CHEMICAL BONDS. Attraction that holds molecules together Involves valence electrons. Ionic Bonds Covalent Bonds. Involves sharing of.

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1 CHEMICAL BONDS DEFINITION/DESCRIPTION: Attraction that holds molecules together Involves valence electrons TYPES: Ionic Bonds Covalent Bonds Involves sharing of electrons Electronegativities O = 3.5 N = 3.0 C = 2.5 H = 2.1 Transfer of electrons from one atom to another Difference in electronegativity is high Electronegativity = atom s ability to attract and hold electrons Forms ions Cations = positive ions Anions = negative ions Weak bonds in solution Nonpolar = electrons shared equally C-C or C-H Small or no difference in electronegativity Polar = electrons NOT shared equally C-O or H-O Difference in electronegativity is larger than nonpolar but smaller than ionic TYPES: Page 1 of

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3 WATER, ACIDS, BASES, BUFFERS Page 3 of

4 PROPERTIES OF WATER: Liquid water is cohesive Cohesion = H bonds between water molecules; H2O molecules tend to stick tog. Importance = Transport H2O against gravity in plants Higher surface tension Water has a high specific heat Takes a lot of energy to raise 1 gram of H2O 1 o C Why? Must break H bonds Liquid H2O can absorb large amounts of heat with small changes in temperature Water has a high heat of vaporization Takes a lot of energy to convert liquid H2O into vapor Why? Must break H bonds Keeps water in liquid state Water expands with it freezes Solid H2O is less dense than liquid H2O Why? In solid state H2O locked into max. number of H bonds; takes up more space Water is a versatile solvent Will dissolve polar covalent and ionic compounds Page 4 of

5 DISSOCIATION OF WATER: H 3 o H 2 O + H 2 O + OH- H+ H 2 O + OH- Hydronium ion Hydroxide ion 1 out of 554,000,000 water molecules dissociates At equilibrium in pure water at o C [H+] = [OH-] = 1.0 x 10-7 M If add [H+] to pure water If add [OH-] to pure water Removes OH- Removes H+ Equilibrium shifts left Equilibrium shifts right [H+] > [OH-] [OH-]>[H+] reduces H+ indirectly If add NH3 NH3 + H+ NH4+ Reduces H+ directly PH SCALE: ph = -log10[h+] [H+] x [OH-] = If [H+] = 10-7 If [H+] = 10-9 Then [OH-]=10-7 Then [OH-] = 10-5 ph = 7 poh=7 ph=9 poh=5 Page 5 of

6 BUFFERS: Description Function Importance Weak acids or bases Minimize changes in ph Controls chemical reactions Maintains homeostasis BICARBONATE BUFFER SYSTEM: H2O + CO2 H2CO3 HCO3 + H + HCO3- = Bicarbonate (weak base) H2CO3 = Carbonic acid (weak acid) Major buffer system in blood Maintains blood ph between 7.38 and 7.42 Action: Increase [H + ] How? Fat metabolism OD on acidic drug Effect: Increase [H+] Equilibrium shifts left H+ + HCO3- H2CO3 CO2 + H2O Increase [CO2] Increase rate and depth of respiration Increase Rate & Depth of Respiration Hyperventilate Decrease [CO2] (CO2 is acidic) Equilibrium shifts right H+ + HCO3- H2CO3 CO2 + H2O Blood ph increases Page 6 of

7 PROPERTIES OF CARBON: Has 4 valence electrons Form 4 covalent bonds (single, double, triple) Carbon chain Straight, branching, ring Varies in length, number and location of double bonds, and presence of other elements Forms isomers C 6 H 12 O 6 chemical formula for glucose, fructose, & galactose CARBOHYDRATES General Characteristics - Polymers of Simple Sugars - Classified according to number of simple sugars - Sugars carbons C 6 H 12 O 6 Page 7 of

8 Functional Groups: Affect a molecule s function by participating in chemical reactions. FUNCTIONAL GROUP Hydroxyl Carbonyl DRAWING/FORMULA PROPERTIES Polar Water soluble Alcohols Polar Water soluble Carboxyl Polar Water soluble Acid Amino Polar Water soluble Weak base Sulfhydral Phosphate Form disulfide bridges Stabilize protein shape Polar Polar Water soluble Acid Important in energy transfer Page 8 of

9 FUNCTIONAL GROUP Methyl DRAWING/FORMULA PROPERTIES Nonpolar Not water soluble MONOSACCHARIDES: Simple sugars Monomers of di- and polysaccharides Store energy in chemical bonds Trioses 3-carbon sugar glycerahdehyde Pentose 5-carbon sugar Ribose Deoxyribose Hexose 6-carbon sugar Glucose Fructose Galactose Glu cose Linear form (dry) Glucose Ring form (in sol n) Page 9 of

