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Know About Mesothelioma Lung
Cancer & Mesothelioma Law
Firm !
MESOTHELIOMA
The term was first used by Eastwood and Martin in 1921, to
describe the primary tumors of pleura.
WHAT IS MESOTHELIOMA CANCER?
Mesothelioma is a type of cancer that develops from the thin
layer of tissue which is known as mesothelium. It is known as
asbestos lung disease.
Mesothelium is made up of mesothelial cell which line the
chest and abdominal cavities and also the cavity around the
hearts.
The tumors found in cancer mesothelioma can be both benign and
malignant.
Malignant are called malignant mesothelioma or mesothelioma.
The types of mesothelioma are pleural mesothelioma, peritoneal
mesothelioma and pericardial mesothelioma.
CAUSES OF MALIGNANT MESOTHELIOMA
Mesothelioma is a cancer associated with large amounts of
exposure to asbestos.
There are some less common causes of mesothelioma include:
Radiation therapy.
Erionite fibers.
The DNA tumor virus SV40.
SYMPTOMS OF MESOTHELIOMA
There are some symptoms in Pleural mesothelioma.
It includes the lower back pain and shortness of breath.
Swelling in the neck or face.
High blood pressure.
Blood in sputum.
Hypertension.
Loss of weight.
Cough.
TREATMENT OF MALIGNANT MESOTHELIOMA
There is no effective treatment of mesothelioma.
A new drug Alimta was recently approved by FDA.
There may be a role for multimodality therapy using
chemotherapy and radiation therapy.
This cancer affects 2000 to 3000 Americans every year.
Mesothelioma law resources help the person who is suffering
from this disease by providing the legal resources and the
further steps of mesothelioma settlement.
This law provides detailed information on mesothelioma
diagnosis, mesothelioma law firm, mesothelioma law resources,
and more.
In this purpose there is some important role of mesothelioma
law firm.
MESOTHELIOMA LAW FIRM
Mesothelioma law firm provide an experienced lawyer to file a
lawsuit for the grant of compensation. They are dedicated to
protect the rights of affected people.
Mesothelioma law firm focus primarily on mesothelioma and
other asbestos related diseases. The victims who are suffering
a long time of the medical and financial problem associated
with asbestos related disease such as asbestos lung disease,
the law firm will handle everything regarding the law suits,
including the legal rights of the client and communicate with
witnesses for obtain medical history and more.There are so
many law firms around, but we should select the best one
depends on their performance and the past working record of
the lawyer.
https://www.youtube.com/watch?v=oCP12Jtyovg
This is the general notes on Mesothelioma, it’s symptoms and
treatments, and the mesothelioma law firm.
Thank you for reading.
The Programmed Cell Death or
Apoptosis !!
APOPTOSIS
A common form of programmed cell death. A pathway of cell
death induced by a tightly regulated suicidal program, in
which the cells destined to die active enzyme that degrade
cell own nuclear DNA and cytoplasmic proteins.
DIFFERENCE BETWEEN APOPTOSIS AND NECROSIS
There are two ways that cells die in a muticellular organism.
1. Necrosis
2. Apoptosis
NECROSIS
Cells are killed by things that harm them (such as toxic
chemicals or physical injury).a process called necrosis.
It affects group of cell.
Strong inflammatory response corresponding tissues.
Swelling of the cytoplasm and mitochondria.
Loss of plasma membrane integrity.
No energy required, passive process.
Pathologic.
APOPTOSIS
They are triggered to undergo programmed cell death.
This is known as apoptosis.
Controlled death of individual cells.
Induced by physiological stimuli.
No inflammation.
Shrinking of cytoplasm and condensation of nucleus.
Plasma membrane with no loss of integrity.
Energy (ATP) dependent. Active process.
Physiologic and pathologic.
CAUSES OF CELL DEATH
Many cells in the human body have the built in ability undergo
apoptosis. Basically, it is a general and convenient way to
remove cells that should no longer be part of the organism.
Some cells are abnormal and could hurt the rest of the
organism if they survive, such as cells with viral
infections or DNA damage.
