Question

If the new organism has 10 chromosomes, how many chromosomes does it get from its parent?

Answer 1

Answer:

Cytokinesis results in 2 daughter cells, and I am assuming you refer to one of these daughter cells because the parent cell will be no more after cytokinesis.

I am also assuming that this question is asked in relevance to mitosis.

The answer is 10, because mitosis produces two genetically similar daughter cells. Here’s why:

The term chromosome is usually used to refer to one molecule of DNA, and the number of chromosomes is a characteristic of the organism. So this organism’s cells have 10 chromosomes, and therefore, 10 molecules of DNA to begin with. This is true during the G1 phase of interphase. However, during the S phase of interphase, the DNA is replicated. Therefore at the S phase, the cell has 20 molecules of DNA.

The chromosomes as seen during prophase have 2 sister chromatids joined at the centromere. Each sister chromatid contains one molecule of DNA and is a copy of each other. Therefore each chromosome at prophase has 2 molecules of DNA. Therefore, the cell still has 10 chromosomes but 20 DNA molecules: this maintains the idea that the number of chromosomes are a characteristic of the species, because if “chromosome” was still used to refer to one molecule of DNA, the cell will have 20 “chromosomes”, and this can’t be true of the species. This method avoids confusion.

In metaphase, the chromosomes, still with 2 sister chromatids, line up along the metaphase plate and the spindle fibres attach to the centromere of each chromosome at the kinetochore. Even in metaphase, the cell has 10 chromosomes and 20 DNA molecules.

In anaphase the sister chromatids (which can now be referred to as chromosomes) are pulled apart and towards each opposite pole.

This is followed by telophase where each chromatid/chromosome at each pole de-condenses and the nuclear envelope reforms around them. At this stage, the parent cell has 2 nuclei each with 10 chromosomes.

This is followed by cytokinesis which results in two daughter cells each with 10 chromosomes.