BMS 300 1st Edition Lecture 2Outline of Last Lecture I. Components of water-Hydrogen and oxygen II. Structure of water III. Covalent bonds IV. Dipole moments V. Water as a liquid-Hydrogen bonds VI. Ion Solubility -Hydrophilic -Shells of hydration Outline of Current Lecture I. Ion solubility and diffusion -charged ions in water -diffusion in water -diffusion across a barrier 1. ion selective channels 2. equilibrium -water diffusion through aquaporinThese 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.1. osmosis 2. reaching equilibrium II. Hydrophobic vs. hydrophilic III. Lipids as hydrophobic molecules -triglycerides 1. glycerol (3 carbon alcohol) 2. fatty acid 3. dehydration synthesis 4. ester bonds IV. Phospholipids as amphipathic molecules -fatty acid side change -phosphate head groups Current LectureTo recap last lecture:-the positive charge of sodium interacts with the negative charge of oxygen and vice versa with the chloride -the oxygen “hogs” the electrons -the molecules are held together by hydrogen bonds -the Na+ and the Cl- charges allow for a shell of hydration around them from the water molecules-water is a polar molecule-hydrogen bonds make water liquid at room temperature -water has a dipole moment-the dipole moment allows the water to interact with the NaCl ionDiffusion:-using the same example of the water beaker image from yesterday you can see how Na+ and Cl- dissociate completely-Na+ and Cl- diffuse from higher to lower concentration which causes them to reach the equilibrium-the charge on the sodium (+) and the chloride (-) is what permits the molecules to interact with the water-the amount of grams will dissociate completely into two ions N2+ and Cl- Diffusion across a Barrier-separate the beaker into two compartments with a barrier-the right hand side contains one liter of water-the left hand side contains water, sodium ions, and chloride ions which will be randomly distributed throughout the column of water-there are no breaks in the barrier so the ions remain on the side of the barrier-then you add “ion selective channels” in the barrier one that’s chloride specific and one that’s sodium specific channel-most of the time when the ions bounce against the barrier they will just bounce back but if they hit on their ion selective channel they will go into the water on the other side of the beaker -eventually over time you will reach equilibrium between the two channels ***the randomness of this diffusion across the barriers ***how we end up reaching the equilibrium ***things move from higher to lower concentration Water Diffusion (osmosis) -barrier in the middle with the same two volumes-one side has 100mmol of NaCl -the other side only has water-the right hand side has a greater water concentration-put channels across the membrane again called water channels “aquaporin” which are water specific channels -water will move through the aquaporin in a process called osmosis***equilibrium is reached because as the water moves from right to left and fills higher and higher the left hand compartment which causes the weight of the water to offset the right and the left side of the beakerHydrophobic vs. Hydrophilic -Hydrophobic: >uncharged (lack charge)>water fearing>triglycerides: animal fats and vegetable oilEx: making salad dressing*when you mix the water vinegar and oil together droplets of oil go into the water *after it sits, a layer of oil goes to the top *oil is not soluble because it lacks charge-Hydrophilic: >charged >polar>water loving >Na+, Cl-, Ca2+, K+, ethanol (all highly water soluble)Structure & Synthesis of triglycerides-think about the structure of a triglyceride; start out with the 3 carbon structure glycerol which forms the backbone of the triglyceride-link 3 fatty acids to the glycerol to for a triglyceride (carboxylic acid) -to form a fatty acid there may be 16, 18, or 20 carbons linked to each other -the long structure is uncharged Dehydration synthesis-when you take a water molecule and combine to create a new molecule -the H from the carboxylic acid and the OH from the glycerol go together -forms a new bond called a ester bond -does the same for all three -which then creates a triglyceride -the molecule is then highly insoluble in water *SEE IMAGES BELOWPhospholipids as amphipathic moleculesPhospholipid: amphipathic molecules (amphi: both, pathic: feeling)-characteristics of lipid which makes one portion of it hydrophobic -start with the typical phospholipid and its 3 carbon backbone-on the number 3 carbon use the alcohol on the number 3 carbon and form a covalent bond, take the oxygen and link it to a O, P, and O-this is a phosphodiester bond -which causes that end of the molecule to be charged -that end is called a phosphate head groupPhosphate head groups-shorthand for phospholipid -hydrophobic tails, hydrophilic
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