Mitosis and meiosis are two types of cell division. Mitosis produces two daughter cells that are identical to the parent cell and occurs in somatic (body) cells. The DNA replicates and chromosomes condense and separate into two identical daughter cells. Meiosis produces four haploid gametes through two cell divisions and occurs in sex cells. During meiosis, one round of DNA replication is followed by two cell divisions, resulting in four daughter cells each with half the number of chromosomes as the original parent cell. The major difference between mitosis and meiosis is that mitosis maintains chromosome number while meiosis halves the chromosome number.

1. CELL DIVISION
Mitosis and Meiosis

2. DNADNA is the molecule that stores hereditary or
genetic information inside a cell and transmits it to
other cells during cell division
Below you can see a model of the double helixdouble helix shape of
DNA:

3. When a cell is dividing, DNA winds up tightly and forms
chromosomeschromosomes in the nucleus of the cell.

4. The specific portion of the DNA code with genetic
information to synthesize a protein is called a genegene. Genes
are contained within the chromosomes.

5. A karyotype is a
picture showing the
arrangement of a
full set of human
chromosomes.
Humans have 46 (or 23
pairs of) chromosomes

6. Animal Somatic Cells (cells of the body) are diploid.
This means that each cell has two chromosomes of
each type. They are in PAIRS.
Gamete cells (egg, sperm) are haploid. This means
that each cell has only one of each type of
chromosomes.
Biologists use “2n” to symbolize diploid and “n” to
symbolize haploid.

7. MITOSIS: When somatic (body) cells reproduce
themselves the process is called MITOSIS. All
somatic cells are diploid (2n) and both daughter cells
produced are also diploid.
Mitosis leads to the production of two “daughter
cells”. Each daughter cell has the same number of
chromosomes as the parent cell:
A somatic Cell 2n  Two Daughter Cells 2n

8. INTERPHASE - DNA replicates
PROPHASE - diffuse chromatin
condenses into discrete chromosomes
PROMETAPHASE - chromosomes
move toward the “equatorial plane”
METAPHASE - chromosomes
are lined up at the equatorial plane
(also called the metaphase plate)
ANAPHASE - Sister chromatids
disjoin and migrate to opposite poles.
TELOPHASE - chromosomes decondense
and a cleavage or furrow begins to form in the
middle of the cell. Finally, the cell divides into
two: this is called cytokinesis.cytokinesis.
The steps of Mitosis:The steps of Mitosis:

9. MEIOSIS
The process that form gametes (sperm or
egg) is called MEIOSISMEIOSIS. During meiosis, a
single diploid cell divides and produces
FOUR haploid reproductive cells.
n
2n
n
Mother cell
n n
In Meiosis there is one chromosome
duplication followed by two cellular
divisions (into four cells) so Meiosis
comprises two stages: Meiosis I and II.
n egg
n sperm
Through
fertilization, an
n sperm joins
with an n egg
and form a 2n
zygote .
2n zygote
Gamete Cells

10. The steps of Meiosis I

11. The steps of Meiosis II:Meiosis II:

12. What is the MAJOR
difference between
these two processes?
MITOSISMITOSIS keeps the
same chromosome
number :
2n  2n
Whereas MEIOSISMEIOSIS
halves the chromosome
number:
2n  n

13. And Crossing overCrossing over
that only occurs
during meiosis and
originates
recombinantrecombinant
cromosomescromosomes
This way most gametes are
different, which has lead
living beings to variability

14. Any questions?
Thanks for your attention

15. Adapted from:
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookDNAMO
http://edweb.sdsu.edu/ltca/Mitosis_Meiosis_files/frame.htm#slide
by: Christianna Antonello