Chemistry Comes Alive: Part A

Transcription

1 PowerPoint Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R 2 Chemistry Comes Alive: Part A

2 Matter Anything that has mass and occupies space States of matter: 1. Solid definite shape and volume 2. Liquid definite volume, changeable shape 3. Gas changeable shape and volume

3 Energy Capacity to do work or put matter into motion Types of energy: Kinetic energy in action Potential stored (inactive) energy PLAY Animation: Energy Concepts

4 Forms of Energy Chemical energy stored in bonds of chemical substances Electrical energy results from movement of charged particles Mechanical energy directly involved in moving matter Radiant or electromagnetic energy exhibits wavelike properties (i.e., visible light, ultraviolet light, and X-rays)

5 Energy Form Conversions Energy may be converted from one form to another Conversion is inefficient because some energy is lost as heat

6 Composition of Matter Elements Cannot be broken down by ordinary chemical means Each has unique properties: Physical properties Are detectable with our senses, or are measurable Chemical properties How atoms interact (bond) with one another

7 Composition of Matter Atoms Unique building blocks for each element Atomic symbol: one- or two-letter chemical shorthand for each element

8 Major Elements of the Human Body Oxygen (O) Carbon (C) Hydrogen (H) About 96% of body mass Nitrogen (N)

9 Lesser Elements of the Human Body About 3.9% of body mass: Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)

10 Trace Elements of the Human Body < 0.01% of body mass: Part of enzymes, e.g., chromium (Cr), manganese (Mn), and zinc (Zn)

11 Atomic Structure Determined by numbers of subatomic particles Nucleus consists of neutrons and protons

12 Atomic Structure Neutrons No charge Mass = 1 atomic mass unit (amu) Protons Positive charge Mass = 1 amu

13 Atomic Structure Electrons Orbit nucleus Equal in number to protons in atom Negative charge 1/2000 the mass of a proton (0 amu)

14 Models of the Atom Orbital model: current model used by chemists Depicts probable regions of greatest electron density (an electron cloud) Useful for predicting chemical behavior of atoms

15 Models of the Atom Planetary model oversimplified, outdated model Incorrectly depicts fixed circular electron paths Useful for illustrations (as in the text)

16 Nucleus Nucleus Helium atom 2 protons (p + ) 2 neutrons (n 0 ) 2 electrons (e ) (a) Planetary model Helium atom 2 protons (p + ) 2 neutrons (n 0 ) 2 electrons (e ) (b) Orbital model Proton Neutron Electron Electron cloud Figure 2.1

17 Identifying Elements Atoms of different elements contain different numbers of subatomic particles Compare hydrogen, helium and lithium (next slide)

18 Proton Neutron Electron Hydrogen (H) (1p + ; 0n 0 ; 1e ) Helium (He) (2p + ; 2n 0 ; 2e ) Lithium (Li) (3p + ; 4n 0 ; 3e ) Figure 2.2

19 Identifying Elements Atomic number = number of protons in nucleus

20 Identifying Elements Mass number = mass of the protons and neutrons Mass numbers of atoms of an element are not all identical Isotopes are structural variations of elements that differ in the number of neutrons they contain

21 Identifying Elements Atomic weight = average of mass numbers of all isotopes

22 Proton Neutron Electron Hydrogen ( 1 H) (1p + ; 0n 0 ; 1e ) Deuterium ( 2 H) (1p + ; 1n 0 ; 1e ) Tritium ( 3 H) (1p + ; 2n 0 ; 1e ) Figure 2.3

23 Radioisotopes Spontaneous decay (radioactivity) Similar chemistry to stable isotopes Can be detected with scanners

24 Radioisotopes Valuable tools for biological research and medicine Cause damage to living tissue: Useful against localized cancers Radon from uranium decay causes lung cancer

25 Molecules and Compounds Most atoms combine chemically with other atoms to form molecules and compounds Molecule two or more atoms bonded together (e.g., H 2 or C 6 H 12 O 6 ) Compound two or more different kinds of atoms bonded together (e.g., C 6 H 12 O 6 )

26 Mixtures Most matter exists as mixtures Two or more components physically intermixed Three types of mixtures Solutions Colloids Suspensions

27 Solutions Homogeneous mixtures Usually transparent, e.g., atmospheric air or seawater Solvent Present in greatest amount, usually a liquid Solute(s) Present in smaller amounts

