Week 7 Lecture Notes
Week 7 Lecture Notes BCH 110
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This 5 page Class Notes was uploaded by Cassidy Zirko on Wednesday March 9, 2016. The Class Notes belongs to BCH 110 at University of Montana taught by Scott Samuels in Spring 2016. Since its upload, it has received 9 views. For similar materials see Intro Biology for Biochemist in Biology at University of Montana.
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Date Created: 03/09/16
Enzymes 3/7/16 Reaction rate and direction are different Biological reactions are catalyzed by enzymes Enzymes as biological catalysts o Most enzymes are proteins, some catalytic RNA o Enzymes increase the rate of reaction m o Enzymes are very specific some only catalyze reaction of one stereoisomer Activation energy o Determines rate of reaction o Transition state is at energy minimum o Enzymes provide alternate pathway with lower activation energy o Enzymes provide alternate energy route o Binding and stabilizing transition state Temperature effect o Increases reaction rate o Heat can denature proteins, too much heat causes lack in reaction Substance binding o Reactant is the same thing as a substrate o Active site wehre substrate binds to enzyme via multipole weak interactions o Substrate binding is the first stop in the reaction Binding Model o Lock and key substrate fit into enzyme like key into lock o Induced fit model binding of substrate changes shape of enzymes causing conformational changes o Substrate binds o Transition state is formed o Catalysis: bond rearrange o Product is formed and released o Weak interactions allow for release of product o Some have covalent catalysis Phosphorylation o Transfer of phosphate from ATP to hydroxyl group of serine, threonine or tyrosine o Regulates activity o Catalyzed by proton Kinases o Hydrolysis is catalyzed by phosphates o Adding a lot of a negative charge o Can effect many parts of reaction o Kinases are major regulators o Covalent modification because of bonding o Removing phosphate by phosphatases o ATP is energy current o Removing phosphate universe is happy because negative is not next negative and have a higher entropy Sodium potassium pump o Sodium and potassium and ATPase o Phosphorylation coupled to conformational change in protein that pumps ions across membrane against concentration gradient o Pumps use energy from ATP sodium out and potassium in Coenzymes o Cofactors nonprotien structures that participate in enzymatic reactions and are regenerated Metal ions: behaves as coordination compounds Coenzymes: organic compounds, vitamins or derived from + NAD nicatinamide adenine dinucleotide o Coenzymes used in redox reactions o NAD /NADH used in a redox reactions o NAD is 2 electron oxidizing agent that is reduced to NADH B 6vitamins o Coenzymes involved in amino group transfer from one molecule to another o Important in amino acid synthesis Lipids 3/9/16 Amino acids are not macromolecules Lipids are polymers Lipids o Heterogeneous group of compounds that are insoluble in water but soluble in nonpolar organize solvents o Open chain fatty acids, tryclycerols and others o Cyclic forms cholesterol, steroid hormones, bile acids Hydrophobic interactions weak interactions between nonpolar groups Hydrophobic interactions are driven by entropy want to get ride of water Lipid function o Fats store energy (long term) o Steroids cholesterol (biomembrane fluidity), hormones o Phospholipids biomembranes structure Fatty acid o Amphipathic compound with a polar head and nonpolar tail o Polar head carboxylic acid o Nonpolar tale hydrocarbon chain o 2 main parts o Carboxylic head charged under neutral conditions o Amphipathic structures drive membrane structure o Saturated fatty acid all single bonds o Unsaturated: Carbon, carbon double bond 1 double bond monounsaturated More than 1 double bond polyunsaturated Double bond on the same side create bend in molecule Trans molecules aren’t bent Trans fatty acids are very bad for you o Saturated vs. unsaturated only considering double bonds or not o Bend or straight structures determine fluidity Melting point o Depends on the number of double bonds and length o Longer chains mean higher melting point o Amount of double bonds creates a longer chain lower melting point Triaglclycerols o Ester of glycerol with there fatty acids o Stores excess energy o Oxidation of fat releases twice as much energy and oxidation of carbs Soaps o Sodium or potassium salts of fatty acids o Saponification: treat triacylglycerols with sodium hydroxide and potassium hydroxide o Soaps form water, water soluble when used in hard water o Hard water high in calcium and magnesium Phospholipids o One alcohol group of glycerol is esterified to phosphoric acid o Major lipid component of most biological membranes many types base on R groups Membrane o Hydrophilic groups face both interior and outside of cell o Interior is hydrophobic parts Glycolipids o Carb bound to hydroxyl group of lipid o Sugar is glucose or galactose o Involved in cell and tissue recognition, like ABO blood type o Involved in antigens Steroids 3/11/16 Steroids o Group of lipids with fused ring structure of three six membraned rings and 1 5 membraned right o Basis of cholesterol Polar components is one hydroxyl and is highly hydrophobic Important in maintaining animal cell membrane fluidity Acts amphipathic o Sex hormones are steroids Androgen: Male sex hormone Estrogens: Female sex hormones Control of menstrual cycle Biological Membranes Cellular membranes o All cells have plasma membrane separates inside from outside o Controls transport of substances in and out o Eukaryotic cells membrane enclosed organelles Lipid bilayer structure o Polar head contact with aqueous environment o Nonpolar tails buried within bilayer o Major force driving formation of a lipid bilayer hydrophobic interactions o Fluidity of bilayer interior depends on types of fatty acids and temperature Double bonds in nonpolar tails increase fluidity Lipid bilayer asymmetry o Lipid composes inner and outer of leaf let lipid bilayers be different o Bulker heads group in outer shell o Smaller heads on interior, creates curvature o Hydroxyl group of cholesterol face either interior or exterior of cell o Cholesterol is very stiff Saturated fats are long and stiff Kink in unsaturated fatty acids allow fluidity Plants have phytosterols, fungi have ergosterols equivalent of cholesterol Cholesterol buffers fluidity o Reduces fluidity by stabilizing extended chain conformations of the hydrophobic tails o Increases fluidity by preventing interactions between hydrophobic tails Lipids and Membrane Fluidity o Interactions between hydrophobic tails decreased fluidility o Shorter tails have fewer interactions o Unsaturated fatty acids kincked decrease interactions Transition temperature o Gel to liquid crystalline phase transition Membrane proteins o Integral embedded in phospholipid bilayer o Peripheral weakly bond to membrane o Lipid linked covalently attached to lipid o Lipid linked used by bacteria Integral membrane proteins o Tightly bound to membranes by hydrophobic interactions o Can separate from membrane only by reactions that disrupt membranes Peripheral membrane proteins o Attached to membrane by binding at surface usually to integral membrane lipid linked o covalently linked to a lipid that anchors protein to the membrane Fluid Mosaic Model o Fluid lateral motion of proteins and lipids in plan of membrane o Mosaic proteins in lipid bilayer o May have protein structured into membrane o Outside has glycolipids involved in signaling sugars o Glycolipids antigens involved in determining a cell verses a noncell
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