Exam 4: Nucleic Acids and the Rna World

What forms the "backbone" of a nucleic acid?

Which one of the following is not a way that RNA is seen as intermediate between DNA and proteins?

The "information system" of the cell involves stable genetic information being stored as , which can be used to make a "disposable" relatively short- lived) copy of this information as .

What is the structural feature that allows DNA to replicate?

Nucleic acids have a definite polarity, or directionality. Stated another way, one end of the molecule is different from the other end. How are these ends described?

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. -In the acid- base reaction described in the preceding paragraph, a proton H+) is being transferred. What is acting as the proton acceptor?

In the secondary structure of DNA, the a- helical twists are organized into

Which of the following best describes DNA's secondary structure?

What is the difference between a ribonucleotide and a deoxyribonucleotide?

Nucleic acids are polymers made up of which of the following monomers?

The work of Bartel's group on the ribozyme RNA replicase supports which conclusion?

Why is DNA said to be antiparallel?

Bartel's research group showed that an RNA replicase ribozyme could be created by

If a molecule of DNA contains 10% cytosine, it has guanine and adenine respectively.

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. -If the cytosine is positively charged +) before self- cleavage, what would its charge be after self- cleavage?

A nucleotide is made up of which of the following subunits?

Which of the following nitrogenous bases are purines?

Although DNA is the main hereditary material in all life- forms, it lacks one important characteristic to make it a candidate for the first life- form. Why have researchers rejected the idea that DNA was found in the first Life- form?

Which of the following nitrogenous bases is found in RNA, but not DNA?

Hairpins and stem- and- loop patterns make up what part of RNA's structure?