SHEDDING LIGHT ON DNA REPLICATION
Celia Henry Arnaud · Chemical & Engineering News · 2006
UNDERGRADUATE BIOLOGY STUdents could be forgiven for thinking that scientists have DNA replication all figured out. After all, textbooks present the models of replication so matter-of-factly that it's easy to forget that many details are understood poorly, if at all. Recently published research sheds light on some of the gaps in our understanding of this key cellular process. During replication, the DNA must be unwound and separated into its two strands by an enzyme known as helicase. Each of the strands is then copied separately. DNA polymerase, the enzyme that synthesizes new DNA, can't start copying DNA on its own. It requires short pieces of RNA known as primers to jump-start the process. One of the challenges in DNA replication is keeping the two strands in sync. Because DNA can be copied only in the 5' to 3' direction, the correctly oriented strand, known as the leading strand, can be copied continuously as DNA polymerase ...