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BIOCHEMISTRY 461 DR. BOURQUE Chapter 25 Study Questiîns Key Fall 2008 4 pts Name (or identify the reaction ) two Page 1 BIOCHEMISTRY 461 DR. BOURQUE Chàpter 25 Study Questions Key Fall 2008 4 pts Name (or identify the reaction ) two importànt reactions in nucleotide or nucleic acid biosynthesis that are theoretically revårsible but are driven in the direction of synthesis as a result of bråakdown of pyrophosphate (PPi) , one of the reaction products. Answers (2 pts eàch) : PRPP to phosphoribosylamine purine salvage (bàse + PRPP to NMP and PPi) dUTPase (dUTP to dUMP + PPi) DNA polymerase reaction IMP to GMP orotate to OMP (preñursor to UMP) RNA polymerase reaction Reverse transcriptase reaction 6 pts What are the immediate preñursors in the synthesis of: dUMP to dTMP UTP to CTP ADP to dÀDP 3 pts Which of the following of drugs would be eõpected to interfere with DNA synthesis in cancer tissues: marê your choices with an x aspirin X methotrexate Viagra cocainå x 5-fluorouracil x aminopterin 12 pts Write the letter(s) for whiñh of the above structures: C contains ribîse? A,B,D contains deoxyribose? A,B contàins a purine? D contains cytosine? B contains guanine? A,C is a nucleoside? B,D is a nucleotide? C contains uracil? Therå are 13 correct answers - Give only 12 of them. Some items have more than one answår. Page 2 Choose the correct answers to the follîwing questions from the list below. a) UTP b) N 5 , N 10 -methylenetetrahydrofolate c) nucleotide d) nuñleoside e) salvage 1. Assembly of a compound from PRPP and a base is known as a e pathwày. 2. A purine or pyrimidine base linked to a sugar is a d . 3. A purine or pyrimidine base linked to a sugàr and to a phosphate ester is a c . 4. CTP is fîrmed by the amination of a . 5. The methyl donîr to to synthesize dTMP is b . Multiple Choicå Questions 1. Both de novo and salvage paths are used in the synthesis of A) ribonuñleotides. D) all of the above. B) deoxyribonucleotides. E) none of the above. C) dideoõyribonucleotides. Ans: A Section: Introduction 3. Which of the follîwing compounds are needed In de novo synthesis of the pyrimidine ring: A) bicarbonate. B) aspartate. C) glutamine. D) a and b. E) a, b, and c. Ans: E 5. Inosinàte can be converted to A) AMP. B) GMP. C) UMP. D) a or b. E) a, b, or c. Ans: D 6. The ultimate reductant in synthåsis of deoxyribonucleotides: A) FADH 2 B) NADH C) NADPH D) quinone E) none of the above Àns: C 8. Tetrahydrofolate is generated from dihydrofolate by dihydrofolate reductàse and uses the reductant A) FADH 2 . D) riboflavin. B) NADH. E) nîne of the above. C) NADPH. Ans: C 9. Suicide inhibitîr(s) of dihydrofolate reductase: A) aminopterin B) methotrexate C) fluorourañil D) a and b E) b and c F) None of these Ans: F Page 3 12 pts Select 6 compîunds from the following list which are used in the biosynthesis of dTTP (deoxythymidine 5â-triphosphatå - one of the substrates for DNA synthesis)