L48 Anthro 209C Lecture Notes - Lecture 1: Lipid Bilayer, Chitin, Cell Nucleus
10 Sep 2017
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Atom: defined by number of protons in nucleus (hydrogen=1 proton) Electron cloud/shield mass equal equal tiny electrons stay in cloud because attracted to positive protons in nucleus. Ion: atom or molecule with different number of electrons. Covalent: share e- (strongest bond, can"t be broken by water// not dissolvable) For atoms to be stable outer shell must be full, sharing electrons allows two atoms to have full outer shells. Ionic: transfer e- (relatively strong but breaks in water) Sodium chloride -> salt held in crystal by + sodium and - chlorine. Pos/neg region in molecule holds things together but entire molecule can be pos/neg/neu. Shape bc oxygen and hydrogen not sharing e- equally (oxygen stronger bc more protons so pull e- more/spend more time by oxygen than hydrogen) Slightly pos and slightly neg regions so things that dissolve have some charge (sugar, salt, protein dissolve in water but fats and lipids don"t bc no + or - region)
