Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 3

More DNA Replication. The following are observations from five experiments carried out to determine the mechanism of DNA replication in the hypothetical organism Fungus mungus. For each experiment, indicate whether the results support (S), refute (R), or have no bearing (NB)on the hypothesis that this fungus replicates its DNA by the same mechanism as that known for E. coli. Explain your reasoning in each case.
(a)Neither of the two DNA polymerases of F. mungus appears to have an exonuclease activity.
(b)Replicating DNA from F. mungus shows discontinuous synthesis on both strands of the replication fork.
(c)Some of the DNA sequences from F. mungus are present in multiple copies per genome, whereas other sequences are unique.
(d)Short fragments of F. mungus DNA isolated during replication contain both ribose and deoxyribose.
(e)F. mungus cells are grown in the presence of the heavy isotopes 15 N and 13 C for several generations and then grown for one generation in normal ( 14 N, 1 2 C)medium; then DNA is isolated from these cells and denatured. The single strands yield a single band in a cesium chloride density gradient.