Cells in adult organism may be eliminated to maintain
balance.
Some cells need to be deleted during development, for
instance to while an intricate structure like a hand out
of a larger block of tissue.
IMPORTANCE OF APOPTOSIS
APOPTOSIS IS A PART OF DEVELOPMENT
In many organisms programmed cell death is a normal part of
development occurs in a very predictable way.
For example, apoptosis during normal development include the
loss of a tadpole’s tail as it turns into a frog and removal
of unneeded neurons in as neural circuits in the brain are
wired.
Apoptosis plays a key role in human body. The hand started out
as a paddle like block tissue when they are in an embryo. The
block will carved into finger by apoptosis of the cells in
between the developing fingers.
This process occurs in all sorts of vertebrates species that
have finger or toe like digits and less apoptosis results in
more webbing between the digits.
ELIMINATION OF INFECTED OR CANCEROUS
CELL BY APOPTOSIS
When a cell’s DNA is damaged, it will typically detect the
damage and try to repair it. If the damage is beyond repair,
the cell will normally send itself into apoptosis. When cells
have damaged DNA but fail to undergo apoptosis, they may be on
the way to cancer.
Sometimes pre cancerous cells avoid internal apoptosis cues
are detected by immune system, which trigger apoptosis through
external signalling pathway. Successful cancerous cells manage
to duck both internal and external cues that would normally
trigger apoptosis. This allows them to divide out of control
and accumulate mutation (change in their DNA).
APOPTOSIS IN IMMUNE SYSTEM
Apoptosis plays an essential role in the development and
maintenance of a healthy immune system. When B and T cells are
first produced, they are tested to see is they react against
any of the body’s own self components. if this process fails,
self reactive cells may be released into the body, where they
can attack tissue and cause autoimmune conditions.
Apoptosis also plays an important role in allowing the immune
system to turn off its response to a pathogen. Once the
pathogen cleared from the body, the numbers of pathogen
specific immune cells are removed by apoptosis to maintain
homeostasis (balance) in the human body.
This is the general notes on Apoptosis.
Apoptotic Pathways Animated Video :
Thank you for reading.
The Cell Cycle,Cancer !!
THE CELL CYCLE AND CANCER
A disease caused by severe disruption of the mechanisms that
normally controlled the cell cycle.
DIFFERENCE BETWEEN CANCER CELL AND NORMAL
CELL
There are some differences in between cancer cell and the
normal cell. These cells behave differently than normal cell
in the body. Many of these differences are related to cell
division.
1. Cancer cell can multiply in culture without any growth
factor where as normal cells needs growth factor in
culture for multiplication.
2. Normal cell show contact inhibition. Because of this,
they form a single layer on the bottom of a culture
dish. Cancer cells, in contrast, keep dividing and pile
on top of each other in lumpy layers.
3. Normal cells divide poorly if they are floating in
liquid or soft gel, a property called anchorage
dependence. Cancer cells lose anchorage dependence and
grow fine in liquid or gel.
4. Cancer cells are called as “immortal”. They can grow and
divide in culture for long periods of time, years or
even decades. Normal cells only divide a certain number
of times in culture before they stop dividing and
eventually die.
5. Cancer cells are also different from normal cell in ways
that are not directly cell cycle related. This
difference helps them to grow, divide and form
tumors.For instance cancer cells may not undergo
programmed cell death or apoptosis, under conditions
that would trigger this process in normal cell.
6. Cancer cell also gain the ability to migrate from the
initial site of a tumor to other part of the body. This
process is known as metastasis.
CELL CYCLE REGULATORS AND CANCER
Different types of cancer involve different types of mutation
and each individual tumor has a unique genome and set of
genetic alteration. Positive regulators may be over activated
(become oncogenic) while negative regulators, also called
tumor suppressor may be inactivated.
ONCOGENES
Positive regulators that move the cell cycle forward may be
overactive cancer. A growth factor receptor may send signals
even when growth factors are not there, or a cyclin may be
expressed at abnormally high levels. These overactive forms of
genes are called oncogenes and the normal forms of genes are
called as proto oncogenes.
