BMS 300 1st Edition Lecture 3 Outline of Last 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 aquaporin1. 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 These 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.-phosphate head groups Outline of Current Lecture I. Phospholipid orientation in water -micelle -liposome -planar bilayer II. Lipid mosaic model of biological membrane -transmembrane proteinsIII. Proteins as amino acid polymers -amino acid structure 1. amine 2. carboxylic acid 3. R-group -peptide bond formation IV. Protein primary structure -amino acid sequence V. Protein secondary structure -hydrogen bonding>alpha helix>beta sheet VI. Protein tertiary structure -role of R-groups1. non-polar/uncharged 2. polar 3. charged VII. Protein folding into geometric shapes Current LectureTo recap last lecture: -remember the short hand of phospholipids as the head with squiggly tails and that the head is charged and that the tails are unchargedMicelle-circle type organization of a phosphate head groups with their heads pointed outwards towards the water and their tails pointed inward away from the water-if you put a molecule of water into the middle of the micelle it will explode because the tails are hydrophobic-not a stable stateLiposome-starts out looking just like a micelle with its tails are pointed inward -to make it a stable structure with water on the inside there are phospholipids on the inside with their tails pointing towards each other and heads pointing inward-this is stable because there is water on the inside and on the outside -the inner layer of this liposome is now called a phospholipid bilayer-width of the bilayer is in the neighborhood of about 6-7nm (way too small to function as a normal cell)***see image belowPlanar lipid bilayer -we can begin to see how we can organize the phospholipids into something closer to a real cell-the diameter of an individual phospholipid is 1nm and the width of this planar lipid bilayer is about 6-7nm whereas a cell is about 10micrometers in diameterLipid Mosaic Model of Biological Membranes-it’s called this because it has phospholipids interspersed in the transmembrane proteins and transmembrane proteins that provide communication pathways Triglycerides: hydrophobic (uncharged, water fearing) Phospholipids: amphipathic>tails: hydrophobic >heads: hydrophilic>derived from triglycerides>they stay together because they don’t want to be in the water***see image below Protein -after generating phospholipid bilayers you then have to think about how we will create proteins from weaving them across the bilayer-a protein is a polymer of amino acids linked together by peptide bonds -to make sense of what a protein is we have to look at the structure of an amino acid Amino Acid Structure-20 different R-groups (H, CH3, phenol) -the term amino acid comes from the amino and carboxcylic combined -Three different ways to determine R-groups>non-polar, uncharged, hydrophobic >polar, hydrophilic >charged, hydrophilic Peptide Bonds -amino acid sequence: determines the primary structure sequence -amino acids strung together like pop beads on a stringProtein Secondary Structure -derives from the hydrogen bonding of the protein -secondary structures of the protein do not require R-group instead arise from hydrogen bonding within the protein- hydrogen bonding occurs between the amine hydrogen and the carboxyl oxygen of other amino acids The two structure shapes:-2 helix:>steps up a spiral staircase>if you use the amino acids as “steps” each amino acid goes around a full circle>hydrogen bonding occurs around every 4th >composed by amino acids all linked by peptide bonds-beta
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