MITOSIS (2).pdf

Mitosis

1. MITOSIS MITOSIS

2. Mitosis Mitosis
• The form of cell division
cell division
by which a
eukaryotic somatic cell
somatic cell
duplicates.
••
Mitosis Mitosis
is asexual reproduction.
asexual reproduction.
••
Cell division Cell division
is the continuation of life
based on the reproduction of cells .

3. Mitosis Mitosis
2n=46Liver Cell
2n=46
2n=46
two
identical
daughter
cells
Liver Cell
Liver Cell

4. Somatic Reproduction Somatic Reproduction
• Most eukaryotic cells reproduce asexually by
mitosis
mitosis
.
••
Somatic cells Somatic cells
are all body cells
body cells
(like nerve, (like nerve,
liver, etc...) liver, etc...)
except sperm and ova (egg).
• All Somatic cells have the same number of
chromosomes
chromosomes
.

5. Cell Cycle Cell Cycle
• The dividing
dividing
and non
non
--
dividing dividing
stages in the
life of a cell.
•Phases:
1.1.
Interphase Interphase
: growth and DNA replication
2.2.
Prophase Prophase
3.3.
Metaphase Metaphase
4.4.
Anaphase Anaphase
5.5.
Telophase Telophase
Mitotic division Mitotic division

6. Cell Cycle Cell Cycle
Mitosis -prophase
-metaphase
-anaphase
-telophase
G
1
G
2
S
phase
interphase

7. Interphase Interphase
• Comprises about 90%
90%
of the cell cycle
cell cycle
.
••
Cellular growth Cellular growth
:
a. protein synthesis
protein synthesis
b. metabolic activities
metabolic activities
c. DNA
DNA
synthesis synthesis
• Made up of three phases
three phases
:
1. G 1. G
11
phase phase
2. S phase 2. S phase 3. G 3. G
22
phase phase

8. Interphase Interphase
1. G 1. G
11
(gap) phase: (gap) phase:
a. protein synthesis and metabolic activities. b.most cell are arrested in this phase
most cell are arrested in this phase
.
2. S phase: 2. S phase:
a.DNA
DNA
replication replication
takes place.
3. G 3. G
22
(gap) phase: (gap) phase:
a. Cellular growth and preparation for M phase
M phase
.

9. Interphase Interphase
••
Nucleus Nucleus
and nucleolus
nucleolus
visible.
Nuclear
membrane
nucleolus
cell membrane
chromatin

10. Question: Question:
••
What is a What is a
chromosome chromosome
??

11. Answer: Answer:
•A chromosome chromosomeis made up of a DNADNA-
histone protein histone protein complex called chromatin chromatin .
••Chromatin Chromatinis a long, thin fiber that is folded
and coiled to form chromosomes chromosomes.
DNAdouble helix
Histone
proteins
chromosome

12. Question: Question:
••
What is a replicated What is a replicated
chromosome chromosome
??

13. Answer: Answer:
• A replicated chromosome
chromosome
consist of two
strands of identical chromosomal material
called chromatids
chromatids
(sister chromatids
sister chromatids
).
chromatid
chromatid
S phase: chromosomes replicate
chromosome
chromosome
centromere

14. Mitotic Phase Mitotic Phase
••
Mitosis (karyokinesis) Mitosis (karyokinesis) a.nuclear
nuclear
division of genetic material
genetic material
.
b. prophase b. prophase
--
metaphase metaphase
--
anaphase anaphase
--
telophase telophase
••
Cytokinesis Cytokinesis a.a.
cytoplasmic division cytoplasmic division
.
b. Indicator of telophase.

15. Prophase Prophase
••
Longest phase Longest phase
• Nucleolus disappears • Chromatin material condenses into
chromosomes
chromosomes
, consisting of twosister
sister
chromatids chromatids
.

16. Prophase Prophase
••
Centrioles Centrioles
move apart (not found in plants).
••
Spindle fibers Spindle fibers
((
microtubules microtubules
))
form and
attach from centrioles
centrioles
to centromeres by
centromeres by
kinetochores. kinetochores.
• Nuclear envelope fragments and disappears.

17. Prophase Prophase
late prophase late prophase, ,
promethaphase promethaphase
early prophase early prophase
centrioles
centromere
nuclear envelope
disappearing

18. Question: Question:
••
What attaches the What attaches the
spindle fibers spindle fibers
to to
the the
centromeres centromeres
??

19. Answer: Answer:
Kinetochores Kinetochores
sister sister
chromatid chromatid
sister sister
chromatid chromatid
centromere centromere
spindle fiber spindle fiber
kinetochores kinetochores
centriole
aster
fibers

20. Metaphase Metaphase
•Shortestphase ••
Centrioles Centrioles
are at opposite ends of the cell
and attached with aster fibers
aster fibers
.
••
Chromosomes Chromosomes
move to the metaphase
metaphase
plate plate
(equatorial plate
equatorial plate
-center of cell).

21. Metaphase Metaphase
centrioles
spindle fibers
aster
fibers

22. Metaphase Metaphase
•Top of spiralisation, chromatin is in max. of
condensation
•Chromosomes collect at equatorial plate
•At the end of metaphase centromere start
dissapears

23. Anaphase Anaphase
••
Centromeres Centromeres
uncouple and spindle fibers
spindle fibers
shorten.
••
Sister chromatids Sister chromatids
separate and move apart.
• After separation, chromatids
chromatids
are now
considered chromosomes
chromosomes
.

24. Anaphase Anaphase
• During this phase, the cell contains twice
the normal number of chromosomes
chromosomes
.
• Cell begins to elongate
elongate
.
• At the end, there are equal numbers of
chromosomes
chromosomes
at the poles.

25. Anaphase Anaphase
No longer sister chromatids sister chromatids, now chromosomes chromosomes
centrioles
spindle fibers
aster
fibers

27. Telophase Telophase
• Nuclear membrane reappears. ••
Chromosomes Chromosomes
uncoil-despirelationand
decondesation
• In the end, two genetically identical nuclei
(karyokinesis
karyokinesis
completed) are present.

28. Telophase Telophase
cleavage furrow (cytokinesis)
nuclear membrane reforming
nucleolus reappears

30. Cytokinesis Cytokinesis
••Cytoplasmic division Cytoplasmic division
••Cell plate Cell plate complete in plants plants
• In the end, two separate daughter cells
produced with single nucleus.
cell plate