Mutation that turns proto oncogenes into oncogenes can take
variety of different forms. Some change the amino acid
sequence of the protein, altering its shape and trapping it in
an ‘always on’ state. Other involve amplification, in which a
cell acquires extra copies of a gene (errors in DNA
replication or repair).the extra copies of the gene result in
higher levels of protein, which drive increased or
inappropriate cell cycle progression.
Many of the proteins that transmit growth factor signals are
encoded by proto oncogenes. Normally these proteins drive cell
cycle progression only when growth factors are available. In
this simplified growth factor signalling pathway, the growth
factor receptor, the G protein Ras and the signalling enzyme
Raf are encoded by proto oncogenes. This overactive form of
proteins is commonly found in cancer cell.oncogenic Ras
mutations are found in an estimated 90% of pancreatic cancer.
TUMOR SUPPRESSORS
Negative regulators that block cell cycle progression may be
less active in cancer cells.
Tumor suppressor genes are family of normal genes that
instruct cells to produce proteins that restrains cell growth
and division. Sence,tumor suppressor genes code for proteins
that slow down cell growth and division, the loss of such
proteins allows a cell to grow and divide in an uncontrolled
fashion.
One of the most important tumor suppressors is tumor protein
p 53 , which plays a key role in the cellular response to DNA
damage. It acts primarily at the G1 checkpoint, where it blocks
cell cycle progression in response to damaged DNA and other
unfavourable conditions.
When a cell DNA is damaged, a sensor protein activates p53, which
halts the cell cycle at G1 checkpoint by triggering production
of a protein called Cdk inhibitor. This inhibitor binds to
cyclin Cdk complexes and inactivates them, preventing the cell
from moving into S phase.
If the damaged is successfully fixed, p53 will release the cell
allowing to continue through the cell cycle. If the damage is
53
not fixable, p will play a final role, triggering apoptosis
(programmed cell death) so that damaged DNA is not passed on.
When p53 is defected a cell with damaged DNA may proceed with
cell division rather than pausing the cell cycle, attempting
DNA repairs or undergoing apoptosis. The daughter cells
produced in such a division are likely to inherit mutations
due to the unpaired DNA of the mother cell. Over generation,
53
cells with faulty p tend to rapidly accumulate mutations, some
of which may convert proto oncogenes to oncogenes or inactive
other tumor suppressor and thus lead to the development of
cancer.
This is the general notes on The Cell cycle and Cancer.
The Cell Cycle and Cancer Tutorial Video
:
Thank you for reading.
Cell
Cycle
Regulation,Checkpoints,Regula
tors !!
CELL CYCLE REGULATION
Any process that controls the series of events by which a cell
goes through the cell cycle is known as the cell cycle
regulation.
During the cell cycle every cell makes a copy of its DNA and
other contents and divides in two.
There are some components in cell cycle regulatory system,
which control the cell cycle process properly. Such as,
protein called cyclins, enzyme called Cdks and a large enzyme
complex called APC/C.
CYCLINS
Cyclins are a group of related protein which are the
most important components in cell cycle regulation.
There are four types of basic cyclins found in human and
most other eukaryotes. Such as ,G1 cyclins, G1/S cyclins,S
cyclins and M cyclins.
Each cyclin associated with a particular phase,
transition or set of phases in the cell cycle and helps
drive the events of that phase or period.
Such as M cyclin promotes the M phases and helps in the
nuclear envelop breakdown and chromosome condensation.
The level of different cyclin varies considerably across
the cell cycle.
Cyclin is present at low levels for most of the cell
cycle. But increase strongly at the stage where it is
needed.
CYCLIN DEPENDENT KINASE
A cyclin must activate or inactivate many target
proteins inside of the cell. However, cyclins are not
enzymes and they do not act on directly these target
proteins by themselves. Instead they drive the event of
the cell cycle by partnering with a family of enzyme
called cyclin dependent kinase (Cdks).
