Question

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

Answer 1

The activities occur in phases G1 and S of the cell cycle, with licensing, helicase deposition, and ORC phosphorylation taking place in G1, and helicase activation occurring in S, leading to the sequence GSNG.

Step-by-step explanation:

Indicate whether each of the following occurs mainly in G1 phase (G), S phase (S), or G2 phase (G2) of the cell cycle:

• DNA helicase activation - S
• DNA helicase deposition on DNA at the replication origins - G1
• ORC phosphorylation - G1
• Licensing of replication origins - G1

The correct four-letter string representing the phases is GSNG.

The G1 phase involves the cell growing rapidly, performing routine metabolic processes, and preparing for DNA replication which includes licensing of the replication origins and ORC phosphorylation. DNA helicase activation and its deposition on DNA at the replication origins to initiate DNA replication take place in the S phase. The G2 phase is for final preparations to divide, which does not include these activities.

Answer 2

the answer is S-G-S-G

Step-by-step explanation:

DNA helicases are enzymes that catalyze the unwinding of the double DNA helix in order to form a replication fork at the origin of replication (i.e., the site where DNA replication starts). DNA replication occurs in a bi-directional manner by two replication forks that move in opposite directions in order to form a replication bubble. The origin of replication is formed during the transition from mitosis to G1 when they are licensed for the subsequent S phase. The origin recognition complex (ORC) is a DNA binding complex that binds to the origin of replication, whose function is to act as a scaffold for the assembly of initiation factors. ORC is phosphorylated during the beginning of the S phase in order to dissociate this complex from chromatin.