Practice Problems on Nucleic Acids

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Debra Gray
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1 A.1 ractice roblems on ucleic Acids 1. Which one of the following structures is not a purine? 2 A B Which one of the following is not a pyrimidine? 2 A 3 B S Br 2

2 A.2 3. ow many of the following molecules are classified as pyrimidines? Which one of the following structures is not a tautomer of adenine? A B 5. Which one of the following structures is not a tautomer of guanine? 2 2 2

3 A.3 6. Which one of the following structures is a naturally occurring nucleotide? A 3 B 2 S omplete and total hydrolysis of RA yields which one of the following mixtures? A) A mixture of oligoribonucleotides B) A mixture of ribonucleotides and phosphate ) A mixture of ribonucleosides and phosphate ) A mixture of ribonucleosides and nucleobases ) A mixture of -ribose, nucleobases, and phosphate

4 A.4 8. Which one of the following statements is correct? A) A is the only genetic material, RA is not B) A and RA are both polymers of nucleosides ) A and RA both contain adenine and guanine as pyrimidine nitrogenous hetereocycles ) nly RA uses the thymine nucleobase ) The term nucleic acids refers to the acidic nature of the phosphodiester. 9. Which one of the following structures is a nucleoside? A 2 B Which one of the following is T an advantage of the dye-terminator method of A sequencing over the 32 -ddt method? A) o A polymerase is required B) o radioactive nucleotides are required ) The products of the sequencing reaction can be separated by capillary electrophoresis and detected by fluorescence ) All four dye-labelled ddts can be present in the reaction mixture ) nly one strand of A is required

5 A Which one of the following statements is incorrect? A) A and RA are polymers that are composed of nucleosides joined by phosphodiester groups that link the 5 - of one nucleoside to the 2 - of the next nucleoside. B) omplete hydrolysis of A may yield thymine but cannot yield uracil ) omplete hydrolysis of RA will yield some --ribofuranose ) The -glycoside bond in nucleotides is in the configuration ) pair interactions are the result of specific hydrogen bonding between nucleobases, and (A and T) constitutes one such pair 12. A strand of A was sequenced using 32 -labelled ddts and the primer 5 -TA-3. d on the resulting gel below, what is the sequence of the original strand? (The identity of the ddt is indicated at the top of each lane). A) 3 -ATGATGTAGTA-5 B) 3 -ATGTAGTA-5 ) 3 -TATAATGGAT-5 ) 3 -ATGATGATGTA-5 ) 3 -ATGATGTA-5 A G T 13. In the laboratory synthesis of A, why is a dimethyoxytrityl protecting group used instead of a trimethoxytrityl or a monomethoxytrityl?

6 A What are the reagents (1 3) used for nucleic acid synthesis? MT 1 MT 2 MT MT Which of the following statements are true regarding both Merrifield peptide synthesis and nucleic acid synthesis? ircle all that apply. The syntheses are usually done using solution-phase chemistry due to its ease Both methods use an insoluble polymeric material that serves the function of at least one protecting group The last step of deprotection and cleavage from the support is done with a strong acid The tert-butyloxycarbonyl group is used to block the -amino group in polypeptide synthesis and the 5 - group in nucleic acid synthesis Both dicyclohexylcarbodiimide and tetrazole are dehydrating agents

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