Contains content on cell division.

1. CELL DIVISION
MITOSIS FOR GRADE 10

2. CONCEPT OF MITOSIS
 Plants and animals are known to undergo sexual reproduction.
 Sexual reproduction results in the formation of single cells called
Zygotes.
 This zygote is made up of million of cells and must develop.
 Therefore these single cells must divide many times in order for the
zygote to grow and develop into an adult.
 This type of cell division that takes place is known as Mitosis.
 Mitosis can therefore be defined as a process where by one cell
divides to form two cells that are identical to each other and the
parent cell which the two cells come from
 Therefor only body or sometic cells undergo mitosis.(somatic cells
are all cell other than sex cell)

3. CHROMOSOMES
 Chromosomes are formed when the chromatin network, which is
situated in the nucleus, coils up, thickens and shorten.
 Chromosomes are known to be made up of DNA,
 and DNA contains the genetic code for controlling the appearance
and function of thousands of cells.
 Different organisms are known to have different number of
chromosomes.
 Humans therefore have 46 chromosomes (23 pairs)
 They are also arranged in identical pairs.
 One chromosome consist of 2 chromatids and only one centromere
that attach the two chromatids together.
 Chromosomes are known to be visible only during cell division.

4. CHROMOSOME STRUCTURES

5. WHY IS MITOSIS IMPORTANT?
Reproduction in some simple organisms.
Repairing of damaged cells/tissues.
Replacing of dead cells/tissues.
Mitosis allows organisms to grow.

6. THE CELL CYCLE
Mitosis refers to the division of the nucleus only
into two nuclei, therefore interphase and
cytokinesis are not part of the process of mitosis.
The cell cycle is therefore:
Interphase(this includes G1,S-[DNA synthesis] and
G2phase.
Mitosis.
Cytokinesis
Growth
This results in the formation of two identical cells.

7. THE PROCESS OF MITOSIS
Consist of the following phases:
Interphase
Prophase
Metaphase
Anaphase
Telophase

8. INTERPHASE
• In this phase, the cell prepares for cell division
,this is by building up enough energy.
• The DNA replicates(doubles) itself, so that the
genetic material is double.

9. PROPHASE
The nuclear envelop and nucleolus disappears.
The chromatin network becomes tight and then coils
up and is now visible as chromosomes.
Chromosomes now arrange randomly within the cell
Centrioles move to the opposite ends with spindle
fibres between them.

10. METAPHASE
The chromosomes arrange themselves randomly
along the equator of the cell, each are attached to a
spindle fibre.
The centriole have now finally reached the opposite
poles, attached to the chromosomes by means of a
spindle fibres to the centromere.

11. ANAPHASE
• Spindle fibres now pulls tight , thus splitting the
chromosomes into two chromatids splits into two.
• The centromere that attaches the two chromatids
also splits into two.
• The two daughter chromosomes then move to the
opposite poles

12. TELOPHASE
• Now two groups of chromosomes occur, the occur at
opposite ends.
• The nucleus envelop now surrounds the
chromosomes at the opposite poles.
• Nucleolus now reappears at each poles.
• The chromosomes now become less dense and now
are visible as chromatin network

13. LATE TELOPHASE
• Invagination of the cytoplasm and the plasma
occurs.
• This then goes on until the cell has totally
divided into two separate identical cells.

14. MITOSIS PROCESS