BIOL 541 1st Edition Lecture 15 Outline of Last Lecture I. Glycolysis in liver. Outline of Current Lecture II.TCA cycleIII. Structure of mitochondriaIV. ETCCurrent LectureBiochem Lecture 15- TCA cycle:Isocitrate dehydrogenase: It is a special isozyme in the fat tissues. NADP isocitrate dehydrogenase uses NADP instead of NAD. Generally, NAD is for catabolic pathway but in fat NADPH is for fatty acids. A lot of it comes from PPP. Fat tissues have isozyme and uses NADPH for fat synthesis. Proto-oncogene is a normal gene whereby mutation induces tumor, in other words becomes tumorgenic. Growth factor receptors such as TYR kinase leaves for cell proliferation. Receptor becomes constituently active and uncontrolled proliferation.Iso citrate dehydrogenase which is a protooncogene, upon mutation causes the formation of 2, hydroxyl glutarate into alpha hydroxyl glutarate. It is a brain tumor where the neurotransmitter acts as a growth promoter.Reaction: CO2 is removed. Oxidation and decarboxylation converts ketone to carboxylic acid.Regulation:Low levels of NADH and ATP brings about an increase in the cycle.The product succinyl COA level increases, thereby decreasing the cycle which is stimulated by Ca. 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.Any COOH attached either to phosphate or sulphur is a high energy bond that is donated by ~. These high energy bonds make ATP.Substrate level phosphorylation gives succinate.2C’s are removed and hence oxaloacetate needs to be regenerated.Therefore, C needs to be oxidized to ketone.Succinate dehydrogenase pulls H to form = bonds. FAD is the H acceptor. Regulation is by acetylation where when acetylation increases, NAD increases and deacetylase decreases.Fumarase adds water across = bond and forms malate.Malate dehydrogenase adds H to ketone thus oxaloacetate is made.TCA:2 C’s removed as CO2.3 reduced NADH1 reduced FAD and 1 substrate level phosphorylation/ acetate formed.Trace C in TCA: Oxaloacetate ------ acetyl COA --- citrate ---- isocitrate- alpha ketoglutarate ----- succinate --- original C from acetyl COA stayed --- malate ---- 2C leavesto add acetate.1. Rid of 2C and regenerate oxaloacetate.2. Modification of TCA cycle (catabolic pathway). Plants do not need TCA cycle for energy. Photosynthesis is present to generate metabolic intermediates.Glcoxylate Pathway ( same as TCA in plants).Acetate to glucose ( animals can not do that. Acetyl COA + oxaloacetate ----- citrate synthase ----- aconitase --- isocitrate ( OH removed and CO2 removed ).Instead:Isocitrate lyase splits in 2C to produce succinate and lower portion is gloxylate.Next, acetyl + CO2 coupled to glycoxylate which is converted to malate by malate synthase. OH is attached to ketone to form oxaloacetate.Glycoxylate Pathway:2 acetyl COA ---- succinate 4C . This reaction occurs only in plants and bacteria.Metabolon: Cyclic: Assembly line:Citrate synthaseAconitaseAlpha keto dehydrogenaseSuccinate COA synthaseSuccinate dehydrogenase (membrane electrons fed directly into ETC).Fumarase (adds water across = bonds)Malate dehydrogenase (OH group).ATP + H , H + O2 --- ETC.Structure of mitochondria:Double membrane bounded organelle. Symbiotic bacteria (eukaryotes and prokaryotes).Eukaryotes- outer membrane.Prokaryotes- inner membrane.Outer membrane is smooth as it contains 50% lipids and 50% proteins.Inner membrane is rough with high protein percentage of 75%. The high level of protein accounts for thepresence of being highly packed with ETC as there is lower lipid content. Increasing the lipid content decreases the efficiency of ETC.There are many folds of membrane called as cristae that increase the surface area as seen in micro villi for increasing absorption.Inner membrane has ETC where FAD linked succinate dehydrogenase is present.ATP synthase also present to make ATP. Material in the center is mitochondrial cystol. The matrix has enzymes for TCA cycle where B- oxidation of fatty acids and oxidation of amino acids occurs. All oxidation reaction occurs in the mitochondria. Mitochondria has its own DNA and still codes for protein coding where RNA is present for transcription and translation of protein occurs.ETC:Electrons enter ETC with lots of energy. Electrons are handed down from one protein to another. One level below has less energy from the level above. Down hill motion harvests energy: In form of powering H pumps electrons flow down and they power H pumps.Half reactions:½ O2 + NADH + H ------ H2O + NADE = [ 2H + ½ O2] – [NADH + H] = = 0.815 – ( - 0.315) = 1.13 V G = -n F e= - 218 KJ/ mol (energy available).Basically, 1 NADH gives 2.2 ATP.ATP has free energy of 30.5 KJ/ mol.30.5 X 2.2 = 67.1 KJ/mol. In other words, of 218 KJ only 67 KJ are captured. This has only 28% efficiency.H are generated by pyruvate dehydrogenase in the matrix of the mitochondria where TCA cycle occurs: glycolysis occurs in cytosol. The inner membrane are tight and ions can not pass through. There is no carrier for H. Basically, H is taken and as the reduced compound and transported across membrane where it is reoxidized to get H back.2 portals:1. Dihydroxy acetone phosphate from glycolysis + NADH, reduced to glycerol 3 phosphate ( imported intoportal) and DHAP ( exported into anti- portal- opposite direction).Electrons are picked up by FAD. Few electrons from FAD than NAD, loss of 1 ATP: equal exchange through2 portals.Oxaloacetate (H carrier ) reduced -- malate (malate alpha keto glutarate- anti portal).Malate reoxidized to oxaloacetate and NAD is H acceptor.There are no carrier for oxaloacetate for the recycle step.Transfer of amino group from GLU acid to oxaloacetate and alpha keto acetate to ASP acid occurs.ASP acid is exported by GLU ASP carrier.ASP---- oxaloacetateAlpha keto glutarate ---- GLU acid.Mitochondria:H in mitochondria.ATP portal – out.NAD portal- in.Mitochondria:There are 2 membranes: outer membrane and inner membrane. There is an intermembrane space between outer and inner membrane.Host of proteins are divided into 4 major complexes:NADH +H  NAD Complex I 1st pumping station.FADH -- FAD Complex II Feeds into system after 1st station.