Gene families may be dispersed. The alpha globin genes are on a different chromosome from the beta globin cluster. Similarly, most members of the collagen gene family are dispersed. E. Replication 1. Replication starts at a unique site called the origin of replication.
Replication proceeds bidirectionally, i.e., in both directions, meaning there are two forks.
The fork is composed of the leading and lagging strands. DNA polymerases attach dNTP to primers using base complementarity. The lagging strand is replicated by Okazaki fragment formation requiring a primase to prime DNA polymerase and ribonuclease H and DNA ligase to join fragments. DNA repair systems are present to recognize, remove and replace DNA damaged by chemical changes including UV irradiation. UV light causes adjacent thymine residues to covalently attach to each other.