BIOL110s05-07 - BIOL 110 Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 7, W 2/2/05 Dr. Nathan Staples (Ph.D., UCSB 2002) Don't forget to read and prepare Pre-Lab writeups for Mon./Wed. Labs (What? Why? & How? are we doing in the lab?) Midterm #1: Next Friday, 2/11. (Ch. 1-3) REVIEW: Ch. 2: The Molecules of Life chemistry Bonds = covalent (polar, nonpolar), hydrogen Water Acids, Bases TODAY: Ch. 2: The Molecules of Life chemistry Organic molecules: Macromolecules carbohydrates, lipids, proteins, nucleic acids. 1 Acids and Bases Acids Donate H+ when dissolved in water Acidic solutions have pH < 7 Bases Accept H+ when dissolved in water Acidic solutions have pH > 7 C. Buffer System Minimizes shifts in pH Is a partnership between a weak acid and the base it forms when dissolved The weak acid and base work as a pair to counter shifts in pH 2 Carbonic AcidBicarbonate Buffer System When blood pH rises, carbonic acid dissociates to form bicarbonate and H+ H2CO3 HCO3- + H+ When blood pH drops, bicarbonate binds H+ to form carbonic acid HCO3- + H+ H2CO3 D. Salts Compounds that release ions other than H+ and OH- when dissolved in water Example: NaCl releases Na+ and Cl Many salts dissolve into ions that play important biological roles Sodium, Potassium, Calcium, Magnesium.... 3 V. Organic Compounds Hydrogen and other elements covalently bonded to carbon 1. 2. 3. 4. Carbohydrates Lipids Proteins Nucleic acids = Carbon's Bonding Behavior Outer shell of carbon has 4 electrons; can hold 8 Each carbon atom can form covalent bonds with up to 4 atoms Versatile bonding properties!!!!!! Arrangements: chains, "rings", rings" multi-branched structures multi Other atoms project from the carbon backbone Glucose (ball-and-stick model) 4 Functional Groups Atoms or clusters of atoms that are covalently bonded to carbon backbone Give organic compounds their different properties E.G.: Methyl group Hydroxyl group Amino group Carboxyl group Phosphate group Sulfhydryl group CH3 OH NH3+ COOH PO3SH Types of Reactions 1. Functional group transfer 2. Electron transfer 3. Rearrangement 4. Condensation (eg: Synthesis) 5. Cleavage (eg: Hydrolysis) 5 1. Condensation Reactions Form polymers from subunits (monomers) ANABOLIC reactions Enzymes remove OH from one molecule, H from another (releasing H2O) form bond between two molecules Discarded atoms can join to form water 2. Hydrolysis A type of cleavage reaction "Splitting with Water"!! Breaks polymers into smaller units CATABOLIC reactions Enzymes split molecules into two or more parts An OH group and an H atom derived from water are attached at exposed sites 6 A. Carbohydrates 1. Monosaccharides Simple sugars Glucose, fructose, ribose 2. Oligosaccharides Short-chain carbohydrates Sucrose, lactose, maltose glucose fructose 3. Polysaccharides Complex carbohydrates Glycogen, starch, cellulose, chitin Sucrose Formation Condensation: Glucose (monosaccharide) Fructose (monosaccharide) + H2O Sucrose (disaccharide) 7 Major Polysaccharides Chitin Biochemical Structure Determines Biological Function!!! cellulose glycogen amylose (a starch) B. Lipids Tend to be insoluble in water HYDROPHOBIC 1. 2. 3. 4. Fats Phospholipids have fatty acid tails Waxes Sterols: have a fused carbon ring 8 1.) Fatty Acids Carboxyl group at one end Carbon backbone Saturated or unsaturated stearic acid linolenic acid 2.) Fats & Oils Fatty acid(s) attached to glycerol Triglycerides are most common glycerol three fattyacid tails 9 3.) Phospholipids Main component of cell membranes Hydrophilic head Hydrophobic tails Hydrophilic "heads" Hydrophobic "tails" Hydrophilic "heads" Sandwich! 4.) Sterols and Derivatives No fatty acids Rigid backbone of four fused-together carbon rings Cholesterol: most common type in animals Vitamin A, D, E, K Estrogen, Testosterone Cholesterol 10 5.) Waxes Long-chain fatty acids linked to longchain alcohols or carbon rings Firm consistency, repel water Important in waterproofing Structure Determines Function!!! C. Proteins: Amino Acid Structure Carboxyl group Amino group R group tryptophan (trp) 11 Protein Synthesis Peptide bond Condensation reaction links amino group of one amino acid with carboxyl group of next Water forms as a by-product by- 1.) Primary Structure 1. Sequence of amino acids 2. Unique for each protein 3. Two linked amino acids = dipeptide 4. Three or more = polypeptide 5. Backbone of polypeptide has N atoms: -N-C-C-N-C-C-N-C-C-N- 12 ...
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This document was uploaded on 03/18/2010.

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