Question

A diploid cell contains 2n=2 chromosomes. What will be the number of DNA strands in this cell at G1, G2, Prophase I and Telophase II (per
nucleus), respectively?

Answer 1

Answer:

A diploid cell, with a chromosome charge of 2n = 2 will have in:

• G1 = 4 strands of DNA, two for each DNA molecule.
• G2 = 8 strands of DNA.
• Prophase I = 8 strands of DNA.
• Telophase II = 2 DNA strands per nucleus.

Explanation:

The cell cycle is divided, broadly speaking, into interphase and cell division (M). The process of division -by mitosis or meiosis- involves a series of intermediate steps that conclude with the production of two identical cells (diploid) or two cells with half the chromosome load (haploid), respectively.

• In the G1 phase the cell is in interphase, so the nuclear DNA has not yet replicated. For a cell with 2n = 2, its nucleus has four strands of DNA.
• In G2 phase, after DNA replication, the number of DNA strands is doubled, so now in the cell nucleus of the cell there are 4 DNA molecules, each with double strands, so there is a total of 8 DNA strands.
• In prophase I of mitosis or meiosis the cell still does not divide there are 4 DNA molecules and 8 DNA strands, as in the previous step.
• In telophase II, which only occurs in meiosis, the chromosome charge has been halved, so each daughter cell will have one chromosome (n = 1), one single DNA molecule and 2 DNA strands per nucleus.