Indicate whether each of the following occurs mainly in G1 phase (G), S phase (S), or G2 phase (H) of the cell cycle. Your answer would be a four-letter string composed of letters G, S, and H only, e.g. HGSS. DNA helicase activation DNA helicase deposition on DNA at the replication origins ORC phosphorylation ()Licensing of replication origins (1 point) SGGH ? a. GGSG b. GGSH c. SHSG d. SGSG

The cell cycle consists of G1, S, G2 and M phase. The former three phases include the interphase and M phase is the dividing phase of cell . G1 prepares cell for DNA synthesis. S phase is the phase where DNA replication takes place. G2 phase prepares cell for cell division or M phase.

G1 phase preceeds replication or S phase and G1 phase licences DNA replication.

During other phases of cell cycle, ORC complex masks origin of replication. ORC phosphorylation takes place at S phase, which removes this omplex and unmasks origin of repication site so that replication machinery can bind to it.

DNA helicase activation: S phase

DNA helicase deposition on DNA at the replication origins: G phase (actually G1)

ORC phosphorylation: S phase

Licensing of replication origins : G phase (actually G1)

Hence correct choice should be:

SGSG