28 Concentration of Solutions Expressed as Percent, or parts per 100 parts Milligrams per deciliter (mg/dl) Molarity, or moles per liter (M) 1 mole = the atomic weight of an element or molecular weight (sum of atomic weights) of a compound in grams 1 mole of any substance contains molecules (Avogadro s number)

29 Colloids and Suspensions Colloids (emulsions) Heterogeneous translucent mixtures, e.g., cytosol Large solute particles that do not settle out Undergo sol-gel transformations Suspensions: Heterogeneous mixtures, e.g., blood Large visible solutes tend to settle out

30 Solution Solute particles are very tiny, do not settle out or scatter light. Colloid Solute particles are larger than in a solution and scatter light; do not settle out. Suspension Solute particles are very large, settle out, and may scatter light. Solute particles Solute particles Solute particles Example Mineral water Example Gelatin Example Blood Figure 2.4

31 Mixtures vs. Compounds Mixtures No chemical bonding between components Can be separated physically, such as by straining or filtering Heterogeneous or homogeneous Compounds Can be separated only by breaking bonds All are homogeneous

32 Chemical Bonds Electrons occupy up to seven electron shells (energy levels) around nucleus Octet rule: Except for the first shell which is full with two electrons, atoms interact in a manner to have eight electrons in their outermost energy level (valence shell)

33 Chemically Inert Elements Stable and unreactive Outermost energy level fully occupied or contains eight electrons

34 (a) Chemically inert elements Outermost energy level (valence shell) complete 2e 8e 2e Helium (He) (2p + ; 2n 0 ; 2e ) Neon (Ne) (10p + ; 10n 0 ; 10e ) Figure 2.5a

35 Chemically Reactive Elements Outermost energy level not fully occupied by electrons Tend to gain, lose, or share electrons (form bonds) with other atoms to achieve stability

36 (b) Chemically reactive elements Outermost energy level (valence shell) incomplete 1e 2e 4e Hydrogen (H) (1p + ; 0n 0 ; 1e ) Carbon (C) (6p + ; 6n 0 ; 6e ) 2e 6e 2e 8e1e Oxygen (O) (8p + ; 8n 0 ; 8e ) Sodium (Na) (11p + ; 12n 0 ; 11e ) Figure 2.5b

37 Types of Chemical Bonds Ionic Covalent Hydrogen

38 Ionic Bonds Ions are formed by transfer of valence shell electrons between atoms Anions ( charge) have gained one or more electrons Cations (+ charge) have lost one or more electrons Attraction of opposite charges results in an ionic bond

39 + Sodium atom (Na) (11p + ; 12n 0 ; 11e ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e ) (a) Sodium gains stability by losing one electron, and chlorine becomes stable by gaining one electron. Sodium ion (Na + ) Chloride ion (Cl ) Sodium chloride (NaCl) (b) After electron transfer, the oppositely charged ions formed attract each other. Figure 2.6a-b

40 Formation of an Ionic Bond Ionic compounds form crystals instead of individual molecules NaCl (sodium chloride)

41 CI Na + (c) Large numbers of Na + and Cl ions associate to form salt (NaCl) crystals. Figure 2.6c

42 Covalent Bonds Formed by sharing of two or more valence shell electrons Allows each atom to fill its valence shell at least part of the time

43 Reacting atoms Resulting molecules + or Hydrogen atoms Carbon atom Molecule of methane gas (CH 4 ) (a) Formation of four single covalent bonds: carbon shares four electron pairs with four hydrogen atoms. Structural formula shows single bonds. Figure 2.7a

44 Reacting atoms Resulting molecules Oxygen atom + Oxygen atom Molecule of oxygen gas (O 2 ) (b) Formation of a double covalent bond: Two oxygen atoms share two electron pairs. or Structural formula shows double bond. Figure 2.7b

45 Reacting atoms Resulting molecules Nitrogen atom + or Nitrogen atom Molecule of nitrogen gas (N 2 ) (c) Formation of a triple covalent bond: Two nitrogen atoms share three electron pairs. Structural formula shows triple bond. Figure 2.7c

46 Covalent Bonds Sharing of electrons may be equal or unequal Equal sharing produces electrically balanced nonpolar molecules CO 2

47 Figure 2.8a

48 Covalent Bonds Unequal sharing by atoms with different electron-attracting abilities produces polar molecules H 2 O Atoms with six or seven valence shell electrons are electronegative, e.g., oxygen Atoms with one or two valence shell electrons are electropositive, e.g., sodium