10 DISACCHARIDES: Double Sugars Condensation Synthesis: Removal of water molecule to form bond between monomers Hydrolysis: Addition of water to break bonds Glucose + Fructose Sucrose + water Glucose + Glucose Maltose + water Glucose + Galactose Lactose + water POLYSACCHARIDES: Many monosaccharides covalently bonded together FUNCTIONS: Storage Starch: storage carb. in plants Glycogen: storage carb. in animals STARCH VS CELLULOSE Starch branched chains of GLC Structural Cellulose: plant cell wall component Chitin: polymer of amino sugar Building block of exoskeletons Cellulose unbranched chains of GLC Most animals lack enzyme to break Page 10 of

11 LIPIDS General Characteristics: Not soluble in water Mostly hydrocarbon chains Fats, steroids, phospholipids Building Blocks: H 2 Fats: Glycerol + fatty acids Triglycerides have 3 fatty acids Fatty acids present may vary Compact energy source Cushions vital organs Provides insulation Page 11 of

Saturated: No double bonds between carbons Straight

between carbons Hydrocarbon chain is bent Usually solid

packing Most animal fats Usually liquid at room

12 Saturated: No double bonds between carbons Straight chain Fatty acid Unsaturated: At least 1 double bond between carbons Hydrocarbon chain is bent Usually solid at room temperature Straight chains allow for tight packing Most animal fats Usually liquid at room temperature Bent chain prevents tight packing Most plant fats Page 12 of

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support Storage of amino acids Receptor proteins; contractile proteins; antibodies;

14 PROTEINS GENERAL CHARACTERISTICS AND IMPORTANCES: Polymers of amino acids Each has unique 3-D shape Vary in sequence of amino acids Major component of cell parts Provide support Storage of amino acids Receptor proteins; contractile proteins; antibodies; enzymes UILDING BLOCKS: Amino acids 20 different amino acids ANION CATION DIPOLAR ION Page 14 of

15 PEPT IDE BONDS : Page 15 of

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DENATURATION: Changing protein s native conformation Change shape = change in activity How? 1. High temperature 2. Chemical agent (acid or base) change in ph 3.

17 DENATURATION: Changing protein s native conformation Change shape = change in activity How? 1. High temperature 2. Chemical agent (acid or base) change in ph 3. Organic solvent ENZYMES Enzyme-Protein that functions as biological catalyst Catalyst-substance that speeds up the rate of a chemical reaction without being altered or consumed in the reaction; decreasing the amount of energy needed in the reaction. Functions: -facilitate chemical reactions Reactants (substrates) Products -important for maintaining homeostasis -without enzymes life would occur too slowly to maintain life. Page 17 of

18 DNA STRUCTURE AND REPLICATION BUILDING BLOCKS OF DNA: Nucleotides: 1. 5 carbon sugar (deoxyribose) 2. Nitrogenous base (A, T, C, or G) 3. Phosphate group NITROGENOUS BASES PYRIMIDINES Single ring structure C and T PURINES Double ring structure G and A Cytosine Guanine Thymine Adenine Page 18 of

19 DNA STRUCTURE Page 19 of

20 ANTIPARALLEL STRANDS One strand 5 at top & 3 at bottom Other strand: 5 at bottom & 3 at top 5 end 5 th carbon in deoxyribose Nucleotide 3 end 3 rd carbon in deoxyribose Page 20 of

21 LAWS OF THERMODYNAMICS ATP Carries Energy First Law Energy cannot be created or destroyed Energy can be transferred and transformed Second Law Every energy transfer makes the universe more disordered Entropy = measure of disorder Whenever energy is transferred some is lost as heat Amt of useful energy decreases whenever energy is transferred PROBLEM Living organisms are highly ordered; decrease entropy Question: Do living organisms violate the 2 nd law? ANSWER No Living organism is a closed system Must consider organism & environment Living organisms Maintain highly ordered structure at expense of increased entropy of surroundings Take in complex high energy molecules, extract energy, release simpler, low energy molecules (CO2 and H2O) and heat to environment EXERGONIC REACTIONS Page 21 of

22 Reactants have more energy than products More ordered to less Unstable to stable Downhill reaction Free energy released Spontaneous Examples Cellular respiration Digestion ENDERGONIC REACTIONS Products have more energy than reactants Less ordered to more Stable to unstable Uphill reaction Free energy absorbed from surroundings Examples Photosynthesis Polymer synthesis Page 22 of

23 COUPLED REACTIONS Energy released from exergonic reaction drives endergonic reaction Exergonic Reaction G = max. work that can be done Endergonic Reaction G = min. work needed to drive reaction ATP Adenosine triphosphate Has unstable phosphate bonds Page 23 of

24 ATP STRUCTURE Unstable, high - energy bonds Adenine Phosphate groups Ribose (5 - C sugar) Page 24 of

25 HOW ATP DOES WORK TYPE OF WORK Mechanical Transport Chemical DESCRIPTION Beating cilia Muscular contraction Movement Active transport Pumps (H+ and Na+/K+) Endergonic reactions Polymerization Page of

The Chemistry and Energy of Life

2 The Chemistry and Energy of Life Chapter 2 The Chemistry and Energy of Life Key Concepts 2.1 Atomic Structure Is the Basis for Life s Chemistry 2.2 Atoms Interact and Form Molecules 2.3 Carbohydrates