According to the RNA world model, a ribozyme would replicate by creating a double-stranded RNA intermediate. Would you expect the intermediate to have the same catalytic activity as the original ribozyme? Justify your answer with an explanation.

If nucleotides from the DNA of a human were quantified and 30 percent of them contained the base adenine, what percentage of them would contain the base guanine? a. 20 percent b. 30 percent c. 40 percent d. 70 percent

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA? a. 5′-AGCT-3′ with 5′-TCGA-3′ b. 5′-GCGC-3′ with 5′-TATA-3′ c. 5′-ATGC-3′ with 5′-GCAT-3′ d. All of these pairs are correct.

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture a. DNA. b. proteins. c. cellulose. d. sucrose.

What would be the sequence of the strand of DNA that is made from the following template: 5′-GATATCGAT-3′? (Your answer must be written 5'→3'.) How would the sequence be different if RNA were made from this DNA template?

Make a concept map (see BioSkills 12) that relates DNA's primary structure to its secondary structure. Your diagram should include deoxyribonucleotides, base-stacking interactions, purines, pyrimidines, phosphodiester linkages, DNA's primary structure, DNA's secondary structure, complementary base pairing, and antiparallel double helix.

RNA and DNA are similar because . a. both are double-stranded helices; b. uracil is found in both of them; c. both contain the sugar deoxyribose; d. both are made up of nucleotides consisting of a sugar, a phosphate, and a base

DRAW IT Copy the polynucleotide strand in Figure 5.23a and label the bases G, T, C, and T, starting from the 5′ end. Assuming this is a DNA polynucleotide, now draw the complementary strand, using the same symbols for phosphates (circles), sugars (pentagons), and bases. Label the bases. Draw arrows showing the 5'→3' direction of each strand. Use the arrows to make sure the second strand is antiparallel to the first. Hint: After you draw the first strand vertically, turn the paper upside down; it is easier to draw the second strand from the 5′ toward the 3′ direction as you go from top to bottom.

In the field of nanotechnology, DNA is used like Velcro to assemble tiny particles into structures that are < 0.0001 mm in size. Draw a model to illustrate how two particles (a circle and a square) could be brought together by linking them to short single-stranded DNA molecules. If the DNA sequence linked to the circle is GGATC, then provide the sequence linked to the square and identify the 5′ and 3′ ends of each strand.