 Essential Molecules Nutrients: –essential molecules obtained from food Metabolites: –molecules made or broken down in the body

32 32 Why is water so important to life?

33 33 Properties of Water Solubility: –water’s ability to dissolve a solute in a solvent to make a solution Reactivity: –most body chemistry uses or occurs in water High heat capacity: –water’s ability to absorb and retain heat Lubrication: –to moisten and reduce friction Water is the key structural and functional component of cells and their control mechanisms, the nucleic acids

34 34 Aqueous Solutions Figure 2–8 Polar water molecules form hydration spheres around ions and small polar molecules to keep them in solution

35 35 Electrolytes Inorganic ions: conduct electricity in solution Electrolyte imbalance seriously disturbs vital body functions

36 36 Molecules and Water Hydrophilic: –hydro = water, philos = loving –reacts with water Hydrophobic: –phobos = fear –does not react with water

37 37 Solutions Suspension: –a solution in which particles settle (sediment) Concentration: –the amount of solute in a solvent (mol/L, mg/mL)

38 38 What is pH and why do we need buffers?

39 39 pH: Neutral, Acid, or Base? pH: –the concentration of hydrogen ions (H + ) in a solution Neutral pH: –a balance of H + and OH — –pure water = 7.0 Acid (acidic): pH lower than 7.0 –high H + concentration, low OH — concentration Base (basic): pH higher than 7.0 –low H + concentration, high OH — concentration

40 40 pH Scale Figure 2–9 Has an inverse relationship with H + concentration: –more H + ions mean lower pH, less H + ions mean higher pH

41 41 KEY CONCEPT pH of body fluids measures free H + ions in solution Excess H + ions (low pH): Acidosis –damages cells and tissues –alters proteins –interferes with normal physiological functions Excess OH — ions (high pH): Alkalosis –Uncontrollable and sustained skeletal muscle contractions

42 42 Controlling pH Salts: –positive or negative ions in solution –contain no H + or OH — (NaCl) Buffers: –weak acid/salt compounds –neutralizes either strong acid or strong base

43 43 Why does a solution of table salt conduct electricity, but a sugar solution does not? A. Electrical conductivity requires ions. B. Sugar forms a colloid, salt forms a suspension. C. Electricity is absorbed by glucose molecules. D. Table salt is hydrophobic, sugar is hydrophilic.

44 44 How does an antacid help decrease stomach discomfort? A.by reducing buffering capacity of the stomach B. by decreasing pH of stomach contents C. by reacting a weak acid with a stronger one D. by neutralizing acid using a weak base

45 45 What kinds of organic compounds are there, and how do they work? Organic Compounds

46 46 Functional Groups of Organic Compounds Table 2–4 Molecular groups which allow molecules to interact with other molecules

47 47 Carbohydrates Consist of C:H:O in 1:2:1 ratio 1. Monosaccharides: –simple sugars with 3 to 7 carbon atoms (glucose) Glucose: important metabolic fuel 2. Disaccharides: –2 simple sugars condensed by dehydration synthesis (sucrose)

48 48 Simple Sugars Figure 2–10 Structural Formula: Straight-chain form Ring from 3-D Isomers: Glucose vs. Fructose: - Same chemical formula but different shape

49 49 Polysaccharides Chains of many simple sugars (glycogen) Formation: –Dehydration synthesis Breakdown: –Hydrolysis synthesis Figure 2–12 Glycogen: made and stored in muscle cells

50 50 Carbohydrate Functions Table 2–5 Polysaccharides Glycogen: made and stored in muscle cells Cellulose: structural component of plants Cattle, sheep, and deer -Ruminant Animals: Cattle, sheep, and deer

51 51 The Ruminant Stomach Ruminant stomach is polygastric: four compartments -Rumen -Reticulum -Abomasum -Omasum

52 52 Rumen  Occupies 80% of the stomach  Muscular Pillar  Contract to mix feed  Digest starch and fibers  Microbes produce VFA’s  Lined with Papillae  pH of  Provide a suitable environment for bacteria and protozoa

53 53 KEY CONCEPT Carbohydrates are quick energy sources and components of membranes Lipids have many functions, including membrane structure and energy storage –Provides 2x more energy then carbohydrates

54 54 Lipids Mainly hydrophobic molecules such as fats, oils, and waxes Made mostly of carbon and hydrogen atoms (1:2), and some oxygen –Less oxygen then carbon