49 Figure 2.8b

50 Figure 2.9

51 Hydrogen Bonds Attractive force between electropositive hydrogen of one molecule and an electronegative atom of another molecule Common between dipoles such as water Also act as intramolecular bonds, holding a large molecule in a three-dimensional shape PLAY Animation: Hydrogen Bonds

52 δ + δ Hydrogen bond (indicated by dotted line) δ + δ δ δ δ + δ + δ + δ + δ (a) The slightly positive ends (δ + ) of the water molecules become aligned with the slightly negative ends (δ ) of other water molecules. Figure 2.10a

53 (b) A water strider can walk on a pond because of the high surface tension of water, a result of the combined strength of its hydrogen bonds. Figure 2.10b

54 Chemical Reactions Occur when chemical bonds are formed, rearranged, or broken Represented as chemical equations Chemical equations contain: Molecular formula for each reactant and product Relative amounts of reactants and products, which should balance

55 Examples of Chemical Equations H + H H 2 (hydrogen gas) (reactants) (product) 4H + C CH 4 (methane)

56 Patterns of Chemical Reactions Synthesis (combination) reactions Decomposition reactions Exchange reactions

57 Synthesis Reactions A + B AB Always involve bond formation Anabolic

58 (a) Synthesis reactions Smaller particles are bonded together to form larger, more complex molecules. Example Amino acids are joined together to form a protein molecule. Amino acid molecules Protein molecule Figure 2.11a

59 Decomposition Reactions AB A + B Reverse synthesis reactions Involve breaking of bonds Catabolic

60 (b) Decomposition reactions Bonds are broken in larger molecules, resulting in smaller, less complex molecules. Example Glycogen is broken down to release glucose units. Glycogen Glucose molecules Figure 2.11b

61 Exchange Reactions AB + C AC + B Also called displacement reactions Bonds are both made and broken

62 (c) Exchange reactions Bonds are both made and broken (also called displacement reactions). Example ATP transfers its terminal phosphate group to glucose to form glucose-phosphate. + Glucose Adenosine triphosphate (ATP) + Glucose phosphate Adenosine diphosphate (ADP) Figure 2.11c

63 Oxidation-Reduction (Redox) Reactions Decomposition reactions: Reactions in which fuel is broken down for energy Also called exchange reactions because electrons are exchanged or shared differently Electron donors lose electrons and are oxidized Electron acceptors receive electrons and become reduced

64 Chemical Reactions All chemical reactions are either exergonic or endergonic Exergonic reactions release energy Catabolic reactions Endergonic reactions products contain more potential energy than did reactants Anabolic reactions

65 Chemical Reactions All chemical reactions are theoretically reversible A + B AB AB A + B Chemical equilibrium occurs if neither a forward nor reverse reaction is dominant Many biological reactions are essentially irreversible due to Energy requirements Removal of products

66 Rate of Chemical Reactions Rate of reaction is influenced by: temperature rate particle size rate concentration of reactant rate Catalysts: rate without being chemically changed Enzymes are biological catalysts

67 PowerPoint Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R 2 Chemistry Comes Alive: Part B

68 Classes of Compounds Inorganic compounds Water, salts, and many acids and bases Do not contain carbon Organic compounds Carbohydrates, fats, proteins, and nucleic acids Contain carbon, usually large, and are covalently bonded

69 Water 60% 80% of the volume of living cells Most important inorganic compound in living organisms because of its properties

70 Properties of Water High heat capacity Absorbs and releases heat with little temperature change Prevents sudden changes in temperature High heat of vaporization Evaporation requires large amounts of heat Useful cooling mechanism

71 Properties of Water Polar solvent properties Dissolves and dissociates ionic substances Forms hydration layers around large charged molecules, e.g., proteins (colloid formation) Body s major transport medium

72 δ δ+ δ + Water molecule Salt crystal Ions in solution Figure 2.12

73 Properties of Water Reactivity A necessary part of hydrolysis and dehydration synthesis reactions Cushioning Protects certain organs from physical trauma, e.g., cerebrospinal fluid

74 Salts Ionic compounds that dissociate in water Contain cations other than H + and anions other than OH Ions (electrolytes) conduct electrical currents in solution Ions play specialized roles in body functions (e.g., sodium, potassium, calcium, and iron)

