Question

g Take your chromosomes through S (synthesis) phase. a. How many chromosomes are in the cell?__________ b. How many chromatids are in the cell? ___________c. Is the 2n number the same before and after the S phase? ____________________

Answer 1

In S or synthesis phase, DNA content of the cell gets doubled. If 2c is the DNA concentration of the cell before S phase then 4c will be the concentration of the DNA after completion of S phase.

However, the chromosome number remains the same.

It is achieved by formation of sister chromatid in the chromosome.

For example, in human cell chromosome number remains the same after S phase, that is, 46.

However, the chromatid number gets doubled, that is, 92.

Thus, the 2n (i.e., 46) number remains the same before and after the S phase.