BIOL 1103 1st Edition Lecture 3Outline of Last Lecture II. Historical Figures in ScienceIII. Cell Theory and the cell’s partsIV. BondsOutline of Current Lecture V. Hydrogen Bonds and PolarityVI. IsotopesVII. Water Molecules and Basics of pHCurrent Lecture- 1953 marked the beginning of modern biology with the discovery of the double helix (DNA)- Hydrogen bonds/polarity:o Hydrogen bond = attraction between hydrogen atoms with a partial positive charge and a partial negative charge; attraction between polar moleculeso Nonpolar molecules have symmetric chargeso If a molecule is nonpolar, it will not dissolve in watero Electrons are shared equally between nonpolar molecules- Isotopes:o Ionic bonds= gain or loss of an electrono Isotopes= atoms that have the same atomic number but differ in atomic mass because they have a different number of neutronso Radioactive isotope= any of several species of same element with unstable nuclei- Carbon-14 is the best element for dating things- Free radical = atom or molecule that has a single unpaired electron in outer shell- Water and pH:o In a salt water mixture, for example: Solute = what is being dissolved (salt) Solvent = what is doing the dissolving (water) Solution = homogeneous mixture (salt water)o Living things are 75-95% waterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Earth’s surface is 71% watero Human body holds 66% water weighto Water molecules bead up because of their polarity o Water molecules stick together and form a liquid state because of hydrogen bondso Temperature can cause water molecules to move so fast that they break off from each other and form gaso Ice = water molecules bounded by hydrogen bonds that are stableo Polar water molecules separate sodium and chloride and that’s why it dissolves Attraction separation dispersiono pH is a measure of hydrogen ion concentration o 7 on pH scale is neutral (water)o Hydrogen and hydroxide ions in equilibrium in water that is 25 degrees Celsius o >7 = basic (blood)o <7 = acidic (our
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