What would happen if sperm and egg were produced by mitosis?


What would happen if sperm and egg were produced by mitosis?


Mitosis, the cell division that produces two daughter cells from a single mother cell. The daughter cells are identical in ploidy and genetic content to each other and to the mother cell. Therefore, if the mother cell is diploid (possessing two sets of all chromosomes), the daughter cells also will be diploid. If the mother cell is haploid (possessing one set of all chromosomes), then the daughter cells also will be haploid.

Answer and Explanation:

If the sperm and eggs of a diploid species such as humans were produced by mitosis, these reproductive cells would be diploid as well. Fertilization of a diploid egg by a diploid sperm would produce a tetraploid zygote that has four sets of all chromosomes. The somatic cells produced from this tetraploid zygote would also be tetraploid. If these tetraploid individual made gametes by mitosis, the subsequent generation would double in number of chromosomes. This could not be sustained. In sexual life cycles, fertilization and meiosis alternate to maintain a constant number of chromosomes within the species.

In addition to meiosis producing gametes that have half the number of chromosomes, meiosis produces genetic variation among gametes through crossing over and independent assortment of different pairs of chromosomes in the first division. This genetic variation is one of the evolutionary advantages of meiosis and sexual reproduction. Mitosis would not produce genetic variation among gametes.

Learn more about this topic:

Gametes: Definition, Formation & Fusion

from Biology 102: Basic Genetics

Chapter 6 / Lesson 16

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