Compare and contrast mitosis and meiosis.?

Answer 1

Meiosis occurs in germ cells of the testes and the ovaries while mitosis occurs in somatic cells, Meiosis is a reduction cell division while mitosis is an indirect cell division.

Mitosis results in 2 daughter cells with diploid number of chromosomes and during it no crossing over occurs and consequently no gene exchange takes place and is composed of single nuclear division. During Ana phase the chromosome divides longitudinally at the centromere into 2 chromatids.

Meiosis results in 4 daughter cells with haploid number of chromosomes and is composed of two successive divisions first and second meiotic division.
The first meiotic division includes crossing over during pairing which leads to gene exchange and during the anaphase each chromosome of a bivalent moves towards one pole of the cell which results in 2 cells with haploid number of chromosomes.
The second meiotic division is similar to mitosis but without prior duplication of DNA producing 4 daughter cells with haploid number of chromosomes.(it is longer than the first meiotic division).

Answer 2

According to Wikipedia Meiosis is: http://en.wikipedia.org/wiki/Meiosis
"In biology, meiosis (IPA: /maɪˈəʊsɪs/) is the process by which one diploid eukaryotic cell divides to generate four haploid cells often called gametes. The word "meiosis" comes from the Greek meioun, meaning "to make smaller," since it results in a reduction in chromosome number in the gamete cell. Among fungi, spores in which the haploid nuclei are at first disseminated are called meiospores, or more specifically, ascospores in asci (Ascomycota) and basidospores on basidia (Basidiomycota)."

According to Wikipedia Mitosis is: http://en.wikipedia.org/wiki/Mitosis
"Mitosis is the process in which a cell duplicates its chromosomes to generate two identical cells. It is generally followed by cytokinesis which divides the cytoplasm and cell membrane. This results in two identical cells with an equal distribution of organelles and other cellular components. Mitosis and cytokinesis jointly define the mitotic (M) phase of the cell cycle, the division of the mother cell into two sister cells, each with the genetic equivalent of the parent cell. Mitosis occurs most often in eukaryotic cells."

In meiosis the cell divides into 4 and each cell has to share the chromosomes so it only has a copy of the original chromosomes, not the extras chromosomes formed when the cell gets ready to divide. Therefore the original creature creates a total duplicate, a clone of itself. This is similar to the binary form of replication used by archaea or bacteria where it forma a bud and splits in half forming an exact duplicate of itself. Evolution happens when errors in replication are made or when radiation induces a change.

With binary reproduction all the new versions will be the same, there will be no evolution or changes. In meiosis it would be the same, unless two different forms of the same life form unite to multiply. Evolution is possible, but only half as possible as it is with mitosis.

In mitosis then when the cell divides the new cell has both pair of chromosomes, this is how humans and most higher life forms reproduce. Evolution is common since the parents both contribute to the new life.

If you reproduced by meisosis then half the time your parents would produce a clone of themselves. The other half of the time there could be an evolutionary change.

Since you reproduce by mitosis both sets of chromosomes are shared by the new child so it becomes a function of this blending. Evolution is more common because of this blend. It is as possible that bad genes which were suppressed in the parents could express themselves in the child.

The kings and queens of Medieval Europe were considered to be divine so they did not reproduce with commoners. Haemophilia (http://en.wikipedia.org/wiki/Haemophilia), a blood disorder that prevents the blood from clotting, developed in the children. Only when the kings and queens of Europe stopped breeding with themselves did they cure this problem. That is why it was important that Diana, who was made Princess by marrying Prince Charles, was a commoner. Her sons have a new combination of genes and less of a chance of caring a fatal gene disorder.

Mitosis is a superior form or reproduction because it allows more change than mesiosis. Successful life forms that use mesiosis evolve slower since the chromosome are not shared, but replicated. In effect clones are made half the time instead of all new individuals as happens in mitosis. This is why all of the major life forms use mitosis. Only some life forms like fungi and many protozoa and sea urchin use mesiosis to reproduce.