Question

At a basic level mitosis and meiosis are similar processes. However, they have very different outcomes. Which of the following statements describes an important outcome difference?A. Sister chromatids are separated in meiosis but not in mitosis.B. Sister chromatids are separated in mitosis but not in meiosis.C. Homologous chromosomes are separated in meiosis but not in mitosis.D. Homologous chromosomes are separated in mitosis but not in meiosis.E. None of the above describes a difference between mitosis and meiosis.

Answer 1

Answer: C. Homologous chromosomes are separated in meiosis but not in mitosis.

Explanation: There are two main types of division that take place in eukaryotic cells, mitosis, and meiosis. Mitosis is the type of division that is used for growth, repair, and replacement of tissues. Therefore it is not necessary that the cells have  different chromosome numbers or are varied genetically in the daughter cells in the case of mitosis.

Meiosis is the division that takes place to form the gametes for sexual reproduction. It is important in the first stages of meiosis I, to introduce variation and to halve the chromosome number.

Chromosomes numbers are halved (from 46 to 23) during meiosis I because the gametes (sperm and egg) come together and fuse during fertilization to form a zygote. When this fusion occurs (23 from the zygote and 23 from the egg), the chromosome number needs to be returned to that of the parent cell (46).

Genetic variation is introduced during synapsis which only occurs in meiosis, not mitosis. Homologs exchange genetic information during crossing over of synapsis. Entire chromosomes also separate during meiosis I.

At the end of meiosis, four genetically unique cells are  produced with half the number of chromosomes as the parent cell (23 cromosomes) . After the process of mitosis is completed, two cells genetically identical to each pther are produced and have the same number of chromosomes as the parent cell (46 cromosomes).

Genetic variation is actually important because of changing environmental conditions.