Homework 2 Answers
1. The DNA molecule is a double-stranded helix with a sugar phosphate backbone. The nitrogenous bases, which are attached to the sugar phosphate backbone, are located on the interior of the helix. The two strands of the helix are held together as a result of hydrogen bonds joining the complementary bases from each strand.
2. First, the double helix unwinds, and the strands separate, creating a replication fork. DNA polymerase III catalyzes the replication of both strands. The new DNA strand is formed in the 5’ to 3’ direction. A short RNA strand called the primer begins the new strands. The leading strand is the strand with its 3’ end initially exposed, and the lagging strand the one with its 5’ end initially exposed. The lagging strand is formed in fragments called Okazaki fragments, which grow opposite the direction of the movement of the replication fork. Finally, the RNA primer is removed, the gaps are filled by the DNA polymerase I, and the fragments are linked together by DNA ligase.
3. DNA strand: CCAGGTTACTG, RNA strand: CCAGGUUACUG
4. The DNA molecule stores information that can either be replicated or transcribed to produce RNA molecules of various functions. The information stored by the RNA molecules can then be translated to synthesize the proteins that mediate all of the structural and metabolic functions of the cell.