The Process of Meiosis in an animal cell

1. The Process of Meiosis in an
Animal Cell.
by
Mr. Muhammad Shokat Zaman
M.Phil (Education)
EST
AT
FG Public Middle School Shorkot Cantt

2. SCHEME OF PRESENTATION
 Definition of Meiosis
 Divisions of Meiosis
 Meiosis I
 Prophase I
 Metaphase I
 Anaphase I
 Telophase I
 Meiosis II
 Meiosis II
 Prophase II
 MetaphaseII
 Anaphase II
 Telophase II

3. Definition of Meiosis
Meiosis occurs in the special cells of
sex organs. In a sexually reproducing
organism, meiosis is the division of a
single nucleus into four daughter cells
in which the number of chromosomes
becomes half.

4. Divisions of Meiosis
Meiosis has two
clear divisions;
Meiosis I and
Meiosis II

5. Meiosis I
 This is made up of 4 stages Prophase,
Metaphase Anaphase and Telophase.

6. Diagram Meiosis I

7. Prophase I
 The chromosomes shorten, thicken and become
visible under the light microscope. During
prophase 1 each chromosome divides into a pair
of identical chromatids joined by the centro
mere. Identical chromosomes called
homologous chromosomes pair up forming
homologous pairs. The nuclear membrane
disappears and homologous pairs of
chromosomes line up on the middle of the
cell. The spindle fibres will start to form.

8. Metaphase I
 Homologous pairs of chromosomes
line up on the middle of the cell. The
chromosomes are attached to the
spindle fibres by their centromeres.

9. Anaphase I
The spindle fibres shorten and the chromosomes
separate going to opposite poles of the cell.

10. Telophase I
 The chromosomes gather at opposite end
of the cell. Nuclear envelope forms around
each set of chromosomes and the
chromosomes start to uncoil. Spindle
fibres start to breakdown.The cytoplasm
pinches in half. Each daughter cell has a
half set of chromosomes the parent
cell.

11. Meiosis II
 The stages of Meiosis II are actually
very similar to Mitosis.

12. Meiosis II

13. The Stages of Meiosis II
Prophase II
Two cells were formed at the end of Meiosis I.
During prophase II the nuclear envelope breaks
down, spindle fibres form and the chromosomes
shorten and thicken.
Metaphase II
The chromosomes align themselves along the
equator. They are attached to the spindle fi
bres by their centromeres.
Anaphase II
Spindle fibres shorten separating the chromatids.
This pulls the chromatids to opposite poles

14. Telophase II
The nuclear envelope forms around each set of
chromosomes. Chromosomes uncoil. Also as a result of
cytokinesis, the cells will split to form 4 daughter cells.

15. ALLAH HAFIZ