Put the steps of the process of signal transduction in the order they occur.

1. A conformational change in the signal-receptor complex activates an enzyme.

2. Protein kinases are activated.

3. A signal molecule binds to a receptor.

4. Target proteins are phosphorylated.

5. Second messenger molecules are released.

#Question id: 398

#Unit 1. Molecules and their Interaction Relevant to Biology

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). (See figure.)

If the pH of blood drops, one would expect ________.

#Question id: 399

#Unit 1. Molecules and their Interaction Relevant to Biology

Calculate the pH of a 1 L solution containing 0.100 M formic acid and 0.100 M sodium formate before and after the addition of 1.00 mL of 5.00 M NaOH. How much would the pH change if the NaOH were added to 1.00 L of pure water? (pKa for formic acid is 3.75)

#Question id: 400

#Unit 1. Molecules and their Interaction Relevant to Biology

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that ________.

#Question id: 401

#Unit 1. Molecules and their Interaction Relevant to Biology

.Which of the following graphs describes the relationship between [H3O+] and pH?

#Question id: 402

#Unit 1. Molecules and their Interaction Relevant to Biology

If the DG'° of the reaction A -> B is –40 kJ/mol, under standard conditions the reaction:

#Question id: 403

#Unit 1. Molecules and their Interaction Relevant to Biology

For the reaction A -> B, DG'° = –60 kJ/mol.  The reaction is started with 10 mmol of A; no B is initially present.  After 24 hours, analysis reveals the presence of 2 mmol of B, 8 mmol of A. Which is the most likely explanation?