09 09 2013 Biology Notes Characteristics of Life Energy Acquire and use Cells Replicate itself Evolution Information Genetic ALL Organisms are made of cells Bacteria are the smallest o 200nm wide Cells are Highly organized Bounded by plasma membrane Contain chemicals in aq solution Most can divide themselves 09 09 2013 Scientists ask questions About organisms That can be tested o By observation measurements Why are giraffes necks so long Food competition Sexual competition Perform experiments to test this hypothesis Null Hypothesis tested isn t correct In an experiment Include control groups Keep conditions constant Repeat the test more than once Only switch one condition that can be tested Specifies what should be observed when the hypothesis being 4 Main Atoms account for 96 of matter in organisms 09 09 2013 Carbon Hydrogen Nitrogen Oxygen Structure fits FUNCTION Atomic structure Protons 1 Charge o Never changes in an element Neutrons o Can vary ISOTOPES Different masses same element Can be radioactive decay over time Electrons 1 Dalton unit of mass for pro neu electrons o 6 protons 6 neutrons 12 daltons Covalent bonds shared electrons Glue atoms together Electronegativity How bad elements want their electrons Varies due to o Number of protons in the nucleus o Distance between nucleus and valance shell Causes polar nonpolar bonds O N C H Ionic bonds transferred electrons Cation charged ion Anion charged ion Molecule Models Molecular Formula Structural Formula Ball and stick Model Space filling Model 09 09 2013 WATER IS LIFE It is a great solvent dissolves substances Oxygen is partially Hydrogen partially Molecule is bent which sticks out the oxygen atom Hydrophilic water loving Ions and polar molecules stay in solution b c water s partial charges H bonding makes it possible for charged polar molecules to dissolve Hydrophobic water fearing Uncharged and nonpolar molecules hate water Do not interact or dissolve Water properties Cohesion sticks itself Adhesion sticks to other molecules Surface tension great strength of bonds on top of the surface Denser as a liquid than a solid High capacity of absorbing energy specific heat Acid base reactions Acids donate protons and increase hydronium H30 concentration Bases receive protons and decrease hydronium concentration Mole unit of molecules in a certain mass 6 022x10 23 molecules in 1 mol Molarity moles per liter pH information pH log H or H 10 pH 7 base 7 acid buffers minimize damage against ph changes 09 09 2013 Two places where early reactions could ve happened The atmosphere Deep sea hydrothermal vents Chemical Reactions Reactants start it Products are formed Proceed until an equilibrium is reached Endothermic absorbs heat during reaction Exothermic heat is released or exits ENERGY capacity to do work supply heat Exists as o Stored potential energy o An Active motion kinetic o Temperature thermal energy Transfer of thermal is HEAT 1st Law of Thermodynamics energy cannot be created destroyed Spontaneity Chemical Rxns that can occur by themselves Tend to be spontaneous when o Products are less ordered than the reactants o Products have less potential energy than reactants If electrons are held tighter less potential energy Entropy amount of disorder in a system 2nd law of thermo States o entropy always increases in an isolated system Chemical Physical processes proceed in the direction that results in increased entropy and lower potential energy 09 09 2013 Chemical Evolution Theories Top down tree of life Bottom up present in early earth Chemical evolution Models o Examine modern cells to see chemistry shared throughout the o Focus on small molecules and environmental conditions Prebiotic Soup molecules made from gases or arrived from meteorites then condensed with rain in the oceans allowing larger molecules to be constructed Surface metabolism dissolved gases touched minerals on the walls of deep sea vents and formed larger complex molecules Miller s experiment Created early earth s conditions in a flask If molecules reacted with each other the rain would carry them to the mini ocean The solution turned deep red and cloudy Found organic compounds and amino acids in there thus proving the prebiotic soup model somewhat possible The molecules needed to react with each other would be diluted so the surface metabolism method provided a solution o The minerals were on the vent walls in the ocean and would attract the gases 09 09 2013 Carbon s importance is based on its versatility Can form 4 covalent bonds because of its 4 valence electrons Limitless array of shapes can be made possible Carbo n provides the structural framework for almost all the compounds associated with life except H2O Functional Groups Carbon atoms provide the skeleton but the behavior of organic compounds are changed by groups of other elements o Such as H N O P S 6 Total Groups o Amino H2N o Carboxyl COOH o Carbonyl COH or CO o Hydroxyl OH Acts as base attracts a proton to form attracts an H Acts as an acid tends to lose a proton loses the H Polar so it makes compounds more soluble May also act as a weak acid and lose a proton Molecules with more than one P store a lot of chemical o Phosphate PO4 energy o Sulfhydryl SH Can form disulfide bonds S S that contribute to protein When you see an organic compound structure Examine size and shape by the carbon framework Locate functional groups and think about the properties of these Identify polar nonpolar covalent bonds that are formed molecules 09 09 2013 Amino Acids 20 total Structure o Hydrogen atom o NH2 amino functional group o COOH carboxyl functional group o R side group or side chain Nonpolar side chains Mostly feature C H bonds Just think about electronegativity rules o O N C H Polar side chains Look for O H bonds Look for O C bonds 5 total amino acids in this group Acidic Basic chains Look for negatively charged oxygen atoms Look for positively charged atoms Nitrogen Amino Acids to Proteins Monomers together make polymers o Polymerization reaction builds a polymer Dehydration condensation reaction remove a H2O molecule to build a polymer Peptide bond o C N covalent bond between amino and carboxyl groups Hydrolysis add a H2O molecule to separate a polymer into monomers Small chains of amino acids are oligopeptides large chains are polypeptides or proteins 09 09 2013 Primary Structure sequence of amino acids One change can cause radical changes in behavior of the protein Fundamental to higher levels of protein