A scientist tells you that he has found a cool single-celled organism that is about to divide. He tells you that the homologous chromosomes are not paired, and that it doesn't look like any recombination has occurred. Is the organism dividing by mitosis or meiosis? Explain.

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Solution

Homologous chromosomes
The homologous chromosomes are the chromosomal pair comes from each parent (maternal and paternal)with the same length, centromere position, staining pattern ,same gene sequence and loci .
Meiosis
Meiosis is a reductional division where the number of chromosomes in daughter cells is halved as compared to the parent cell.
It occurs only in gametes.
During meiosis, chiasmata are formed at non-sister chromatids that lead to crossing over which occurs only between homologous pairs of chromosomes.
Consequently genetic recombination or variation occurs in the offspring.
Mitosis
Mitosis is an equational division where the number of chromosomes in daughter cells are same as the parent cell.
Two sister chromatids of each chromosome are separated due to constriction of spindle fibers and move to the opposite poles.
The homologous pairing does not take place.
Thus, the single-celled organism is divided by mitosis.

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