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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: 443

#Unit 1. Molecules and their Interaction Relevant to Biology

The free energy for ATP hydrolysis in vivo is actually greater than the standard free energy change of -30 kJ mol-1 because
TLS Online TPP Program

#Question id: 444

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is not a factor contributing to the large free energy of hydrolysis of ATP?
TLS Online TPP Program

#Question id: 445

#Unit 1. Molecules and their Interaction Relevant to Biology

In order for a reaction to proceed spontaneously from left to right as written
TLS Online TPP Program

#Question id: 446

#Unit 1. Molecules and their Interaction Relevant to Biology

Which statement is false about ATP?
TLS Online TPP Program

#Question id: 447

#Unit 1. Molecules and their Interaction Relevant to Biology

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (DG'°) of 23.8 kJ/mol.  Under what conditions encountered in a normal cell will the free-energy change (DG) be negative, enabling the reaction to proceed spontaneously to the right?
TLS Online TPP Program

#Question id: 448

#Unit 1. Molecules and their Interaction Relevant to Biology

During glycolysis, glucose 1-phosphate is converted to fructose 6-phosphate in two successive reactions: Glucose 1-phosphate -> glucose 6-phosphate DG'° = –7.1 kJ/mol Glucose 6-phosphate -> fructose 6-phosphate DG'° = +1.7 kJ/mol DG'° for the overall reaction is: