BIO 151 1st Edition Lecture 6 Outline of Last Lecture 1. Carbohydrates2. Polysaccharides3. Summary4. Proteins5. Polymerizing proteins6. Secondary, tertiary, and quaternary structures7. Primary structure8. Secondary structure of protein9. Tertiary structure10. Quaternary structure11. How many, how big?Outline of Current Lecture 1. Protein structure and shape2. Almost all enzymes are proteins3. Proteins can be...4. Protein folding can be altered5. Shape changes can cause disease6. Membranes7. Lipids8. Membrane lipids9. Hydrophobic interactionsCurrent Lecture Protein structure and shape:- primary - sequence of amino acids- secondary - folding of polypeptide chains into alpha helix or beta pleated sheets- tertiary - other types of folding- quaternary - binding between different polypeptidesAlmost all enzymes are proteins:- due to "lock and key" interactions with reactions- proved in 1920s and 30s - another Nobel Prize- single proteins often have several domains, each with own folding (and thus structural, binding and/or enzymatic properties)- can predict (sometimes) by feature of primary (amino acid) sequenceThese 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.Proteins can be...- 1. enzymes - catalyze chemical reactions- 2. structures - blobs, fibers, jellies, etc.-Ex. collagenProtein folding can be altered:- loss of secondary-tertiary-quaternary structure - denaturation- non-peptide bonds sensitive to temp., pH, salt concentration, etc.- consequence of denaturation - enzymes work best at particular temp., pH, etc.Shape changes can cause disease:- hemoglobin - protein that binds oxygen in blood cells- sickle cell anemia - difference in one amino acid in hemoglobin- 3. pumps, motors - due to regulated changes in shape-muscles move due to changes in proteins- 4. switches - regulators of cell function, other proteins-protein activity also sensitive to binding, chemical modifications-Ex. binding of regulators of enzyme inhibit its activity by:-blocking the active site (competitive inhibitor)-changing the enzyme's shape (conformation) = allosteric interaction (noncompetitive inhibitor)Membranes:- a cell is a bag for chemical reactions to happen- membranes define the boundaries of a cell- cell membrane (plasma membrane)- intracellular (inside) = cytoplasm (cytosol)- extracellular cell wall or extracellular matrix (outside)Lipids:- contain hydrophobic hydrocarbon atoms- not water soluble- store and release energy (fats) - more energy in C-H bonds of hydrocarbons than C-O bonds of carbohydrates- signaling between cells (especially steroids)- form lipid bilayer membranesMembrane Lipids:- majority are phospholipids- polar "head" with phosphate (PO4) link to one of several polar molecules- glycerol link to 2 nonpolar fatty acid hydrocarbon "tails"- bilayer - forms a sheetHydrophobic Interactions:- hydrophobic molecules (or parts) hide from water with other hydrophobic
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