55 55 Classes of Lipids Fatty acids Eicosanoids Glycerides Steroids Phospholipids and glycolipids

56 56 Fatty Acids Carboxyl group -COOH –Hydrophilic Hydrocarbon tail: –Hydrophobic –Longer tail = lower solubility Saturated vs. Unsaturated –Saturated: solid at room temp. Cause solid plaques in arteries –Unsaturated: liquid at room temp. Healthier Figure 2–13

57 57 Eicosanoids Used for cellular communication Never burned for energy 1. Leukotrienes: –active in immune system –Used by cells to signal injury 2. Prostaglandins: local hormones –Used for cell-to-cell signaling to coordinate events

58 58 Figure 2–16 Steroids 4 carbon ring with attached carbon chains Not burned for energy

59 59 Types of Steroids Cholesterol: –cell membrane formation and maintenance, cell division, and osmotic stability Estrogens and testosterone: –Regulation of sexual function Corticosteroids and calcitrol: –Tissue metabolism and mineral balance Bile salts: –Processing of dietary fats

60 60 Figure 2–15 Glycerides Glycerides: are the fatty acids attached to a glycerol molecule Triglyceride: are the 3 fatty-acid tails, fat storage molecule Fat Deposits are Important 1.Energy Storage 2.Insulation 3.Mechanical Protection -Knees and Eye Sockets

61 61 Phospholipids Vs. Glycolipids Combination Lipids Figure 2–17a, b Diglyceride Cell Membranes are Composed of these lipids Hydrophilic Hydrophobic

62 62 Phospholipids Vs. Glycolipids Combination Lipids Figure 2–17c Spontaneous formation of Micelle

63 63 5 Lipid Types Table 2–6

64 64 A food contains organic molecules with the elements C, H, and O in a ratio of 1:2:1. What class of compounds do these molecules belong to, and what are their major functions in the body? A.lipids; energy source B. proteins; support and movement C. nucleic acids; determining inherited characteristics D. carbohydrates; energy source

65 65 When two monosaccharides undergo a dehydration synthesis reaction, which type of molecule is formed? A.polypeptide B. disaccharide C. eichosanoid D. polysaccharide

66 66 Which kind of lipid would be found in a sample of fatty tissue taken from beneath the skin? A.eichosanoid B. steroid C. triglyceride D. phospholipid

67 67 Which lipids would you find in human cell membranes? A.cholesterol B. glycolipids C. phospholipids D. all of the above

68 68 Protein Structure Proteins are the most abundant and important organic molecules Basic elements: –carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) Basic building blocks: –20 amino acids

69 69 Protein Functions 7 major protein functions: –support: structural proteins –movement: contractile proteins –transport: transport proteins –buffering: regulation of pH –metabolic regulation: enzymes –coordination and control: hormones –defense: antibodies

70 70 Proteins Proteins: –control anatomical structure and physiological function –determine cell shape and tissue properties – perform almost all cell functions

71 71 Amino Acid Structure 1.central carbon 2.hydrogen 3.amino group (—NH 2 ) 4.carboxylic acid group (—COOH) 5.variable side chain or R group Figure 2-18

72 72 Peptide Bond A dehydration synthesis between: –amino group of 1 amino acid –and the carboxylic acid group of another amino acid –producing a peptide

73 73 Figure 2–20a Primary Structure Polypeptide: –Linear sequence of amino acids How many amino acids were bound together What order they are bound

74 74 Secondary Structure Figure 2–20b Hydrogen bonds form spirals or pleats

75 75 Figure 2–20c Tertiary Structure Secondary structure folds into a unique shape Global coiling or folding due to R group interaction

76 76 Quaternary Structure Figure 2–20d Final protein shape: –several tertiary structures together Fibrous proteins: - structural sheets Globular proteins: - soluble spheres with active functions

77 77 Shape and Function Protein function is based on shape Shape is based on sequence of amino acids Denaturation: –loss of shape and function due to heat or pH

78 78 Enzymes Enzymes are catalysts: –proteins that lower the activation energy of a chemical reaction –are not changed or used up in the reaction

79 79 How Enzymes Work Figure 2–21 Substrates: reactants in enzymatic reactions Active site: location on an enzyme that fits a particular substrate

