Question

4. The basie differences between RNA and DNA are a. the organic bases only b. bases, ribose uaits, and the phosphodiester linkage c. bases, ribose units, and the glycosidic bond type bases and the ribose units oaly 5. The solubility characteristics of the pyrimidine or purine bases and the corresponding nucleosides differ greatly. Which of the following statements is not true? a. purine bases are quite soluble in water b, nucleosides are much more soluble than the corresponding bases c. nucleosides and nucleotides are quite soluble in water d. ribose units are very soluble in water 6. Adenosine and guanosine are found predominantly in which tautomeric forms, respectively? b. imino & keto, respectively a. amino & keto, respectively c. amino& enol, respectively.imino & enol, respectively 7. Consider a purine base with the pKa values for the conjugate acid forms of . The N-I, N-3, and N-7 atoms have pKas equal to Which statement is correct about this the various ring nitrogens. 4.0, 8.2, and 7.0, respectively. molecule at pH 7 a. the three nitrogens are protonated at pH 7 b, N-1 is deprotonated, N-3 is protonated and N-7 is 50% protonated c. N-1 is protonated, N-3 and N-7 are deprotonated d. N-1 and N-7 are deprotonated, while N-3 is protonated 8· The component(s) of DNA which is responsible for the absorbance band at 250-270 nm is a. bases, pentoses, and phosphates all contribute b. only bases c. only bases and pentoses d. only pentoses and phosphates 9. AMP has three relevant ionizable groups. N1 of adenine has pKa 4.0 and the phosphomonoester has pKas at 1.0 and 6.0. The net charge on AMP at pH 7.0 is approximately d. 0 10. The thermodynamically most favorable form for pyrimidine nucleotides is a. syn conformation c. both are equally favored b. anti conformation d. cannot be predicted. II. Which molecule contains an acid anhydride bond? .AMP .ATP 12. All the NTPs are essential for RNA ynthesis but OTP i, also aestal in b. glycogen biosynthesis a.protein biosynthesis fatty acid biosynthesis thesis d. 13. Indicate which of the following does not oceur for atoms in the sugar pucker which occurs in a furanose in the 3 exo configuration. a, C-2" and the base are on the same side of the -ribose plane b.С.3' is on the same side ofthe-ribose plane, as the C-5, c. the C-1, the O and the C-4 atoms are part of the "ribose plane d. C-2 and the C-5 are on the same side of the "ribose plane" 14. In duplex DNA, what group on the molecule below is the hydrogen bond donor to the thymine base? b. N-1 on the base d. hydroxyl on C3 of ribose a. N-7 on base c. amine on C-6 of base 15. The term glycoconjugates is used to describe b. glycoproteins d. both glycolipids and glycoproteins a. glycolipids e. carbohydrates 16. A glycosidic bond is the linkage formed between a. an acid and an alcohol c. a hemiacetal and an alcohold. an acetal and an alcohol b. two alcohols 17. Indicate the number of possible stereoisomers for a linear aldopentose. c. 12 d. 16 18. How many enantiomeric pairs are found for a linear aldohexose? d. 16 19. Which carbon on glucose determines whether it is the D- or L-stereoisomer? Carbon 1 is the carbonyl carbon. b. 4 d. 6

Answer 1

The basic ai-tHerences behdean RNA & DNA are e bases ana the ri bose Units on ine n teams Corsect anwer is (d