75 Acids and Bases Both are electrolytes Acids are proton (hydrogen ion) donors (release H + in solution) HCl H + + Cl

76 Acids and Bases Bases are proton acceptors (take up H + from solution) NaOH Na + + OH OH accepts an available proton (H+) OH + H + H 2 O Bicarbonate ion (HCO 3 ) and ammonia (NH 3 ) are important bases in the body

77 Acid-Base Concentration Acid solutions contain [H + ] As [H + ] increases, acidity increases Alkaline solutions contain bases (e.g., OH ) As [H + ] decreases (or as [OH ] increases), alkalinity increases

78 ph: Acid-Base Concentration ph = the negative logarithm of [H + ] in moles per liter Neutral solutions: Pure water is ph neutral (contains equal numbers of H + and OH ) ph of pure water = ph 7: [H + ] = 10 7 M All neutral solutions are ph 7

79 ph: Acid-Base Concentration Acidic solutions [H + ], ph Acidic ph: ph scale is logarithmic: a ph 5 solution has 10 times more H + than a ph 6 solution Alkaline solutions [H + ], ph Alkaline (basic) ph:

80 Concentration (moles/liter) [OH ] [H + ] ph Examples 1M Sodium hydroxide (ph=14) Oven cleaner, lye (ph=13.5) Household ammonia (ph= ) Household bleach (ph=9.5) Egg white (ph=8) Neutral Blood (ph=7.4) Milk (ph= ) Black coffee (ph=5) Wine (ph= ) Lemon juice; gastric juice (ph=2) M Hydrochloric acid (ph=0) Figure 2.13

81 Acid-Base Homeostasis ph change interferes with cell function and may damage living tissue Slight change in ph can be fatal ph is regulated by kidneys, lungs, and buffers

82 Buffers Mixture of compounds that resist ph changes Convert strong (completely dissociated) acids or bases into weak (slightly dissociated) ones Carbonic acid-bicarbonate system

83 Organic Compounds Contain carbon (except CO 2 and CO, which are inorganic) Unique to living systems Include carbohydrates, lipids, proteins, and nucleic acids

84 Organic Compounds Many are polymers chains of similar units (monomers or building blocks) Synthesized by dehydration synthesis Broken down by hydrolysis reactions

85 (a) Dehydration synthesis Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. + Monomer 1 Monomer 2 Monomers linked by covalent bond (b) Hydrolysis Monomers are released by the addition of a water molecule, adding OH to one monomer and H to the other. + Monomer 1 Monomer 2 Monomers linked by covalent bond (c) Example reactions Dehydration synthesis of sucrose and its breakdown by hydrolysis + Water is released Glucose Fructose Water is consumed Sucrose Figure 2.14

86 Carbohydrates Sugars and starches Contain C, H, and O [(CH 2 0) n ] Three classes Monosaccharides Disaccharides Polysaccharides

87 Carbohydrates Functions Major source of cellular fuel (e.g., glucose) Structural molecules (e.g., ribose sugar in RNA)

88 Monosaccharides Simple sugars containing three to seven C atoms (CH 2 0) n

89 Example Hexose sugars (the hexoses shown here are isomers) (a) Monosaccharides Monomers of carbohydrates Example Pentose sugars Glucose Fructose Galactose Deoxyribose Ribose Figure 2.15a

90 Disaccharides Double sugars Too large to pass through cell membranes

91 (b) Disaccharides Consist of two linked monosaccharides Example Sucrose, maltose, and lactose (these disaccharides are isomers) Glucose Fructose Glucose Glucose Galactose Glucose Sucrose Maltose Lactose PLAY Animation: Disaccharides Figure 2.15b

92 Polysaccharides Polymers of simple sugars, e.g., starch and glycogen Not very soluble

93 (c) Polysaccharides Long branching chains (polymers) of linked monosaccharides Example This polysaccharide is a simplified representation of glycogen, a polysaccharide formed from glucose units. Glycogen PLAY Animation: Polysaccharides Figure 2.15c

94 Lipids Contain C, H, O (less than in carbohydrates), and sometimes P Insoluble in water Main types: Neutral fats or triglycerides Phospholipids Steroids Eicosanoids PLAY Animation: Fats

95 Triglycerides Neutral fats solid fats and liquid oils Composed of three fatty acids bonded to a glycerol molecule Main functions Energy storage Insulation Protection

