Cell division mitosis

Mr. Lakhan Singh
Msc Nursing 1st Year
Kbtnc Bhopal

LearningObjectives
• The cell cycle and its phases.
• Features of somatic cell division.
• The cell division “mitosis”.
• The resting (G0) post mitotic phase
• The cytokinesis phase

Key Words
Bayan Al-Ghadeer DalalAl-Anazi
• Chromosome
• chromatin
• centriole & centrosome
• centromere & kinetochore
• chromatid

CHROMOSOME
Chromosome is a threadlike structure of nucleic
acids and protein found in the nucleus of most
living cells, carrying genetic information in the
form of genes.

chromatin
Chromatin is essentially the substance of
chromosomes. It is made up of DNA attached to
a protein structure, together with chromosomal
RNA.

Centriole & centrosome
A centriole is a barrel microtubule structure. Two
centrioles arrange themselves perpendicularly to
form a centrosome.

centromere &kinetochore
• The centromere is constricted region of the
chromosomes that holds the sister chromatids
together, the site where kinetochore forms.
• The kinetochore is a complex protein
containing structure to which microtubules
attach.

chromatid
Chromatid is a one strand
of the chromosome after it
has duplicated for cellular
division. The two
chromatids are called
“sister chromatids” and
will eventually split and
move to opposite ends of
the cell.
Sister chromatids

Ready?
Let’s begin

Cell division
The cell cycle or cell division is the series of events
that take place in a cell leading to its division and
multiplication. Without cell division, an organism’s
cell would not regenerate, resulting in not only cell
death but also the death of the entire organism

• Define cell cycle:- the cell cycle is the
sequence of growth and division of a cell. It
consists of three major phases:
O Interphase
O Mitosis
O Cytokinesis.
Cell division

Resting G0 phase
The term “post-mitotic” is sometimes used to refer to both
quiescent and declining cells. Non proliferative cells in
multicellular eukaryotes generally enter the quiescent G0
state from G1 and may remain quiescent for long periods of
time.

Interphase
Estimated (90% of cycle)
3 phases
•G1 phase
•S phase
•G2 phase

• The first phase within interphase, from the end of
the previous M phase until the beginning of DNA
synthesis called G1 (G indicating Gap).
• It is also called the growth phase.
• This phase is marked by synthesis of various
enzymes that are required in S phase, mainly those
needed for DNA replication.
• Duration of G1 is highly variable, even among
different cells of the same species.
G1 phase

S phase
 The S phase starts when DNA synthesis, when it is
complete, all of the chromosomes have been
replicated. E.g. each chromosomes has two (sister)
chromatids
During this phase, the amount of DNA in the cell has
effectively doubled
Rate of RNA transcription and protein synthesis are
very low during this phase.

• Cell continues to grow and if a problem occurs
in DNA replication, it will be repaired.
• Cell will prepare for mitosis.
• Cell synthesizes proteins needed for cell
division
G2 phase

Estimated (10% of cycle)
Includes 2 parts :
1)Mitosis
•Prophase
•Promataphase
•Metaphase
•Anaphase
•Telophase
2) Cytokinesis
M phase

Mitosis
• Mitosis is the process in which a eukaryotic
cell separates the chromosomes in its cell
nucleus, into two identical sets in two
daughter cells.

• It occurs only in somatic cells.
• It ensures sustenance of life.
• The daughter cells carry number of
chromosomes as parents cell.
• Equal distribution of genetic material
• It is also known as equational division
Features of mitosis division

Prophase
•
Duration (15 min)
Chromosomes condense (get
thicker) and coil, they become
visible under light microscope.
• The two sister chromatids of each
chromosomes attach at a point
called centromere.
• Spindle fibers begin to form from
two centrosome, and they will start
moving apart.

•
Duration (15 min)
The nuclear membrane
disappears.
• Kinetochores will get attached
to the centromere.
• The spindle fibers become
attached to the kinetochore.
Prometaphase

•
Duration (20 min)
Chromosomes reach their most
highly condensed state.
• The spindle fibers begin to
contract to the centromeres of
the chromosomes, which are
now arranged along the middle
of the spindle.
Metaphase

•
Duration (3 min)
The centromere of each
chromosome splits, allowing the
sister chromatids to separate.
• The chromatids are then pulled by
the spindle fibers toward opposite
sides of the cell.
• The two sets of chromosomes are
identical.
Anaphase:

•
Duration (10 min)
New nuclear membranes are formed
around each of the two sets of 46
chromosomes.
• The spindle fibers disappear.
• Chromosomes become thinner.
•
•
Cytoplasm starts dividing by contractile
ring.
At the end, we will have two diploid
daughter cells, which are identical.
Telophase:

Cytokinesis
• The division of the cytoplasm and organelles
Begin in anaphase and completed by the end of telophase
.
This is the last stage of mitosis. It is the process of splitting
the daughter cells apart.
Each daughter cells contains the same number and same
quality of chromosomes.

Summary
• Interphase (90% of cycle)
o G1 phase~ growth
o S phase~ synthesis of DNA
o G2 phase~ preparation for
cell division
• Mitotic phase (10% of cycle)
o Mitosis~ nuclear division
o Cytokinesis~ cytoplasm
division

Cell division mitosis

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Cell division mitosis

Similar to Cell division mitosis (20)

Recently uploaded

Recently uploaded (20)

Cell division mitosis