KEY ROLES OF CELL DIVISION
-Ability of organisms to produce more of
their own kind.
-the continuity of life is based on the
reproduction of cells, or cell division.
- ASEXUAL REPRODUCTION
- GROWTH , REPAIR, & DEVELOPMENT of
eukaryotes
-TISSUE RENEWAL, CELL CYCLE
CELL DIVISION -an integral part of the cell
cycle, the life of a cell from formation to
its own division.
- Most cell division in 2 daughter cells
(MITOSIS produce 2 identical daughter
cells from the parent cell) with identical
genetic information. Exception is
MEIOSIS – special type of division that
can produce sperm and egg cells,
produce 4 daughter cells that are distinct.
CELLUL AR ORGANIZATION OF THE
GENETIC MATERIAL
- All the DNA in a cell constitute the cell’s
GENOME.
-GENOME consists a single DNA molecule
or a number of DNA molecule (common
in eukaryotic cells)
- DNA molecules in a cell are packaged
into CHROMOSOMES
DISTRIBUTION OF CHROMOSOMES
DURING CELL DIVISION
-DNA is replicated and the chromosomes
condense.
-each duplicated chromosome has 2
SISTER CHROMATIDS (joined cpies of the
original chromosome) attached along
their lengths by cohesins.
-CENTROMERE is the narrow “waist” of
the duplicate chromosome, where 2
chromatids are closely attached.
-Once seperated, the chromatids are - Every eukaryotic species have different
called CHROMOSOMES chromosomes in each cells nucleus
- SOMATIC CELLS have 2 sets of
, chromosomes. during the S phase. Thus, a cell grows (G1),
- GAMETES (sperm & egg) have half as continues to grow as it copies its chromosomes
many chromosomes as somatic cells. (S), grows more as it completes preparations
for cell division (G2), and divides (M). The
-46 chromosome, 23 each parent, 22nd daughter cells may then repeat the cycle.
are AUTOSOMES, the 23rd can be X or Y
chromosome. B. MITOTIC PHASE – consists of mitosis
and cytokinesis.
PHASES OF CELL CYCLE -MITOSIS have 5 stages: Prophase (
A. INTERPHASE – cell growth and copying ->prometaphase) -> Metaphase ->
of chromosomes in preparation of cell Anaphase -> Telophase
division. -CYTOKINESES – phase of the cell cycle
-It have 3 STAGES: when the cytoplasm divide, creating 2
#1 G1 (first gap)- metabolically active-> daughter cells.
cell growth-> duplication organelles
#2 S phase (synthesis) - DNA replication
#3 G2 phase (second gap) – protein
syntheses -> large amount of ATP
produced-> replication of centrosome.
- cell grows during all 3 phases but
chromosomes are duplicated only in S
PHASE
* Prophase occupies over half of mitosis. The
nuclear membrane breaks down to form a
number of small vesicles and the nucleolus
disintegrates. A structure known as the
centrosome duplicates itself to form two
daughter centrosomes that migrate to opposite
ends of the cell. The centrosomes organize the
production of microtubules that form the
spindle fibers that constitute the mitotic
spindle. The chromosomes condense into
* Interphase can be divided into three phases: compact structures. Each replicated
the G1 phase (“first gap”), the S chromosome can now be seen to consist of two
phase (“synthesis”), and the G2 phase (“second identical chromatids (or sister chromatids) held
gap”). The G phases were misnamed as “gaps” together by a structure known as the
when they were first observed because the centromere.
cells appeared inactive, but we now know that
intense metabolic activity and growth occur THE MITOTIC SPINDLE
throughout interphase. During all three phases - Structure mase up of microtubules that
of interphase, in fact, a cell grows by producing controls chromosome movement during
proteins and cytoplasmic organelles such as
mitochondria and endoplasmic reticulum.
mitosis.
Duplication of the chromosomes, crucial for -In animal cells, assembly of spindle
eventual division of the cell, occurs entirely microtubules begins in the
-Ability of organisms to produce more of
their own kind.
