Question

The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle of yeast cells grown in the nutrient-rich environment

Answer 1

Answer:

Upon nutrient limitation, budding yeast will produce daughter cells less than 20% of the mother cell size. This asymmetric division may select for growth functions that are efficient over a larger range in cell sizes, such as exponential growth. In turn, efficient growth over a large size range lessens the pressure to have precise size control.

Explanation:

In wild-type cells growing in nitrogen-rich medium, the size threshold to enter mitosis is high, and the G1/S size control is cryptic because cell division produces daughter cells with a size greater than the minimum required to initiate S phase. In these conditions, G2 is long and G1 is short. However, the cell size threshold to enter mitosis is greatly reduced when wild-type cells are shifted to medium with a poor nitrogen source, such as minimal medium with proline, isoleucine, or phenylalanine. In these conditions, wild-type cells initiate mitosis at a reduced cell size, generating two daughter cells that are smaller than the critical size threshold required to progress through G1/S