Unformatted text preview: The Chemistry of Life (7%)
I. Bonds a. Covalent i. Polar 1. Between atoms that are conversely electronegative O H ii. Non Polar 1. Between atoms that have electro‐negativities that are either about the same or the same b. Ionic 1. Between atoms that have a full charge + C C C H S S Na Cl c. Hydrogen 1. Hydrogen attached to an electronegative element (N, O) (Polar Covalent bond) 2. Causes partial positive and partial negative charge 3. Bond between second electronegative atom and H is the Hydrogen bond 4. Found mainly between nucleic acid strands §‐ §+ H O §‐ O II. pH a. Scale Acidic 0 7 Basic 14 b. Acidic i. More H+ c. Basic i. More OH‐ d. Increments i. 10x 1. i.e. pH 3 is 10x more acidic than pH 4 III. Biomolecules a. Lipids i. Mostly C‐C and C‐H bonds ii. Fats 1. Glycerol Backbone + Fatty Acid Tails 2. Saturated: Solid at room temperature a. i.e. butter 3. Unsaturated: Liquid at room temperature a. i.e. oil iii. Steroids 1. Carbon Rings + OH groups b. Nucleic Acids i. Nucleotides 1. Phosphate Group + Carbon Ring (Sugar) + Base 2. Bases attracted by Hydrogen Bonds a. A‐T (2 H bonds) b. C‐G (3 H bonds) c. A‐U (2 H bonds) c. Carbohydrates i. C‐H‐O Ratio is 1:2:1 ii. Monosaccharides 1. Glucose 2. Galactose 3. Fructose iii. Disaccharides 1. Lactose Glucose + Galactose (Hydrolysis) 2. Sucrose Glucose + Fructose (Hydrolysis) 3. Maltose Glucose + Glucose (Hydrolysis) iv. Polysaccharides 1. Starch: Plant storage form 2. Glycogen: Animal storage form 3. Chitin: Exoskeleton of insects; fungal cell walls 4. Cellulose: Plant cell wall d. Proteins i. Amino Acids 1. R group + Central Carbon + Amino Group Amino Acid 2. Amino Acid + Amino Acid Dipeptide (Condensation) 3. Combinations a. 1: Primary: Sequence of Amino Acids b. 2: Secondary: Hydrogen Bonds i. Alpha Helices ii. Beta Sheets c. 3: Tertiary: Interactions between R groups (3D) i. Ionic Bonds ii. Covalent Bonds 1. Disulfide Bonds iii. Hydrogen Bonds iv. Hydrophobic Interactions d. 4: Quantanary: Interactions between polypeptide chains ii. Enzymes 1. Accelerate rates of reactions (rxn) 2. Not destroyed in the reactions 3. Don’t change overall energetics (ΔG) 4. Lower activation energy Endothermic
Endothermic: Heat energy taken in from surroundings turned into potential energy in the products Products > Reactants The activation energy (Ea) for the forward reaction The activation energy (Ea) for the reverse reaction Enthalpy: (a): (b): Exothermic
Exothermic: Reactantʹs potential energy or enthalpy is released into the surroundings, usually in the form of heat Products < Reactants The activation energy (Ea) for the forward reaction The activation energy (Ea) for the reverse reaction Enthalpy: (a): (b): 5. Effects and Alterations a. pH i. Affect hydrogen bonding between R groups 1. Change structure b. Temperature i. Cold: 1. Enzymes not as flexible 2. Active site not able to mold around substrate ii. Hot: 1. Cause hydrogen bonds to break between R groups 2. Denaturing 3. *More collisions not necessarily going to accelerate reaction ...
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- Fall '08
- Zoology, Exothermic