The Key Contents from this Module are:
Life begins from a single cell and continues with Regulated Cell Division. Cell division distributes DNA (chromosomes) of a mother cell equally between two daughter cells thereby allowing a cell to proliferate. Cell proliferation is essential for growth, repair and reproduction.
Somatic cells are non-reproductive cells containing two sets of chromosomes.
Gametes are reproductive cells (sperm and egg) containing half as many chromosomes as somatic cells.
Mitosis governs the division of somatic cells. Two daughter cells are produced with the same amount of DNA as the mother cell.
Meiosis governs the division of gametes (sperm and ovum). Four daughter cells are produced with half the amount of DNA as the mother cell.
Common stages of embryonic development are:
In plants, mature cells can "dedifferentiate" and give rise to all the specialized cell types of an organism. Any cell with this potential is said to be "totipotent"
A stem cell is a relatively unspecialized cell that can reproduce indefinitely and differentiate into specialized cells under appropriate culture conditions.
If an environment changes or if individuals move to a new environment, natural selection may result in adaptation to these new conditions, sometimes giving rise to new species. Natural selection weeds out the un-adapted and the best-adapted survive.
Five conditions for Hardy-Weinberg Law:
The population must be very large
The population must be isolated from other population
There should be no mutations
There should be Random mating
There should be no natural selection