Download Mitosis, Meiosis, Cloning and Genetic Variations

Mitosis, Meiosis, Cloning and Genetic Variations
Mitosis and meiosis are important types of cell division that occur in living organisms. Both cell
divisions have key similarities in their stages and processes, as well as key differences that are
specifically related to the purpose of the type of cell division.
Question ONE
Compare mitosis and meiosis by explaining where each type of division occurs in humans and the
purpose of each type of cell division.
Also discuss the importance of the number of chromosomes and the number of daughter cells that
are produced and if generic variation in the daughter cells is important or not.
Mitosis
Where: Every cell of a human body except in the reproductive organs.
Purpose: For growth and repair of a cell
Daughter cells: 2, each carrying the same number of the chromosomes in the original cell
Variation: there is no variation – otherwise mutation occurs
Meiosis
Where: Reproductive organs testes/ovary
Purpose: To produce gametes sperm/egg
Daughter cells: 4, each carrying the half number of the chromosomes in the original cell
Variation: there are variations due to the differences between the daughter cells produced – results
in the inherited variations among the offspring.
Question TWO
Cloning - the parent cell is fused with an enucleated fertilised egg cell and implanted in the uterus
of the surrogate cow.
Cloned individuals are genetically identical to the parent from which they came. This is because
they are formed by mitosis / asexual reproduction.
Sexual reproduction is fusion of the sperm and egg, which have been produced through meiosis.
Sexual reproduction uses meiosis to produce gametes with half the chromosome number.
The new offspring are different / have variation due to independent assortment during meiosis and
fusion of gametes containing chromosomes from both parents.
Advantages of cloning:
1. can ensure that cloned individuals will be of the same quality as the parent
2. growth-only process used
3. resulting offspring all identical
4. quick way of producing new herd.
Advantage of sexual reproduction is that it allows for variation to respond to change etc.
Disadvantage of sexual reproduction is that it may produce offspring without a desired
characteristic.