The A260/A280 ratio of a double-stranded DNA sample can be used to assess its purity. The value for the pure DNA is ----------------

#Question id: 281

#Unit 1. Molecules and their Interaction Relevant to Biology

Histones associate with DNA primarily through ________.

#Question id: 12292

#Unit 10. Ecological Principles

#Question id: 4456

#Unit 3. Fundamental Processes

Correct statement about two striking structural changes are seen in the enzyme upon isomerization from the closed to the open complex;

A. First, the pincers at the front of the enzyme clamp down tightly on the downstream DNA.

B. Second, there is a major shift in the position of the amino-terminal region of s. When not bound to DNA, s region 3.2 lies within the active center cleft of the holoenzyme, blocking the path that, in the open complex, is followed by the template DNA strand.

C. In the open complex, region 1.1 shifts some 50 A˚ and is now found on the outside of the enzyme, allowing the DNA access to the cleft.

D. Region 1.1 of s is highly negatively charged ( just like DNA).

#Question id: 9271

#Unit 6. System Physiology – Plant

#Question id: 28625

#Unit 2. Cellular Organization