Cdks are the kinases, enzyme that phosphorylate to
specific target proteins, for making it more or less
active.
For instance S cyclin sends Cdks to S phase targets
(promoting DNA replication), while M cyclin send Cdks to
M phase target (making chromosomes condense and nuclear
membrane breakdown).
In general Cdk level remains relatively constant
throughout the cell cycle, but the activity of Cdk band
the target protein changes as level of the various
cyclin rise and fall.
Cyclin and Cdks are very evolutionary conserved. That is
they are found in different types of species from yeast
to frog to human, but there are some difference in
number of different types of species.such as, yeast has
just one Cdk, while human have several that are used at
different stage of cell cycle.
MATURATION PROMOTING FACTORS (MPF)
Cyclin and Cdks works together
by a presence of factor which
promoting factor of mpf.
Like a typical cyclin M cyclin
much of the cell cycle, but
approaches the G2/M transition.
to control a cell cycle
is known as maturation
stays at low levels for
builds up as the cell
As M cyclin accumulates, bind to Cdks already present in
the cell, forming complexes that are poised to trigger M
phase.
MPF complex add phosphate tags to several different
proteins in nuclear envelops, resulting in its breakdown
and also activate target that promote chromosome
condensation and spindle assembly.
THE ANAPHASE PROMOTING COMPLEX/CYCLOSOME
(APC/C)
In addition to driving the events of M phase, MPF also
triggers its own destruction by activating the anaphase
promoting complex/cyclosome.
A protein complex that causes M cyclins to be destroyed
starting in anaphase.
The destruction of M cyclin pushes the cell out of
mitosis, allowing the new daughter cell to enter G1.
The APC/C plays a key role in separation of sister
chromatid in metaphase.
First it add a ubiquitin tags to a protein called
securin (regulatory protein), sending it for recycling.
When securin is sent for recycling, separase becomes
active which chops up the cohesin that holds sister
chromatids together, allowing them to separate.
CHECKPOINT AND REGULATION
Cdks, cyclins and the APC/C are the direct regulators of cell
cycle, they response the cues from inside or outside the cell.
Positive cues like growth factor typically increase activity
of Cdks and cyclins, while negative ones, like DNA damage,
typically decrease or block activity.
Thus cell must be able to deal with this damage, fixing it if
possible and preventing cell division if not.
Key to the DNA damage response is a protein called p 53 , a
famous tumour suppressor often called as ‘the guardian of the
genome’. p53 works on multiple levels to ensure that cells do
not pass on their damaged DNA through cell division.
ROLE OF p53 IN CELL CYCLE REGULATION
p53 stops the cell cycle at G1 checkpoint by triggering by
production of kinase inhibitor. Then it binds to the
Cdk-cyclin complex and blocks their activity.
Then it activates the DNA repair enzyme and p 53
will
release the cell, allowing it to continue through the
cell cycle.
If the DNA damage is not fixable, p53 will play a final
role, triggering apoptosis (programmed cell death) so
the damaged DNA is not passes on.
All three of these roles help p 5 3 prevent cancer. Cancer
typically arises through a series of mutations that lead to
uncontrolled cell division. Cell do not divide when DNA is
damaged, p 53 prevents mutations (changes in DNA) from being
passed on to daughter cells, potentially leading to cancer.
Cell Cycle Checkpoints Tutorial Video :
This is the general notes on Cell cycle Regulation.
Thank you for reading.
Cell Cycle Checkpoints !!
CELL CYCLE CHECKPOINTS
The cell cycle has regulatory points called checkpoint.
A check point is one of several points in the eukaryotic cell
cycle at which the progression of a cell to the next stage in
the cell cycle can be halted until conditions are favourable
(e.g. the DNA is repaired).
These checkpoints occur near the end of G 1 at the G2 or the M
transition during metaphase.
There are a number of checkpoints, but the three most
important ones, which are given below:
1. The G1 checkpoint, at the G1/S transition.
2. The G2 checkpoint, at the G2/M transition.
3. The spindle checkpoint, at the transition from metaphase
to anaphase.
