BOT 200 Chapter 2
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This 4 page Class Notes was uploaded by Keely Egelhoff on Friday September 9, 2016. The Class Notes belongs to 200 at Western Illinois University taught by Dr. Meiers in Fall 2016. Since its upload, it has received 15 views. For similar materials see Introduction to Botany in Botany at Western Illinois University.
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Date Created: 09/09/16
Chapter 2 Chemicals Bonds Neutrons only affect the weight of an atom Anion- atom or molecule that carries a charge is an ion, negative Cation- positive ion Electronegativity- electrons to move tot eh most stable position configuration driving force behind chemical reactions - Fluorine- great affinity for electrons, 4.0 - Noble gases have no affinity, 0.0 More stable means atoms have less energy Exergonic- less energy when liberate to surrounding Exothermic- energy released as hear Covalent bonds- electrons share with other atoms Ionic bonds- do not share electrons they take them Polar molecule- slightly negative and positive on the ends Hydrogen bonging- positive end attracts the negative end Nonpolar molecules- not balanced 1. Water solubility and lipid solubility Water soluble- when substances dissolve Lipid soluble- nonpolar substances dissolve in other nonpolar chemicals 2. Acids and Bases Acidity- the concentration of H+ measured as pH Acid- any substance that increases the concentration of free protons Base- anything that decreases the concentration of free protons IF a nonpolar water insoluble molecule picks up a proton because an acid is present the non-polar molecule becomes positively charged and water soluble. Carbon Compounds Fatty acids- most carbon atoms share two electrons with each of two hydrogens and each of two more carbons Single bond- contains one electron and one from another atom, arragned in a tetrahedron, carbon backbone is zigzagging not straight Double bond- sharing two electrons with one atom, two sets of double bonds produce a straight molecule - If one double bond and two single bonds are present, the molecule is flat and shaped like a Y - Cis position when both Xs on the same side - Trans position when on opposite sides Second-order Reactions Two molecules react to form a third Must collide violently cannot just be near each other, will not share electrons only passed through the orbitals, speed=heat- kinetic energy Activation energy- energy needed to overcome electron-cloud repulsion and permit chemical reaction If they have enough kinetic energy (moving fast enough) they will push close together instead of repelling themselves Exergonic- energy liberating electrons are more stable (have less energy) in new boding than the old non-boding Little moving will happen at low temp but a lot of moving and colliding will happen at a high heat Catalysts Allows a reaction to occur even if the setting is not right In all living things catalysts are proteins called enzymes Catalyst is not altered itself during a reaction First- Order Reactions First-order reaction only uses one molecule not the collision of two AB- A+B Compound breaks down into two parts Can be accelerated by heat or catalysts Functional groups Small number of families make up functional groups Attach to carbon atoms can have lots of functional groups being both acidic and basic or lipid soluble and water soluble in others Polymeric Construction Polymer- large compound composed of a number more or less identical subunits(monomers) Reduces the difficulty of construction With sugars for the plant to make starch it bonds glucose together with a certain type of bond to make cellulose Allows organisms to have a simple basic metabolism that produces only a few types of monomers Allows for recycling and conservation of resources After polymers are no longer need it is depolymerized back to its monomers Allows various parts of an organism to work together in construction Carbs Usually only contain carbon, hydrogen, and oxygen Can contain nitrogen or sulfur Ratio of Hydrogen to Oxygen is 2:1 Monosaccharides Simplest carbs- simple sugars Classified by number of carbon atoms four- tetrose, five (pentose), six (hexose), seven- carbon sugars Pentose and hexoses most abundant and important They are flexible because of their carbon-carbon are single bonds When one end of a molecule comes close enough to the other end the two may react forming a closed ring The ring form is more stable Because of ring formation monosaccharides tend to be rather unreactive relatively inert molecules ideal for construction transport and energy storage Most plants use sucrose, disaccharide composed of one glucose and one fructose Polysaccharides Monosaccharides can act as monomers reacting with other monosaccharides to form polymers called polysaccharides Oligosaccharides- extremely short polysaccharides less than 10 monos long named by the number of sugars they contain Dehydration reaction- During bond formation an entire -OH is removed from one carbon a Hydrogen is removed from the other -OH group and water is formed Hydrolysis- reversal of this breaking the bond by adding water back to it Only a few exist Energy of activation barrier of polymerization is high must be catalyzed by and enzyme Starch- amylose and amylopectin is a long polysaccharide composed only of glucose residues Starch synthetize recognizes only glucose Alpa-1 4 glyosidic bond both glucoses are facing the same way Glucose residue nor fully complete glucose No branching is amylose Highly branched molecule is amylopectin Starch serves a long time storage of energy Proteins Unbranched polymers are amino acids 20 amino acids are used for protein synthesis 1(-COOH) carboxyl group causes it to an acid -NH2 the amino group -H “R” that differs from one amino acid to another structurally, chemically, and biological Levels of Organization in Protein structure Amino acid sequence is the primary structure Alpha Helix is when protein forms a helical structure also a secondary structure Folded fat areas are called beta pleated sheets Physical shape of a protein in a functional shape is tertiary structure Positively charged regions attract and bind to negatively charged regions Structure is also affected by pH and heat If heated enough proteins will unfold and be denatured Quaternary structure refers to the interaction between two or more separate polypeptides Maintained by hydrogen bonding Only when all polypeptides are aggregated the active sites are completely formed and functional Allows for self-assembly of certain structures automatically associate into the proper structure such as a microtubule or an enzyme complex Nucleic acid Are polymers composed of monomers called nucleotieds Boding of a phosphate group, a five carbon sugar and a complex ring Pyrimidines composed of a single ring Purines consist of two rings Ribose and deoxyribose are five carbon sugars Only four ribonucleotides occur because thymine is not attached to ribose Uracil is not attached so only 4 deoxy ribonucleotides occur DNA RNA found in nucleus Lipids Fats and oils substances Hydrophobic and water insoluble Fatty acids are the basic unit If every carbon atom except the carboxyl carbon carries two hydrogens the fatty acid is saturated Stabilized makes it hard to break down or melt Double bonded to adjacent carbons make it unsaturated
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