Question

1. keeping in mind the events of each part of the cell cycle, mark with a double arrow on model 1 where those cells might (either temporarily or permanently) exit the cell cycle to ( g_0 ). label this as ( g_0 ). why did you choose this location for ( g_0 )? hint: think of a place in the cell cycle where the cell is functioning normally, but not preparing to divide.

Explanation:

The $G_0$ phase is a resting state where cells perform normal functions but do not prepare for division. Cells exit the cell cycle into $G_0$ after the $G_1$ phase (before the $G_1/S$ checkpoint), as this checkpoint determines if a cell will commit to division. Cells that do not meet the requirements for division (or are terminally differentiated) enter $G_0$ here, as they are in a functional, non-dividing state.

Answer:

1. Mark the double arrow leading from the end of the $G_1$ phase (just before the $G_1/S$ transition checkpoint) to a labeled $G_0$ phase.
2. This location is chosen because the $G_1$ phase is when cells grow and carry out normal functions; the $G_1/S$ checkpoint decides if a cell proceeds to divide. Cells that do not commit to division (temporarily or permanently) exit here to enter $G_0$, where they function normally without preparing for mitosis.