Consider following statements for catalytic mechanism of RNA polymerase

A. RNA synthesis by RNA polymerase. The reaction involves two Mg2+ ions, coordinated to the phosphate groups of the incoming nucleoside triphosphates (NTPs)

B. Three Asp residues, which are highly conserved in the RNA polymerases of all species. One Mg2+ ion facilitates attack by the 39-hydroxyl group on the phosphate of the NTP; the other Mg2+ ion facilitates displacement of the pyrophosphate, and both metal ions stabilize the pentacovalent transition state.

C. About 17 bp of DNA are unwound at any given time. RNA polymerase and the transcription bubble move from left to right along the DNA as shown, facilitating RNA synthesis. Movement of an RNA polymerase along DNA tends to create negative supercoils (overwound DNA) ahead of the transcription bubble and positive supercoils (underwound DNA) behind it.

D. The RNA polymerase is in close contact with the DNA ahead of the transcription bubble as well as with the separated DNA strands and the RNA within and immediately behind the bubble. A channel in the protein funnels new NTPs to the polymerase active site. The polymerase footprint encompasses about 35 bp of DNA during elongation.

#Question id: 395

#Unit 1. Molecules and their Interaction Relevant to Biology

How would acidification of seawater affect marine organisms? Acidification of seawater would ________.

#Question id: 394

#Unit 1. Molecules and their Interaction Relevant to Biology

What will be the H+ ion concentration in a solution prepared by mixing 50.0 mL of 0.20 M NaCl, 25 mL of 0.10M NaOH and 25.0 mL of 0.30M HCl?

#Question id: 392

#Unit 1. Molecules and their Interaction Relevant to Biology

When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?

#Question id: 388

#Unit 1. Molecules and their Interaction Relevant to Biology

Calculate the pH of a solution prepared by mixing 2.0 mL of a strong acid solution of pH=3.0 and 3.0 mL of a strong base of pH=10.0.

#Question id: 386

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following properties of water does not contribute to the fitness of the aqueous environment for living organisms?

#Question id: 385

#Unit 1. Molecules and their Interaction Relevant to Biology

In which reaction below does water not participate as a reactant (rather than as a product)?