What structural features are shared by spliceosomes(Figures 8-16 and 8-17) and ribosomes? Why are bothstructures used to support the RNA World theory?

How can the 4 nucleotides present in DNA code for the 20 different amino acids found in proteins? How many bases would be needed in a codon if there were five RNA bases instead of four?

Why does RNA form A-form helices and not B-form?

Discuss the following: “During the evolution of life on earth, RNA lost its glorious position as the first self- replicating catalyst. its role now is as a mere messenger in the information flow from DNA to protein.”

Which of the molecules of RNA is the most likely to fold into a specific structure as a result of intramolecular (within itself) base-pairing?  Explain. 5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′ 5′-UGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUG-3′ 5′-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-3′ 5′-GGAAAAGGAGAUGGGCAAGGGGAAAAGGAGAUGGGCAAGG-3′

What feature of RNA would allow it to function as a ribozyme? Why are there no naturally occurring DNA enzymes?

One remarkable feature of the genetic code is that amino acids with similar chemical properties often have similar codons. thus codons with U or C as the second nucleotide tend to specify hydrophobic amino acids. Can you suggest a possible explanation for this phenomenon in terms of the early evolution of the protein-synthesis machinery?

What are the key properties of the genetic code? Given that the genomes of all organisms are made up of As, Ts, Cs, and Gs, how does one account for diversity in organisms? What are some factors that could adversely affect diversity in nature?

Why does the sequence ITLIIFGVIAGVIGTILLI more likely to contain a membrane-spanning sequence?