G1 CHECKPOINT
The G 1 checkpoint, also called start in yeast and the
restriction point in animals, is the main decision point
for a cell.
This is the primary point at which it must choose
whether or not to divide.
Once the cell passes the G1 checkpoint and enter S phase,
it becomes committed to division, by copying its DNA.
G1 checkpoint will continue the rest of the way through
the cell cycle and produce two daughter cells.
Before entering S phase there are some factors a cell might
assess:
Size: Is the cell large enough to divide?
Nutrients: Are all nutrients present in the environment?
Molecular Signals: Is the cell receiving positive cues
(such as growth factors) from neighbors?
Mechanical Signals: Is the cell attached to a support?
DNA Integrity: Is any of the DNA damaged?
If a cell does not get the go ahead at the G 1 checkpoint, it
may enter a resting state called G phase. Many cell types
spend most of their existence in this phase, carrying out
their mature functions in the body.
Some cells that enter G phase, such as nurons, will never reenter the cell cycle under normal circumstances. Other such as
liver cells, may start dividing again if conditions are right
(e.g. if the liver cell is injured and must be repaired)
G2 CHECKPOINT
Once a cell passes the G1 checkpoint, it is committed to
divide; it begins to replicate its DNA, an irreversible
step on the path to mitosis.
To make sure that cell division goes smoothly, the cell
has an additional checkpoint before the onset of M
phase, called the G2
At this stage the cell is mostly concerned with the condition
of its DNA, and will primarily check:
DNA Integrity: Is any of the DNA damaged?
DNA Replication: Was the DNA completely copied during S
phase?
If error or damaged are detected, the cell will pause at the G2
checkpoint to allow for repair.
METAPHASE CHECKPOINT
The mitotic spindle checkpoint occurs during metaphase.
Once a cell enter M phase, it will start to split its
duplicate chromosomes, evenly and accurately between its
two daughter cells.
Cell must make sure that the chromosomes are properly
positioned and ready to separate before it leaves
metaphase.
At the spindle checkpoint or M phase checkpoint the cell
confirms:
Alignment: All of the chromosomes are lined up at the
metaphase.
Tension: each chromosome is under tension from the
spindle, that is two kinetochores are attached to
microtubules from opposite poles.
Cell Cycle Tutorial Video :
This is the general notes on Cell Cycle Checkpoint.
Thank you for reading.
Introduction
Of
Cycle,It’s Phases In
Cell
Cell
Cycle !!
CELL CYCLE
The cell cycle is the repetitive pattern of growth and
division that occurs in the eukaryotic cells
The cell division cycle is a vital process by which a single
celled fertilized egg develops into a mature organism, as well
as the process by which hair, skin, blood cells and some
internal organs are renewed.
PHASES OF CELL CYCLE
The eukaryotic cell cycle consists of two basic stages.
Interphase
Mitosis
INTERPHASE
After cell division each of the daughter cells begins the
interphase of a new cell cycle.
Interphase is the phase of cell cycle in which the cell spends
the majority of its time for preparing for cell division.
There are some stages in interphase of cell cycle.
1. Gap 0/ G
A resting phase where the cell has left the cycle and
has stopped dividing.
2. Gap 1/G1
First growth stage after cell division.
It is the post mitotic phase.
Cell matures by making by more cytoplasm and organelles.
Cell carries on its normal metabolic activities.
G1 checkpoint control mechanism ensures that everything
is ready for DNA synthesis.
3. Synthesis/s phase
It is the synthesis phase.
During this phase duplication of DNA and centriole takes
places.
The duplication of DNA results in the duplication of
chromosomes.
4. Gap 2/ G2
It is the second growth stage.
It is the pre mitotic gap phase.
The synthesis of RNA and proteins continue in this
phase.
All cell structures needed for division are made (e.g.
centrioles).
The G 2 checkpoint control mechanisms ensure that
everything is ready to enter the M (mitosis) phase and
divide.