96 (a) Triglyceride formation Three fatty acid chains are bound to glycerol by dehydration synthesis + Glycerol 3 fatty acid chains Triglyceride, or neutral fat 3 water molecules Figure 2.16a

97 Saturation of Fatty Acids Saturated fatty acids Single bonds between C atoms; maximum number of H Solid animal fats, e.g., butter Unsaturated fatty acids One or more double bonds between C atoms Reduced number of H atoms Plant oils, e.g., olive oil

98 Phospholipids Modified triglycerides: Glycerol + two fatty acids and a phosphorus (P)-containing group Head and tail regions have different properties Important in cell membrane structure

99 (b) Typical structure of a phospholipid molecule Two fatty acid chains and a phosphorus-containing group are attached to the glycerol backbone. Example Phosphatidylcholine Polar head Phosphoruscontaining group (polar head ) Glycerol backbone 2 fatty acid chains (nonpolar tail ) Nonpolar tail (schematic phospholipid) Figure 2.16b

100 Steroids Steroids interlocking four-ring structure Cholesterol, vitamin D, steroid hormones, and bile salts

101 (c) Simplified structure of a steroid Four interlocking hydrocarbon rings form a steroid. Example Cholesterol (cholesterol is the basis for all steroids formed in the body) Figure 2.16c

102 Eicosanoids Many different ones Derived from a fatty acid (arachidonic acid) in cell membranes Prostaglandins

103 Other Lipids in the Body Other fat-soluble vitamins Vitamins A, E, and K Lipoproteins Transport fats in the blood

104 Proteins Polymers of amino acids (20 types) Joined by peptide bonds Contain C, H, O, N, and sometimes S and P

105 Amine group Acid group (a) Generalized structure of all amino acids. (b) Glycine is the simplest amino acid. (c) Aspartic acid (an acidic amino acid) has an acid group ( COOH) in the R group. (d) Lysine (a basic amino acid) has an amine group ( NH 2 ) in the R group. (e) Cysteine (a basic amino acid) has a sulfhydryl ( SH) group in the R group, which suggests that this amino acid is likely to participate in intramolecular bonding. Figure 2.17

106 Dehydration synthesis: The acid group of one amino acid is bonded to the amine group of the next, with loss of a water molecule. Peptide bond + Amino acid Amino acid Dipeptide Hydrolysis: Peptide bonds linking amino acids together are broken when water is added to the bond. Figure 2.18

107 Structural Levels of Proteins PLAY Animation: Introduction to Protein Structure

108 Amino acid Amino acid Amino acid Amino acid Amino acid (a) Primary structure: The sequence of amino acids forms the polypeptide chain. PLAY Animation: Primary Structure Figure 2.19a

109 α-helix: The primary chain is coiled to form a spiral structure, which is stabilized by hydrogen bonds. β-sheet: The primary chain zig-zags back and forth forming a pleated sheet. Adjacent strands are held together by hydrogen bonds. (b) Secondary structure: The primary chain forms spirals (α-helices) and sheets (β-sheets). PLAY Animation: Secondary Structure Figure 2.19b

110 Tertiary structure of prealbumin (transthyretin), a protein that transports the thyroid hormone thyroxine in serum and cerebrospinal fluid. (c) Tertiary structure: Superimposed on secondary structure. α-helices and/or β-sheets are folded up to form a compact globular molecule held together by intramolecular bonds. PLAY Animation: Tertiary Structure Figure 2.19c

111 Quaternary structure of a functional prealbumin molecule. Two identical prealbumin subunits join head to tail to form the dimer. (d) Quaternary structure: Two or more polypeptide chains, each with its own tertiary structure, combine to form a functional protein. PLAY Animation: Quaternary Structure Figure 2.19d

112 Fibrous and Globular Proteins Fibrous (structural) proteins Strandlike, water insoluble, and stable Examples: keratin, elastin, collagen, and certain contractile fibers

113 Fibrous and Globular Proteins Globular (functional) proteins Compact, spherical, water-soluble and sensitive to environmental changes Specific functional regions (active sites) Examples: antibodies, hormones, molecular chaperones, and enzymes

114 Protein Denaturation Shape change and disruption of active sites due to environmental changes (e.g., decreased ph or increased temperature) Reversible in most cases, if normal conditions are restored Irreversible if extreme changes damage the structure beyond repair (e.g., cooking an egg)

115 Molecular Chaperones (Chaperonins) Ensure quick and accurate folding and association of proteins Assist translocation of proteins and ions across membranes Promote breakdown of damaged or denatured proteins Help trigger the immune response Produced in response to stressful stimuli, e.g., O 2 deprivation

116 Enzymes Biological catalysts Lower the activation energy, increase the speed of a reaction (millions of reactions per minute!)

