BCH 119S Midterm: Unit 4 Review

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University of Texas at Austin
BCH 119S

4/11/17 Lipid metabolism - Triacylglycerols  storage of fats (fatty acids attached to a glycerol) - Fatty acids are broken into 2C and 3C intermediates that feed into the citric acid cycle Fatty acid catabolism (beta oxidation) Steps of beta oxidation - start with fatty acid chain and oxidize it - remove an acetyl group on remaining acetyl group o oxidize to produce C=C bond between C2 and C3 o add water across bond (need an O atom) - Step 3  oxidize again and generate NADH - Step 4  hydrolize to remove acetyle coA (now need to add new CoA)  thiolysis - Repeat until chain completely degraded to acetylcoA units Beta exidation feeds electrons to ETS and generates ATP by ox-phos - spiral pathway for a C26 carbon  7 rounds EVEN CHAIN Net products of each round  less QH2 because it would skip complex I to make less ATP - each acetyl coA  10 ATP - total ATP yield  14 ATP - total ATP yield = (n/2 -1)X14 +10 -2 ODD CHAIN gets to last step but you have 3 carbons left  propionyl-coA (3-C frag) - convert propionyl-coA into methylmaloyl-coA - takes 8 steps to make acetyl coA - carboxylase adds CO2 to C2 - costs 1 ATP oxidation takes place in mitochondrial matrix (also TCA) Total ATP =[ C16/2 -1] X 14 + (10-2) = 106 Beta oxidation in mitochondrial matrix Synthesis  cytoplasm Fatty Acid doesn’t generate NADH or QH2  it’s anabolic so it uses NADPH 1 Acetyl CoA added uses 1 ATP 1) biotin is carboxylated 2) Carboxyl group is transferred to acetyl-CoA to make malonyl coA  costs 1 ATP 3) Acetyl coA load onto Cys residue, 4/13 Final exam  all old exams exactly Part II  just ch 3, 20-22 Cholesterol Synthesis - cholesterol also built from acetyl units st - 1 steps similar to ketogenesis - ketone bodies synthesized in mitochondria; cholesterol in cytosol - diverge after formation of HMG-CoA (point of regulation) - conversion to melalonate, then isopentenyl pyrophosphate, then squalene - It takes 21 reactions to convert squalene to cholesterol (30+ to make cholesterol) - Most cholesterol packaged into VLDL o Precursor for other hormones  testosterone and estrogen o Precursor of bile acids like cholate ▪ Cholate synthesized in liver and stored in gallbladder, secreted into small intestine ▪ Only route of exit - Cholesterol transport  LDL o Lipoprotein degraded inside the cell and cholesterol released o HDL removes extra cholesterol and takes it back to liver for reprocessing o Can also bind to repression of gene for LDL receptor o Feedback inhibition Nitrogen - most oxidation states - form we use is ammonia  Pk is always NH4+ - fixing nitrogen o biologically o by microbes o catalyzed by nitrogenase ▪ metalloprotein FE-S clusters and Fe-Mo cofactor ▪ costs 16 ATP ▪ sensitive to oxygen, so usually anaerobes and can compartmentalize - Nitrogen cycle Just know the precursors and intermediates Amino acid catabolism - fuel for certain organs and tissues Classification of amino acids Is it acetyle-CoA or an intermediate in ketogenesis? - yes then it’s ketogenic - no- then it must be glucogenic Ketogenic diet  - insulin resistance varies  can reverse it - insulin is a fuel storage hormone  lower insulin levels o carbs really increase insulin o then protein o fat  o less insulin production  saturated fats o ketoacidosis  need all 3 macronutrients ▪ LCHF - Brown fat  higher mitrochondria  fewer Atp synthase o Proton translocators o Makes less than ATP o Good because you lose a lot of energy as heat o Where is brown fat  look that up! o Uncoupling = gradient without ATP synthase Module Nucleotide Synthesis 4/18 - AMP and GMP are derived from the purine nucleotide IMP - Pyrimidine nucleotide synthesis produces UTP then CTP - Nucleotides can be recycled from nucleic acids and cofactors that are broken down o Can also be synthesized de novo from several amino acids - Purine synthesis o AMP and GMP o PRPP (the sugar) is made first  ribose biphosphate  5- phosphoribosyl o 10 steps  requires Gln, Gly, Asp, and HCO3- and HC=O from tetrahydrofolate (1C carrier) o product = IMP ▪ base = hypoxanthine ▪ for AMP we need NH2 from Asp ▪ Fr GMP we need NH2 from Gln ▪ Kinases add P groups o High GTP = high AMP o High ATP = high GMP o High levels of one purine = upregulation of other purine formation - Pyrimidine synthesis o Base built first, then attached to PRPP o Requires Gln, Asp, HCO3- o Produces UMP o Simpler so requires fewer amino acids o UMP need NH from glutamine, double bon from aspartate, o Kinases then convert UMP to UDP and UTP o CTP synthetase makes CTPP from UTP o Regulation ▪ Feedback inhibition by UMP, UDP, UP ▪ ATP activates 1 step in synthesis • Balances levels of purines and pyrimidines • ATP is a purine  activates pyrimidine formation - How to synthesize deoxyribonucleotides - Integration of fuel metabolism o Various organs are specialized for fuel storage, mobilization, and other functions o Metabolites travel between tissues in interorgan metabolic pathways o Regulation through compartmentation ▪ Compartmentaiton keeps processes spatially spate ▪ Hormonal control uses outsides signal to stimulate change inside cell o Opposing processes always regulatied ▪ Eg beta oxidation in mitochondrial matrix vsfatty acid synthesis in cytosol ▪ Requires membrane transporters - Liver: fed state o Glucose stored as glycogen o Excess glucose and amino acids changed to acetyl coA o Acetyl CoA used to synthesize fatty acids ▪ Converted to triacylglycerols and sent to other tissues - Liver: fasted state o Breaks down glycogen to glucose  sends to other tissues o TAGS broken down to acetyl-coA can be used to make ketone bodies o Amino acids can be broken down and converted - Lever fed or fasted o Always processes lactat
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