Apoptosis Its purpose What if apoptosis stop? Necrosis vs Apoptosis Morphology of Apoptosis Pathways of Apoptosis

1. APOPTOSIS(PROGRAMMED CELL
DEATH)
SUBMITTED TO DR. RAZIA NOREEN
SUBMITTED BY ISMA ZULFIQAR

2. WHAT IS APOPTOSIS?
• The cells of a multicellular organism are members of a highly organized community.
The number of cells in this community is tightly regulated—not simply by controlling
the rate of cell division, but also by controlling the rate of cell death.
• If cells are no longer needed, they commit suicide by activating an intracellular death
program. This process is therefore called programmed cell death, although it is more
commonly called apoptosis (from a Greek word meaning “falling off,” as leaves from a
tree).
• The amount of apoptosis that occurs in developing and adult animal tissues can be
astonishing.

3. Purpose of apoptosis
• In a healthy adult human, billions of cells die in the bone marrow and intestine every
hour. It seems remarkably wasteful for so many cells to die, especially as the vast
majority are perfectly healthy at the time, they kill themselves. What purposes does this
massive cell death serve?
• Apoptosis, programmed cell death, serves as a regulatory role in multicellular organisms
for the purpose of maintaining cellular integrity, determining embryological outcomes,
and for getting rid of aged cells.
• Roughly 50 billion cells undergo apoptosis each day in humans.

4. • In some cases, the answers are clear. Mouse paws, for example, are
sculpted by cell death during embryonic development, they start out as
spade like structures, and the individual digits separate only as the cells
between them die.

5. • In other cases, cells die when the structure they form is no longer needed.
When a tadpole changes into a frog, the cells in the tail die, and the tail,
which is not needed in the frog, disappears.

6. • In many other cases, cell death helps regulate cell numbers. In the
developing nervous system, for example, cell death adjusts the number of
nerve cells to match the number of target cells that require innervation. In
all these cases, the cells die by apoptosis.
• If a cell has become badly stressed or damaged, it may commit apoptosis to
prevent itself from becoming dangerous to the organism as a whole.

7. WHAT IF APOPTOSIS STOP?
• When apoptosis doesn't happen, it results in cancer. So apoptosis is a
normal process, and the absence of apoptosis, can lead to cancer.
• Too much apoptosis in an otherwise normal human being will result in a
number of so-called neurodegenerative diseases where cells die when
they're not supposed to die. And they get messages from some place, most
of which we don't understand, to tell them to die, so in a certain part of the
lower part of the brain, that's what causes Parkinson's disease. This also
characterizes Huntington's disease, Alzheimer's disease and a number of
other neurodegenerative diseases.

8. NECROSIS VS. APOPTOSIS
• Cells that die as a result of acute injury typically swell and burst. They
spill their contents all over their neighbors, a process called cell necrosis
causing a potentially damaging inflammatory response.
• By contrast, a cell that undergoes apoptosis dies neatly, without damaging
its neighbors. In apoptosis;
1. The cell shrinks and condenses.
2. The cytoskeleton collapses, the nuclear envelope disassembles, and
the nuclear DNA breaks up into fragments.

9. • Most importantly, the cell surface is altered, displaying properties that cause the
dying cell to be rapidly phagocytosed, either by a neighboring cell or by a
macrophage before any leakage of its contents occurs.
• This not only avoids the damaging consequences of cell necrosis but also allows the
organic components of the dead cell to be recycled by the cell that ingests it.
Necrotic
cell
Apoptotic
cell

10. MORPHOLOGY OF APOPTOSIS

11. APOPTOSIS PATHWAY
• There are two major types of apoptosis pathways, each of which illustrates
an important point about how apoptosis is triggered and why it is useful.
1. Extrinsic Pathway
2. Intrinsic Pathway

13. INHIBITION OF APOPTOSIS
• A short list of potential methods of anti-apoptotic therapy includes
1. Stimulation of the IAP (inhibitors of apoptosis proteins) family of
proteins,
2. Caspase inhibition,
3. PARP inhibition,
4. Inhibition of Bcl-2 proteins.

14. WHAT IS
ANGIOGENESIS?
• From the Greek word
Angêion, meaning vessel,
the formation of blood
vessels from existing
vasculature.

15. WHAT IS
NEUROGENESIS?
• Neurogenesis is the process by which new
neurons are formed in the brain.
Neurogenesis is crucial when an embryo is
developing, but also continues in certain
brain regions after birth and throughout
our lifespan.