MITOSIS
It is the division of the nucleus. It is also called as
occurs in eukaryotes.
only
There are some stages in mitosis.
1. Prophase
Chromatin in nucleus condenses to form visible
chromosomes.
Mitotic spindle forms from fiber of centrioles.
Nuclear membrane and nucleolus are broken down.
Spindle fiber attached to the centromere of each
chromosome.
Eventually, spindle extends between two opposite pole of
the cell.
2. Metaphase
Chromosomes, attached to the spindle fibers, move to the
center of the cell.
The chromosomes line up across the center of the cell.
3. Anaphase
The sister chromatid separated into individual
chromosomes.
The chromosomes continue to move until they have
separated into two groups.
4. Telophase
Sister chromatid at opposite poles.
Spindle disassembles.
Nuclear envelop forms around each set
chromatid.
Nucleolus reappears.
Eventually, the mitotic spindle breaks up.
of
sister
5. Cytokinesis
Cytokinesis means the division of cytoplasm.
Division of cell into two identical daughter cell.
In plant cells, cell plate forms at the equator to
divide cell.
In animal cells, cleavage furrow forms to split cell.
This is the general idea about Cell Cycle and It’s Phases in
Cell Cycle.
Thank You.
Meiosis,It’s Stages In Cell
Division !!
MEIOSIS
Meiosis is a part of cell division. It is a specialized type
of cell division that reduces the chromosome number by half.
This process occurs in all sexually reproducing single celled
and multicellular eukaryotes, including animals, plants and
fungi.
STAGES OF MEIOSIS
In meiosis cell division, DNA
replication is followed by two
rounds of cell division to
produce four potential daughter
cells, each with half the number
of chromosomes as the original
parent cell. The two meiotic
divisions are known as Meiosis I
and Meiosis II.
The first meiotic division is similar to mitosis cell division
and the second meiotic division is the ‘reduction’ stage. This
differs slightly according to whether male and female gametes
are to be produced. They are repeated during both meiosis I
and meiosis II.
The period of time meiosis I and meiosis II is called
interkinesis.No replication of DNA occurs during
interkinesis.because, the DNA is already duplicated.
MEIOSIS I
Prophase
1. Prophase is typically the longest phase in meiosis cell
division.
2. Chromosomes condense and become visible.
3. Spindle fiber emerges from the centrosomes.
4. Nuclear envelop breaks down.
5. Centrosomes move toward opposite poles.
Metaphase
1. Chromosomes are lined up across the center of the cell.
2. Each sister chromatid is attached to a spindle fiber
originating from a opposite poles.
Anaphase
1. Centrosomes split into two.
2. Sister chromatids (now chromosomes) are pulled towards
opposite poles.
3. Certain spindle fiber begins to elongate the cell.
Telophase
1. Chromosomes arrive at opposite poles and begin to
decondense.
2. Nuclear envelop material surrounds each set of
chromosomes.
3. The meiotic spindle breaks down.
4. Spindle fiber continues to push poles apart.
Cytokinesis
Cytokinesis usually occurs simultaneously, forming two haploid
daughter cells.
In animal cells, a cleavage furrow separates the daughter
cells.
In plant cells, a cell plate, the precursor to a new cell
wall, separates the daughter cells.
No chromosomes replication occurs between the end of meiosis I
and the begin of meiosis II, because the chromosomes are
already replicated.
MEIOSIS II
1. The phases of meiosis II are all exactly identical to
meiosis I.
2. The only difference is that they are occurring in two
cells at the same time.
3. The end product is four,non identical, haploid cells.
SIGNIFICANCE OF MEIOSIS
1. Meiosis reduces the number of chromosomes in each cell
so that sexual reproduction is possible.
2. Meiosis insures that every sperm and egg ever made will
be a little bit difference.
3. Species with more variation have a greater chance for
survival.
This is the general notes on Meiosis Cell Division and It’s
Stages.
Thank You.
Mitosis,It’s Stages In Cell
Division !!
