Question

Most melanocytes of the skin are fully differentiated and have long lifespans with low proliferative capacity, similar to neurons. Under certain circumstances, melanocytes can begin to hyperproliferate (divide at a higher than normal rate) leading to melanoma, a common type of skin cancer. Many treatments for cancer seek to disrupt DNA replication since having 2 intact and error-free copies of the genome is required for progression through the cell cycle.

6. As part of your summer research internship, you isolate 100 melanocytes from healthy non-cancerous skin and determine the stage of the cell cycle they were currently in. What stage of the cell cycle would you expect to observe most frequently? How many copies of the genome are present in this cell stage?

Answer 1

The cell cycle contains two stages.
1. Interphase
2. M-phase

Interphase does not involve the division of the cell. However, it prepares the cell for the M-phase.
Interphase contains three sub-stages
i. G1-phase
ii. S-phase
iii. G2-phase

Cells that do not divide further enter into a quiescent state known as the G0 phase. These cells exit the G1 phase and enter into the G0 phase.
Since most of the melanocytes in a normal individual do not divide, they can be found in the G0 phase (Interphase).

DNA replication occurs in the S-phase.
Since G0 phase is before to the S-phase. Cells in G0 phase contains diploid genome (2 sets of genomes)