-the continuity of life is based on the
reproduction of cells, or cell division.
- ASEXUAL REPRODUCTION
- GROWTH , REPAIR, & DEVELOPMENT of
eukaryotes
-TISSUE RENEWAL, CELL CYCLE
CELL DIVISION -an integral part of the cell
cycle, the life of a cell from formation to
its own division.
- Most cell division in 2 daughter cells
(MITOSIS produce 2 identical daughter
cells from the parent cell) with identical
genetic information. Exception is
MEIOSIS – special type of division that
can produce sperm and egg cells,
produce 4 daughter cells that are distinct.
CELLUL AR ORGANIZATION OF THE
GENETIC MATERIAL
- All the DNA in a cell constitute the cell’s
GENOME.
-GENOME consists a single DNA molecule
or a number of DNA molecule (common
in eukaryotic cells)
- DNA molecules in a cell are packaged
into CHROMOSOMES
DISTRIBUTION OF CHROMOSOMES
DURING CELL DIVISION
-DNA is replicated and the chromosomes
condense.
-each duplicated chromosome has 2
SISTER CHROMATIDS (joined cpies of the
original chromosome) attached along
their lengths by cohesins.
-CENTROMERE is the narrow “waist” of
the duplicate chromosome, where 2
chromatids are closely attached.
-Once seperated, the chromatids are - Every eukaryotic species have different
called CHROMOSOMES chromosomes in each cells nucleus
- SOMATIC CELLS have 2 sets of
, chromosomes. during the S phase. Thus, a cell grows (G1),
- GAMETES (sperm & egg) have half as continues to grow as it copies its chromosomes
many chromosomes as somatic cells. (S), grows more as it completes preparations
for cell division (G2), and divides (M). The
-46 chromosome, 23 each parent, 22nd daughter cells may then repeat the cycle.
are AUTOSOMES, the 23rd can be X or Y
chromosome. B. MITOTIC PHASE – consists of mitosis
and cytokinesis.
PHASES OF CELL CYCLE -MITOSIS have 5 stages: Prophase (
A. INTERPHASE – cell growth and copying ->prometaphase) -> Metaphase ->
of chromosomes in preparation of cell Anaphase -> Telophase
division. -CYTOKINESES – phase of the cell cycle
-It have 3 STAGES: when the cytoplasm divide, creating 2
#1 G1 (first gap)- metabolically active-> daughter cells.
cell growth-> duplication organelles
#2 S phase (synthesis) - DNA replication
#3 G2 phase (second gap) – protein
syntheses -> large amount of ATP
produced-> replication of centrosome.
- cell grows during all 3 phases but
chromosomes are duplicated only in S
PHASE
* Prophase occupies over half of mitosis. The
nuclear membrane breaks down to form a
number of small vesicles and the nucleolus
disintegrates. A structure known as the
centrosome duplicates itself to form two
daughter centrosomes that migrate to opposite
ends of the cell. The centrosomes organize the
production of microtubules that form the
spindle fibers that constitute the mitotic
spindle. The chromosomes condense into
* Interphase can be divided into three phases: compact structures. Each replicated
the G1 phase (“first gap”), the S chromosome can now be seen to consist of two
phase (“synthesis”), and the G2 phase (“second identical chromatids (or sister chromatids) held
gap”). The G phases were misnamed as “gaps” together by a structure known as the
when they were first observed because the centromere.
cells appeared inactive, but we now know that
intense metabolic activity and growth occur THE MITOTIC SPINDLE
throughout interphase. During all three phases - Structure mase up of microtubules that
of interphase, in fact, a cell grows by producing controls chromosome movement during
proteins and cytoplasmic organelles such as
mitochondria and endoplasmic reticulum.
mitosis.
Duplication of the chromosomes, crucial for -In animal cells, assembly of spindle
eventual division of the cell, occurs entirely microtubules begins in the