MITOSIS
Mitosis is a part of a cell division. It is defined as the
type of cell division by which a single cell divides in such
way as to produce two genetically identical daughter cell.
STAGES OF MITOSIS
The process of mitosis is divided into stages corresponding to
the completion of one set of activities and the start of the
next.
Stages are described below
Prophase
1. Prophase is the first and longest phase of mitosis.
2. Early in the prophase stage the chromatin fibers shorten
into chromosomes that are visible under a light
microscope.
3. Later in prophase, the nucleus disappears, the nuclear
envelop break down, and the two centrosomes begin to
form the mitotic spindle of microtubules.
4. As the microtubules extend in the length between the
centrosomes, centrosomes are pushed to opposite ‘poles’.
5. Eventually, the spindle extends between two opposite
pole of the cell.
Metaphase
1. The second phase of mitosis is metaphase.
2. The chromosomes line up across the center of the cell.
3. Microtubules connect the centromere of each chromosome
to the poles of the spindle.
Anaphase
1. Anaphase is the third phase of mitosis.
2. The sister chromatids separate into
chromosomes.
individual
3. The chromosomes continue to move until they have
separated into two groups.
Telophase
1. Telophase is the fourth and final stage of mitosis.
2. It begins after the chromosomal movement stops.
3. Chromosomes gather at the opposite end of cell and lose
their distinct shape.
4. A new nuclear envelop formed around each chromatin mass.
5. Nucleoli appear.
6. Eventually the mitotic spindle breaks up.
Then the cytoplasm begins to divide around the two new
nucleoli.
Cytokinesis
Cytokinesis is the process by which the cytoplasm of original
cell forms the two new (‘daughter’) cells aground the two new
(‘daughter’) nuclei formed by the process of mitosis.
In the case of animal cell, a cleavage furrow forms around the
cell equator then constricts as a ring until it cuts
completely through the cell.
In plants cytoplasm is divided by a cell plate being formed.
After the completion of cytokinesis it begins the next ‘cell
cycle’.
SIGNIFICANCE OF MITOSIS
1. Mitosis ensures that each new body cell has the same
genetic makeup as its parents. Mutation can and do occur
occasionally but, for the most part all o your body cell
have identical DNA.
2. Mitosis not only functions to replace cells and make new
cells (growth) it also reduces cell size.
3. Preserve continuity of life.
4. Important in unlocking the mysteries of the embryonic
development and stem cells.
5. Important in understanding how cancer develops and could
someday provide clues in stopping cancer.
This is the general notes on Mitosis Cell Division and It’s
Stages.
Thank You.
Introduction
of
Division,It’s Types !!
Cell
The cell is the basic structural, functional and biological
unit of all known living organisms.
CELL DIVISION
Cell division is the process by which a cell, called parent
cell, devides into two cells, called daughter cell. It occurs
as a part of cell cycle in eukaryotes.
When the cell devides, everything inside the cell also
devided.The nucleus, the chromosomes, the mitochondria divided
also.
Prokaryotes undergo a vegetative cell division known as binary
fission, where their genetic material is segregated equally
into two daughter cell.
For simple example such as amoeba (unicellular organisms), one
cell division is equivalent to reproduction, an entire new
organism is created.
TYPES OF CELL DIVISION
There are two distinct type of cell division.
1.
Mitosis
In multicellular the somatic (body cell) cells undergo
mitosis.
Mitosis is the type of cell division by which a single
cell divides in such a way as to produce two genetically
identical ‘daughter cells’.
This is the method by which the body produces new cells
for both growth and repair of again or damaged tissues
throughout the body.
2.
Meiosis
In multicellular organisms the germ cells (cell destined
to become sperm eggs) divided by a related process
called meiosis.
Meiosis which is also referred to as ‘reproduction
division’ is the form of cell division in which a cell
divides into four ‘daughter cells’.
Each daughter cell has half of the number of chromosomes
of the parent cell or original cell.
Meiosis occurs prior to the formation of sperm (in male)
and ova (in female).
The cells return to having the normal (called ‘diploid’)
number of chromosomes after fertilization of the ova by
sperm.
