Exam 4: Nucleic Acids and the Rna World

By convention, the sequence of bases in a nucleic acid is always written in which direction?

Use the following information when answering the corresponding questions). Shuichi Nakano reported in Science in February 2000 that, "The RNA enzyme ribozyme) from hepatitis delta virus catalyzes self- cleavage of a . . . [chemical] . . . bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme. The author goes on to show that this self- cleavage is made faster by joining it with an acid- base reaction that neutralizes the negative charge. Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid, and magnesium hydroxide acting as the base. Specifically, the cytosine donates its proton H+) to neutralize the unstable negative charge that would have formed on the ribozyme. -Is Nakano's quote consistent with the textbook's claim that RNA is a good candidate for the first life- form?

What feature of mononucleotides provides the energy needed for polymerization when nucleic acids are formed?

What is responsible for holding the two strands together in the DNA double helix?

Which of the following includes all of the pyrimidines found in RNA and/or DNA?

Which of the following statements best summarizes the differences between DNA and RNA?

What is the difference if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence

Which of the following is not a difference between RNA and DNA?

Which of these scientists was not directly involved in the discovery of DNA's structure?

Why is DNA more appropriate than RNA as the information storing molecule of the cell?

The term ribozyme describes what property of RNA molecules?

In the context of chemical evolution, DNA's structure is interesting because it suggests a possible copying mechanism. What about DNA's structure facilitates copying?

Use the following information when answering the corresponding questions). Shuichi Nakano reported in Science in February 2000 that, "The RNA enzyme ribozyme) from hepatitis delta virus catalyzes self- cleavage of a . . . [chemical] . . . bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme. The author goes on to show that this self- cleavage is made faster by joining it with an acid- base reaction that neutralizes the negative charge. Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid, and magnesium hydroxide acting as the base. Specifically, the cytosine donates its proton H+) to neutralize the unstable negative charge that would have formed on the ribozyme. -What can be inferred about the free- energy profile for the self- cleavage reaction from the information provided in the paragraph?

Use the following information when answering the corresponding questions). Shuichi Nakano reported in Science in February 2000 that, "The RNA enzyme ribozyme) from hepatitis delta virus catalyzes self- cleavage of a . . . [chemical] . . . bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme. The author goes on to show that this self- cleavage is made faster by joining it with an acid- base reaction that neutralizes the negative charge. Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid, and magnesium hydroxide acting as the base. Specifically, the cytosine donates its proton H+) to neutralize the unstable negative charge that would have formed on the ribozyme. -Which of the following chemical bonds do you think Nakano is referring to in his quote?

Which of the following statements about the 5' end of a polynucleotide strand of RNA is correct?

Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA?

If DNA is heated to 95°C, the bonds between complementary strands break, resulting in two single strands of DNA. In this process, which bases will separate first because they have less hydrogen bonds between them?

Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X- rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?

Why do many researchers consider RNA to be the best candidate for the first life- form?