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.
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
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. G1
1 phase
phase
2. S phase
2. S phase
3. G
3. G2
2 phase
phase
8. Interphase
Interphase
1. G
1. G1
1 (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. G2
2 (gap) phase:
(gap) phase:
a. Cellular growth and preparation for M phase
M phase.
11. Answer:
Answer:
• A chromosome
chromosome is made up of a DNA
DNA -
histone protein
histone protein complex called chromatin
chromatin.
•
• Chromatin
Chromatin is a long, thin fiber that is folded
and coiled to form chromosomes
chromosomes.
DNA double helix
Histone
proteins
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 two sister
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.
20. Metaphase
Metaphase
• Shortest phase
•
• 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).
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.