Meiosis consists of two successive divisions, each of which is
divided into four phases. The first meiotic division is
similar to mitosis and the second meiotic division is the
‘reduction’ stage.
Meiosis enables the exchange of genetic material between
chromosomes.
PURPOSE OF CELL DIVISION
Cell division for reproduction creates offspring with
traits from both mother and father.
Cell division for growth and repair creates exact copies
of cell.
This is the Introduction of Cell Division and It’s Types.
Thank You.
Centrosome & Centrioles,It’s
Structure,Function !!
CENTROSOME
In cell biology, the centrosome (Latin centrum ‘center’ and
Greek soma ‘body’) is an organelle that serves as the main
microtubule organizing center (MTOC) of the animal cell. It
regulates the cell division cycle.
The centrosome was discovered by Edourad Van Beneden in 1883
and was described and named in 1888 by Theodor Boveri.
STRUCTURE OF CENTROSOME
Centrosomes are composed of two orthogonally arranged
centrioles surrounded by an amorphous mass of protein
termed the pericentriolar material (PCM).the PCM
contains proteins responsible for microtubules
nucleation and anchoring.
In general each centriole of the centrosome is based on
nine triplet microtubule assembled in a cartwheel
structure and contains centrin, connexion and tektin.
FUNCTION OF CENTROSOME
Centrosomes are associated with the nuclear membrane
during prophase of the cell cycle. In mitosis the
nuclear membrane breaks down and the centrosome
nucleated microtubules can interact with the chromosome
to build the mitotic spindle.
The mother centriole, the older of the two in the
centriole pair, also has a central role in making cilia
and flagella.
The centrosome replicates during the S phase of the cell
cycle. During the prophase in mitosis, the centrosomes
migrate to opposite poles of the cell. The mitotic
spindle then forms between two centrosome. Upon
divisions, each daughter cell receives one centrosome.
In the absence of the centrioles the microtubules of the
spindle are focused by motors allowing the formation of
a bipolar spindle.
Aberrant numbers of centrosomes in a cell have been
associated with cancer.
CENTRIOLES
In animal cells have two organelles known as centrioles.
The centrioles play a major role in cell division. In animal
cells the centrioles plays a major role in cell division but
in the plant cells have the ability to reproduce even without
the centrioles.
STRUCTURE OF CENTRIOLES
The centrioles are cylindrical shaped cellular
organelles. They are found in most eukaryotic cells.
The centrioles are made of groups of microtubules.
These microtubules are arranged in a in a pattern of
9+3.
The pattern of the microtubules for a ring of 9
microtubules known as “triplets” and microtubules are
arranged at right angles to one another.
Each triplet fibers are composed of three sub fibers or
sub tubules. The sub tubules are made up of protein
tubulin.
All the structure that surrounds the centrioles together
constitutes the centriole satellite. The number of these
satellites varies.
FUNCTIONS OF CENTRIOLES
In higher animal cells centrioles form mitotic poles.
The centrioles functions as the microtubules organizing
center. It is important event in major cellular process
that is cell division and flagella formation.
The centrioles pair duplicates within a cell and the two
pairs migrate to the opposite ends of the cell to
organize the mitotic spindle or spindle fibers.
Each centriole gives rise to a new centriole. The
centrioles that are newly formed remain tightly attached
to the parent centriole and it elongates during the S
and G2 phase.
In the prophase stage the centrioles pairs start moving
towards the opposite poles of cell, and also forms the
spindle fibers simultaneously.
The migration of the positioning of the centrioles
determines the orientation of the spindle. It also
influences the chromosomes attachment to the spindle
fibers.
The spindle fibers are responsible for the segregation
of chromosomes into the daughter cells.
At the end of each cell cycle, the cell has two
centrioles. One the mother centriole and the other newly
formed centriole which is the daughter centriole.
The centrioles may produce flagella or cilia.
The fiber of the tail of sperms also arises from the
centrioles.
This is the general notes on Centrosome and Centriole.
Thank You.