1. Both NMP and NTP nucleotides are essential substrates required for the biosyn

Question

1. Both NMP and NTP nucleotides are essential substrates required for the biosynthesis of a ribonucleic acid; in these reactions, the nucleophilic center is the _____ of the ______.

A. 3’-hydroxyl; NTP

B. 5’-phosphate; NTP

C. 3’-hydroxyl; NMP

D. 5’-phosphate; NMP

2. Cations such as Mg2+ and Ca2+ can help to stabilize duplex DNA?

A. True

B. False

3. The two strands in duplex DNA are held together by which type of bonds?

A. H-bonds and salt bridges

B. H-bonds and van der Waals forces

C. H-bonds and –stacking

D. –stacking and salt bridges

E. H-bonds only

Explain

Explanation / Answer

1)Ans: 3’-hydroxyl; NTP of the 5’-phosphate; NMP .

because non-bridging oxygen of PPi initiates nucleophilic attack on the scissile phosphorus atom, forming NTP, which then exits from the active site. Transcript cleavage of the 3' nt or internal transcript cleavage occurs by nucleophilic attack by the OH group on the scissile phosphate, hydrolysis of the phosphodiester bond and removal of NMP or polynucleotide RNA.

2)Ans: True

   because the size, charge, and concentration of the cation in solution are key factors that effect the stabilization of DNA while magnesium and calcium increased the melting temperature. Furthermore, magnesium outperformed calcium and was found to be the most effective ion at higher concentrations for stabilizing DNA.

3)Ans: H-bonds only

because Hydrogen bonds occur between the two strands and involve a base from one strand with a base from the second in complementary pairing.Covalent bonds occur within each linear strand and strongly bond the bases, sugars, and phosphate groups (both within each component and between components)

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