Give correct explanation, why RNA polymerase can initiate a new RNA chain on a DNA template without any primer?

A. Because RNA polymerase starts most transcripts with an A, and that ribonucleotide binds the template nucleotide (T) with only two hydrogen bonds.

B. The enzyme has to make specific interactions with one or all of the DNA template strand, the initiating ribonucleotide, and the second ribonucleotide—holding one (or all) rigidly in the correct orientation to allow chemical attack on the incoming NTP.

C. The structure of the open complex shows that the s region 3/4 linker interacts with the template strand, organizing it in the correct conformation and location to allow initiation.

D. Consistent with this, in experiments using an RNA polymerase containing a s70 derivative lacking this part of s, initiation requires much lower than normal concentrations of one or both of the first two ribonucleotides.

#Question id: 387

#Unit 1. Molecules and their Interaction Relevant to Biology

For a weak acid with a pKa of 6.0, What would be the ratio of acid to salt at pH 5.

#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: 389

#Unit 1. Molecules and their Interaction Relevant to Biology

A weak acid HA has a pKa of 5.0.  If 1.0 mol of this acid and 0.1 mol of NaOH were dissolved in one liter of water, what would the final pH be?

#Question id: 390

#Unit 1. Molecules and their Interaction Relevant to Biology

What are the properties arising due to varying concentrations of solute in a given solvent, irrespective of the nature of solute with respect to the solvent?

#Question id: 391

#Unit 1. Molecules and their Interaction Relevant to Biology

In a hospital laboratory, a 10.0 mL sample of gastric juice, obtained several hours after a meal, was titrated with 0.1 M NaOH to neutrality; 7.2 mL of NaOH was required. The patient’s stomach contained no ingested food or drink, thus assume that no buffers were present. What was the pH of the gastric juice?

#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)?