Lecture 4: Mitosis and
Meiosis
Allen Lewis Malisa, PhD
Department of Biological Sciences, Faculty of Science
Solomon Mahlangu (Mazimbu) campus
, Mitosis: In The Beginning One
Every organism, including you, begins as a single cell.
Some organisms remain a single-cell their entire lives.
Each single-celled organism reproduces by forming two new
offspring cells. Usually these cells separate.
However, in some types of single-celled organisms, the offspring
cells stick together and form a colony of many cells.
A multi-celled organism begins as a single cell that divides and
forms two new cells that stay together.
Those two cells divide and form four new cells.
The cells continue to divide, forming many new cells.
, Mitosis…
Groups of cells become specialized forming tissues, organs and
systems that carry out the life processes.
Your body is constantly making new cells.
Cell division plays a very important role in the life cycle of a cell.
Without cell division, all living organisms would fail to reproduce,
eventually dying out.
The new cells replace old cells that have died.
The new cells also allow you to grow in size.
Like many things, cells wear out and die.
If an organism is to live and grow, it must reproduce.
Therefore cell division serves an important role in an organism's
health and growth.
Cell division occurs rapidly in living organisms. For example, in an
adult human, millions of cells divide each second to maintain
homeostasis
, Fertilization Results In A
Diploid Zygote
Egg Haploid
1n nucleus
Sperm
Haploid
nucleus 1n
Meiosis
Allen Lewis Malisa, PhD
Department of Biological Sciences, Faculty of Science
Solomon Mahlangu (Mazimbu) campus
, Mitosis: In The Beginning One
Every organism, including you, begins as a single cell.
Some organisms remain a single-cell their entire lives.
Each single-celled organism reproduces by forming two new
offspring cells. Usually these cells separate.
However, in some types of single-celled organisms, the offspring
cells stick together and form a colony of many cells.
A multi-celled organism begins as a single cell that divides and
forms two new cells that stay together.
Those two cells divide and form four new cells.
The cells continue to divide, forming many new cells.
, Mitosis…
Groups of cells become specialized forming tissues, organs and
systems that carry out the life processes.
Your body is constantly making new cells.
Cell division plays a very important role in the life cycle of a cell.
Without cell division, all living organisms would fail to reproduce,
eventually dying out.
The new cells replace old cells that have died.
The new cells also allow you to grow in size.
Like many things, cells wear out and die.
If an organism is to live and grow, it must reproduce.
Therefore cell division serves an important role in an organism's
health and growth.
Cell division occurs rapidly in living organisms. For example, in an
adult human, millions of cells divide each second to maintain
homeostasis
, Fertilization Results In A
Diploid Zygote
Egg Haploid
1n nucleus
Sperm
Haploid
nucleus 1n
