Metabolism- Quiz 4 Questions And Answers With Complete Solutions

Porphyrin correct answer: Cyclic molecules formed by the linkage of 4 pyrole rings through methynl bridges. They bind metals tightly Name the 4 physiological roles of the HEME porphoryin correct answer: 1. Mitochondrial cytochrome: generate H+ gradient in ETC 2. Hemoglobin and Myoglobin: O2 transport in blood and muscle 3. Cytochrome P450 enzymes: metabolize fat soluble compounds. (CYP3A4) important in drug reactions 4. Catalase: antioxidant enzyme hydrolyzes H2O2 Where is Heme made? correct answer: Primarily by Liver and Bone marrow isoforms with many enzymes ALA synthase correct answer: Catalyzed the condensation of glycine and succinyl CoA to form aminolevulinic acid (ALA) in an irreversible reaction The transcription of ALA synthase is inhibited by? correct answer: Hemin- the oxidized form of heme Glucose ALA dehydrogenase correct answer: condenses 2 molecules of ALA to form pyrole compound porphobilinogen (PBG) Hydroxymethylbilane synthase correct answer: Condenses 4 molecules of PBG to form hydroxymethylbilane What are the 2 rate limiting steps in the synthesis of Heme? correct answer: 1. ALA synthase 2. Hydroxymethylbilane synthase Uroporphorynogen synthase correct answer: Catalyzes ring closure of hydroxymethylbilane to form uroporphoryinogen I Uroporphorynogen III cosynthase correct answer: Isomerizes D ring side chains of uroporphorynogen I to form uroporphorynogen III Uroporphorynogen III is the common precursor for... correct answer: chlorophyll, cobalmine, and heme