Write information about mitosis and meiosis
Answers
Answer:
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Explanation:
Mitosis
Mitosis is a continuum of changes but biologists like break down the stages of mitosis into four main stages, prophase, metaphase, anaphase and telophase.
The focus in this class is on an understanding of the process and not memorization of phases.
The only phase name you will need to remember is metaphase.
In mitosis the nuclear membrane is broken down, spindle fibres (microtubules) attach to the chromatids at the centromere and pull apart the chromatids.
When the chromatids reach separate ends of the cells the spindle fibres disintegrate and a nuclear membrane rebuilds around the chromosomes making two nuclei.
Each nucleus is identical to the original nucleus as it was in G1.
Meiosis
Meiosis is the form of nuclear cell division that results in daughter cells that have one half the chromosome numbers as the original cell.
In organisms that are diploid, the end result is cells that are haploid. Each daughter cell gets one complete set of chromosomes, i.e., one of each homologous pair of chromosomes.
In humans, this means the chromosome number is reduced from 46 to 23.
The only cells that undergo meiosis will become sperm or eggs.
The joining together of a sperm and egg during fertilization returns the number of the chromosomes to 46.
Cells that undergo meiosis go through the cell cycle including the S phase so begin the process with chromosomes that consist of two chromatids just as in mitosis.
Meiosis consists of meiosis I and meiosis II. In meiosis I homologous chromosomes are separated into different nuclei.
This is the reduction division; chromosome number is cut in half. Meiosis II is very similar to mitosis, chromatids are separated into separate nuclei.
As in mitosis, it is spindle fibres that “pull” the chromosomes and chromatids apart.
The end result of meiosis is four cells, each with one complete set of chromosomes instead of two sets of chromosomes.
Answer:
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Explanation:
Mitosis
Involves one cell division?
Results in two daughter cells
Results in diploid? daughter cells? (chromosome? number remains the same as parent cell)
Daughter cells are genetically identical
Occurs in all organisms except viruses
Creates all body cells (somatic?) apart from the germ cells? (eggs and sperm)
Prophase is much shorter
No recombination/crossing over occurs in prophase.
In metaphase individual chromosomes (pairs of chromatids) line up along the equator.
During anaphase the sister chromatids are separated to opposite poles.
Meiosis
Involves two successive cell divisions
Results in four daughter cells
Results in haploid? daughter cells (chromosome number is halved from the parent cell)
Daughter cells are genetically different
Occurs only in animals, plants and fungi
Creates germ cells (eggs and sperm) only
Prophase I takes much longer
Involves recombination/crossing over of chromosomes in prophase I
In metaphase I pairs of chromosomes line up along the equator.
During anaphase I the sister chromatids move together to the same pole.
During anaphase II the sister chromatids are separated to opposite poles.