117 WITHOUT ENZYME WITH ENZYME Activation energy required Less activation energy required Reactants Reactants Product Product PLAY Animation: Enzymes Figure 2.20

118 Characteristics of Enzymes Often named for the reaction they catalyze; usually end in -ase (e.g., hydrolases, oxidases) Some functional enzymes (holoenzymes) consist of: Apoenzyme (protein) Cofactor (metal ion) or coenzyme (a vitamin)

119 Substrates (S) e.g., amino acids Energy is absorbed; bond is formed. Water is released. + H 2 O Active site Product (P) e.g., dipeptide Peptide bond Enzyme (E) Enzyme-substrate complex (E-S) Substrates bind at active site. Enzyme changes shape to hold substrates in proper position. 1 2 Internal rearrangements leading to catalysis occur. Enzyme (E) 3 Product is released. Enzyme returns to original shape and is available to catalyze another reaction. Figure 2.21

120 Substrates (S) e.g., amino acids + Active site Enzyme (E) Enzyme-substrate complex (E-S) Substrates bind at active site. Enzyme changes shape to hold substrates in proper position. 1 Figure 2.21, step 1

121 Substrates (S) e.g., amino acids Energy is absorbed; bond is formed. Water is released. + H 2 O Active site Enzyme (E) Enzyme-substrate complex (E-S) Substrates bind at active site. Enzyme changes shape to hold substrates in proper position. 1 2 Internal rearrangements leading to catalysis occur. Figure 2.21, step 2

122 Substrates (S) e.g., amino acids Energy is absorbed; bond is formed. Water is released. + H 2 O Active site Product (P) e.g., dipeptide Peptide bond Enzyme (E) Enzyme-substrate complex (E-S) Substrates bind at active site. Enzyme changes shape to hold substrates in proper position. 1 2 Internal rearrangements leading to catalysis occur. Enzyme (E) 3 Product is released. Enzyme returns to original shape and is available to catalyze another reaction. Figure 2.21, step 3

123 Summary of Enzyme Action PLAY Animation: How Enzymes Work

124 Nucleic Acids DNA and RNA Largest molecules in the body Contain C, O, H, N, and P Building block = nucleotide, composed of N- containing base, a pentose sugar, and a phosphate group

125 Deoxyribonucleic Acid (DNA) Four bases: adenine (A), guanine (G), cytosine (C), and thymine (T) Double-stranded helical molecule in the cell nucleus Provides instructions for protein synthesis Replicates before cell division, ensuring genetic continuity

126 Phosphate Sugar: Deoxyribose Base: Adenine (A) Thymine (T) Sugar Phosphate (a) Adenine nucleotide Hydrogen bond Thymine nucleotide Sugar-phosphate backbone Deoxyribose sugar Phosphate Adenine (A) Thymine (T) Cytosine (C) Guanine (G) (b) (c) Computer-generated image of a DNA molecule Figure 2.22

127 Ribonucleic Acid (RNA) Four bases: adenine (A), guanine (G), cytosine (C), and uracil (U) Single-stranded molecule mostly active outside the nucleus Three varieties of RNA carry out the DNA orders for protein synthesis messenger RNA, transfer RNA, and ribosomal RNA PLAY Animation: DNA and RNA

128 Adenosine Triphosphate (ATP) Adenine-containing RNA nucleotide with two additional phosphate groups

129 High-energy phosphate bonds can be hydrolyzed to release energy. Adenine Phosphate groups Ribose Adenosine Adenosine monophosphate (AMP) Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) Figure 2.23

130 Function of ATP Phosphorylation: Terminal phosphates are enzymatically transferred to and energize other molecules Such primed molecules perform cellular work (life processes) using the phosphate bond energy

131 Solute + Membrane protein (a) Transport work: ATP phosphorylates transport proteins, activating them to transport solutes (ions, for example) across cell membranes. Relaxed smooth muscle cell Contracted smooth muscle cell + (b) Mechanical work: ATP phosphorylates contractile proteins in muscle cells so the cells can shorten. + (c) Chemical work: ATP phosphorylates key reactants, providing energy to drive energy-absorbing chemical reactions. Figure 2.24