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TLS Online TPP Program

#Question id: 2884

When the temperature of a solution of DNA is raised to near the boiling point of water, the optical density, (called absorbance) at 260 nm markedly increases, a phenomenon known as hyperchromicity. Which of the following statement is INCORRECT from the given set of statements?

#Unit 2. Cellular Organization

  1. The explanation for this increase is that duplex DNA absorbs more ultraviolet light by ~40% than do individual DNA chains.

  2. This hyperchromicity is due to base stacking, which increases the capacity of the bases in duplex DNA to absorb ultraviolet light.

  3. The sharpness of the increase in absorbance at the melting temperature tells us that the denaturation and renaturation of complementary DNA strands is a highly cooperative, zippering-like process.

  4. At high ionic strength, the negative charges are shielded by cations, thereby destabilizing the helix. Conversely, at low ionic strength, the unshielded negative charges render the helix more stable.

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TLS Online TPP Program

#Question id: 15168

#Unit 2. Cellular Organization

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TLS Online TPP Program

#Question id: 11499

#Unit 9. Diversity of Life Forms

Biologists have long been aware that the defunct kingdom Protista is paraphyletic. Which of these statements is both true and consistent with this conclusion?
TLS Online TPP Program

#Question id: 32211

#Unit 1. Molecules and their Interaction Relevant to Biology

Identify the structure shown

 
TLS Online TPP Program

#Question id: 32250

#Unit 2. Cellular Organization

All the Golgi glycosidases and glycosyl transferases are:
TLS Online TPP Program

#Question id: 13049

#Unit 13. Methods in Biology

What is the role of goat anti-rabbit IgG horseradish peroxidase conjugate in the experiment?