80 80 Enzyme Helpers Cofactor: –an ion or molecule that binds to an enzyme before substrates can bind Coenzyme: –nonprotein organic cofactors (vitamins) Isozymes: –2 enzymes that can catalyze the same reaction

81 81 Enzyme Characteristics Specificity: –one enzyme catalyzes one reaction Saturation limits: –an enzyme’s maximum work rate Regulation: –the ability to turn off and on

82 82 Conjugated Protein Glycoproteins: –large protein + small carbohydrate includes enzymes, antibodies, hormones, and mucus production Proteoglycans: –large polysaccharides + polypeptides promote viscosity

83 83 Proteins are chains of which small organic molecules? A.saccharides B. fatty acids C. amino acids D. nucleic acids

84 84 Which level of protein structure would be affected by an agent that breaks hydrogen bonds? A.the primary level of protein structure B. the secondary level of protein structure C. the tertiary level of protein structure D. the protein structure would NOT be affected by this agent

85 85 Why does boiling a protein affect its structural and functional properties? A.Heat denatures the protein, causing unfolding. B. Heat causes the formation of additional quaternary structure. C. Heating rearranges the primary structure of the protein. D. Heat alters the radical groups on the amino acids.

86 86 Why does boiling a protein affect its structural and functional properties? A.Heat denatures the protein, causing unfolding. B. Heat causes the formation of additional quaternary structure. C. Heating rearranges the primary structure of the protein. D. Heat alters the radical groups on the amino acids.

87 87 How might a change in an enzyme’s active site affect its functions? A.increased activity due to a better fit with the substrate B. decreased activity due to a poor substrate fit C. inhibited activity due to no substrate fit D. all of the above

88 88 Nucleic Acids C, H, O, N, and P Large organic molecules, found in the nucleus, which store and process information at the molecular level DNA – deoxyribonucleic acid RNA – ribonucleic acid

89 89 DNA and RNA DNA Determines inherited characteristics Directs protein synthesis Controls enzyme production Controls metabolism RNA Codes intermediate steps in protein synthesis

90 90 KEY CONCEPT DNA in the cell nucleus contains the information needed to construct all of the proteins in the body

91 91 Nucleotides Are the building blocks of DNA Have 3 molecular parts: –sugar (deoxyribose) –phosphate group –nitrogenous base (A, G, T, C)

92 92 The Bases Figure 2–22b, c

93 93 Complementary Bases Purines pair with pyrimidines: DNA: –adenine (A) and thymine (T) –cytosine (C) and guanine (G) RNA: –uracil (U) replaces thymine (T)

94 94 RNA and DNA RNA: –a single strand DNA: –a double helix joined at bases by hydrogen bonds

95 95 Protein Synthesis: Three forms of RNA messenger RNA (mRNA) –Protein blueprint or instructions transfer RNA (tRNA) –Carry amino acids to the place where proteins are being synthesized ribosomal RNA (rRNA) –Forms the site of protein synthesis in the cell Factory = ribosomes

96 96 High-Energy Compounds: ADP and ATP - Assembled using RNA Nucleotides - Bonds are broken easily by cells to release energy as needed -During digestion and cellular respiration: -energy from food is transferred to high energy compounds for quick and easy access.

97 97 ADP to ATP: Phosphorylation ADP vs. ATP: adenosine diphosphate (ADP): –2 phosphate groups (di = 2) adenosine triphosphate (ATP): –3 phosphate groups (tri = 3) Adding a phosphate group to ADP with a high- energy bound to form the high-energy compound ATP ATPase: –the enzyme that catalyzes phophorylation

98 98 Figure 2–24 The Energy Molecule Chemical energy stored in phosphate bonds

99 99 A large organic molecule composed of the sugar ribose, nitrogenous bases, and phosphate groups is which kind of nucleic acid? A.DNA B. ATP C. tRNA D. RNA

100 100 What molecule is produced by the phosphorylation of ADP? A.ATPase B. ATP C. Adenosine Diphosphate D. Uridine Triphosphate

101 101 Compounds Important to Physiology Table 2–8

102 102 SUMMARY Atoms, molecules, and chemical bonds control cellular physiology Metabolism and energy work within the cell Importance of organic and inorganic nutrients and metabolites

103 103 SUMMARY Role of water and solubility in metabolism and cell structure Chemistry of acids and bases, pH and buffers Structure and function of carbohydrates, lipids, proteins, and nucleic acids


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