Question

During which stage of the cell cycle is the chromosome content of a mammalian liver cell 1n?

a. G1

b. S

c. G0

d. M

e. None of the above

Answer 1

In mammals including humans the chromosome content in somatic cells or the non-reproductive cells is 2n. 1n number of chromosomes is found only in the gametes or the reproductive cells. For example, human somatic cells have 23 pairs of chromosomes or 46 number of chromosomes (2x23=46). 1n that is 23 chromosomes are present in the reproductive cells. In G0 phase the cell is in a quiescent state with 2n number of chromosomes. In S phase the DNA is replicated.Since the DNA is replicated, the total chromosome content in a somatic cell like the liver cell would be 2x2n. G1 phase of cell cycle is the phase during which the somatic cell prepares itself for the synthesis or S phase. So, in this phase the chromosome content of the somatic cell would be 2n. In the M phase the mother cell divides into two genetically identical daughter cells. In this phase, the replicated genetic material is distributed equally between the two newly formed daughter cells. So, the chromosome content of the cell at the end of this phase will also be 2n.So, the correct option is option E, none of the above.