Cell Biology Quiz 6 - quiz answer key is given PDF

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Practice questions 6 1. If a reaction is calculated to have a +ΔG, can it ever occur? A. No, because it is thermodynamically impossible B. No, because reactions can only have a –ΔG. No reactions can have a +ΔG if they are written properly C. Yes, if they are energetically coupled with another reaction that has a sufficiently negative ΔG D. Yes, but only if the ΔH is equal to the enthalpy E. No, because it would require creation of new energy and that is prohibited by the first law of thermodynamics 2. Which of the following is the best way to increase the cAMP in a cell? A. Stimulate an ionotropic receptor B. Decrease adenylate cyclase activity C. Decrease phosphodiesterase activity D. Lower ATP concentrations E. Increase protein kinase activity 3. Which of the following would be least likely to happen if a protein was phosphorylated? A. The net charge would become more positive at pH=7.0 B. The conformation could change C. It could detach from something that was held to it by ionic bonds D. It could become more water soluble E. It could decrease its binding to DNA 4. What are mutations? A. Deleterious changes in amino acid composition that lead to diminished activity of a protein but not increased activity B. Conformational changes in a protein that always lead to death of the cell C. The DNA sequences seen in normal proto-oncogenes D. A change in the DNA sequence of a gene that persists as the DNA replicates E. A change in DNA that only happens in cancer genes 5. Which of the following is not an energy source for doing useful work in a cell? A. ATP B. Entropy C. Ion gradients D. Light

6. Which of the following statements is true? A. The total amount of free energy added to the system is +ΔH B. Enthalpy is the total amount of useful energy in a system C. The energy released from the system that can be used to do work is –ΔG D. In an exergonic reaction, the free energy of the system must be positive

7. Which of the following is most likely to happen if a codon was changed from UAU to UAG? A. Nothing, it would still have the same amino acid sequence because this was only a change in one nucleotide B. The protein would be shorter C. Overall charge on the protein (at pH=7.0) would change D. It would bind less tRNA 8. Which is of the following is true? A. Some enzymes can change ΔG B. Enzymes can lower the activation energy (Ea) of a reaction C. An increase in the concentration of substrates will always increase the rate of the reaction D. Both Km and Vmax are determined from a plot with Rate of the Reaction on the Y-axis and Time on the X-axis...