PURPOSE OF MEIOSIS / REDUCTION DIVISION
Meiosis is known as reduction division because the diploid [2n] number of
chromosomes in the mother cell is educed to the haploid [n] number in the daughter
cells during this division process. Each daughter cell has half the number of
chromosomes of the original other cell.
― The purpose of meiosis / reduction division is the formation of gametes / sex cells
in the sex organs of animals.
― This process of gamete formation is known as gametogenesis.
o When sperm is formed, it is known as spermatogenesis.
o When eggs are formed, it is known as oogenesis.
― In animals, spermatogenesis occurs in the testes and oogenesis occurs in the
ovaries.
IMPORTANCE OF MEIOSIS
― During meiosis, the chromosome number is halved, from the diploid to the haploid
number. This prevents the chromosome number of an organism doubling w. each
generation.
― Gametes w. different gene combinations are produced during meiosis. This leads
to genetic variation in a population.
GENETIC VARITATION
― Variation is the differences that occur, as a result of different gene combinations,
between organisms of a species.
― Each individual has its own unique combination of genes.
Different gene combinations in gametes are obtained by;
― Crossing over of chromatids and the exchange of genetic material during
Prophase I. A reshuffling / recombination of genes occurs which means every
gamete formed by an individual has a different genetic composition.
― Random assortment of chromosomes on the equator during Metaphase I.
the homologous chromosomes of a bivalent are arranged on the equator
independently of each other. This independent assortment of chromosomes leads
to a greater variation in the gametes.
― Random fertilisation: the possibility of which sperm will fuse w. which egg in
Gregor Mendel, also known as the “Father of Genetics”, called this phenomenon the
Law of Independent Assortment.
fertilisation also results in a wealth of possible gene combinations in the zygote.
Consequently, the new individual will have a unique gene combination. It will
differ from those of the parents as well as those of any other offspring produced
by the same parents.
Meiosis is known as reduction division because the diploid [2n] number of
chromosomes in the mother cell is educed to the haploid [n] number in the daughter
cells during this division process. Each daughter cell has half the number of
chromosomes of the original other cell.
― The purpose of meiosis / reduction division is the formation of gametes / sex cells
in the sex organs of animals.
― This process of gamete formation is known as gametogenesis.
o When sperm is formed, it is known as spermatogenesis.
o When eggs are formed, it is known as oogenesis.
― In animals, spermatogenesis occurs in the testes and oogenesis occurs in the
ovaries.
IMPORTANCE OF MEIOSIS
― During meiosis, the chromosome number is halved, from the diploid to the haploid
number. This prevents the chromosome number of an organism doubling w. each
generation.
― Gametes w. different gene combinations are produced during meiosis. This leads
to genetic variation in a population.
GENETIC VARITATION
― Variation is the differences that occur, as a result of different gene combinations,
between organisms of a species.
― Each individual has its own unique combination of genes.
Different gene combinations in gametes are obtained by;
― Crossing over of chromatids and the exchange of genetic material during
Prophase I. A reshuffling / recombination of genes occurs which means every
gamete formed by an individual has a different genetic composition.
― Random assortment of chromosomes on the equator during Metaphase I.
the homologous chromosomes of a bivalent are arranged on the equator
independently of each other. This independent assortment of chromosomes leads
to a greater variation in the gametes.
― Random fertilisation: the possibility of which sperm will fuse w. which egg in
Gregor Mendel, also known as the “Father of Genetics”, called this phenomenon the
Law of Independent Assortment.
fertilisation also results in a wealth of possible gene combinations in the zygote.
Consequently, the new individual will have a unique gene combination. It will
differ from those of the parents as well as those of any other offspring produced
by the same parents.
