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Metabolism

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krabi's version from 2015-07-16 23:16

Section

Question Answer
What is the significant of reaction coupling in metabolism?ATP hydrolysis is favourable; phosphate hydrolysis is at 7.3 kcal. Protein polymerization is unfavourable. Free energy changes are cumulative and build on each other
What is the difference between kinetics and thermodynamics?Enzyme is kinetic Influencing rate of reaction e vs. favourability of heat.
Covalent ModificationA regulator group is attached to the protein covalently. For example, kinase can attach a phosphoryl group from ATP to a OG of serine. Another common example is when protein phosphorylases uses inorganic phosphate to activate an enzyme process ie. glycolysis.
Proteolytic CleavageWhen proteins float around in zombie inactive form (zymogen). Is only activated when cleaved by a protease.
Constitutive ActivityPeer pressure, in association with other polypeptides
Allosteric Regulationon/off switch that is reversible. Non-covalent can -/+ catalysis
4 Ways to regulate Enzyme activity(CCPA) Constit. Activity, Covalent modification, Proteolytic cleavage, Allosteric regulation
What is a Feedforward StimulationWhen the enzyme is stimulated by the actual substrate or a molecule.
What is PFK?Phosphofructokinase-1. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it is one of the key regulatory and rate limiting steps of glycolysis.
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Section

Question Answer
What is the difference between CI and NCI?CI binds at active site. In CI can add more substrate and overcome Vmax. Not so in NCI which binds at allosteric/another site and decreases vmax.
allosteric regulation?Reversible on/off switch - allosteric regulation is the regulation of a protein by binding an effector molecule at a site other than the protein's active site.
competitive inhibition?CI - Enzyme Inhibition. Interloper molecules that compete with the substrate for binding at active site.
NCI - Non-competitive Inhibition?enzyme inhibition where the inhibitor reduces the activity of the enzyme and binds equally well to the enzyme whether or not it has already bound the substrate
What is a Protease?Protein cleaving enzymes. w/ active site w/serine β‡’ it’s OH is a nucleophile that attacks the carbonyl carbon in another aa in a peptide chain.
Trypsin, chymotrpsin, elastase? Think protease
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Section

Question Answer
Glycolysis?Converts glucose ==> into pyruvate. Energy released in this process is used to form the high-energy compounds ATP and NADH.
What are the 2 regulatory mechanisms of Glycolysis?1) Hexokinase: Catalyses 1st step in glycolysis & phosphorylation of glucose to G6P, G6P feedback inhibits hexokinase. 2) PFK - subject to allosteric reg. w/ATP Committed step.
Is Glycolysis OIL or RIG?Oxidation
Fermentation? Reduces pyruvate, NAD+ can be reused in glycolytic pathway, (uses pyruvic acid)
Is Fermentation OIL or RIG?Is Reduction.
Name 3 steps of PDC1) Pyruvate is oxidized into CO2 2) Chem rx: oxidatively decarboxylated by PDC β‡’ becomes acetyle attached to Coenzyme A ie. CoA-SH 3) Becomes Acetyl Coa
Is PDC OIL or RIG?Oxidation
What are key proteins in PDC?Carrier - CoEnzyme A, Regulated by AMP or adenosine monophosphate & Prosthetic group - TPP.
What happens during Krebs Cycle or TCA?Mixes the 2 carbon from the Acetyl Carbon w/oxalacetate and releases 2 CO2, NADH & FADH2
What are the carriers in Krebs?Electron carriers NADH & FADH2 generates ATP in ETC
What chemical rx during Krebs?3 carboxylic acids are decarboxylated
Is ETC - OIL or RIG?Oxidation
What 3 steps happens during ETC?1) Reoxidize all electron carriers in previous steps 2) Store energy in ATP currency 3) Pump H protons back
Name 6 proteins in ETCNADH Dehydrogenase, Q, Cyto.C. Reductase, Cyto.C, C, ATPSynthase
What is the chem rx during ETC?Coupled reactions ATP production + proton gradient
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Section

Question Answer
HexokinaseCatalyses 1st step in glycolysis & phosphorylation of glucose to G6P, G6P feedback inhibists hexokinase.
What is a prosthetic group?Non protein molecule covalently bounded to active site of the enzyme. For example, the TPP in PDC.
What is a NAD?Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells. The compound is a dinucleotide β‡’ joined through their phosphate groups.
What is the function of NAD?NAD is involved in redox reactions, carrying electrons from one reaction to another.
Glycogenolysis?is the breakdown of glycogen to glucose-1-phosphate and glycogen. Glycogen branches are catabolized by the sequential removal of glucose monomers.
Gluconeogenesis (GNG)?A metabolic pathway that results in creation of glucose (from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol)
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