Cell growth briefly at M phase when the nucleus and then the cell divide in two. The process of cell division, called cell cycle, has four major parts called phases. The first part, called G phase is marked by synthesis of various enzymes that are required for DNA replication. The second part of the cell cycle is the S phase, where DNA replication produces two identical sets of chromosomes. The third part is the G phase in which a significant protein synthesis occurs, mainly involving the production of microtubules that are required during the process of division, called mitosis. The fourth phase,
Transfer DNA Transfer DNA The transfer DNA (abbreviated T-DNA) is the transferred DNA of the tumor-inducing (Ti) plasmid of some species of bacteria such as "Agrobacterium tumefaciens" and "[[Agrobacterium rhizogenes](actually an Ri plasmid)]". The T-DNA is transferred from bacterium into the host plant's [[cell nucleus|nuclear]] DNA [[genome]]. The capability of this specialized tumor-inducing (Ti) plasmid is attributed to two essential regions required for DNA transfer to the host cell. As the T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the right border and terminated at the left border and requires the "vir" genes of the Ti plasmid.