apoptosis

Examples of apoptosis in the following topics:

• Programmed Cell Death

  • Apoptosis is the process of PCD that may occur in multicellular organisms.
  • Apoptosis can also be initiated via external signaling.
  • Apoptosis is also essential for normal embryological development.
  • It is hypothesized that necroptosis can serve as a cell-death backup to apoptosis when the apoptosis signaling is blocked by endogenous or exogenous factors, such as viruses or mutations.
  • This video describes the process of apoptosis, or programmed cell death.

• Cell Signaling and Cell Death

  • When a cell is damaged, unnecessary, or dangerous to an organism, a cell can initiate the mechanism for cell death known as apoptosis.
  • External signaling can also initiate apoptosis.
  • Another example of external signaling that leads to apoptosis occurs in T-cell development.
  • Apoptosis is also essential for normal embryological development.
  • A cell signaling mechanism triggers apoptosis, which destroys the cells between the developing digits.

• Tumor Suppressor Genes

  • At this point, a functional p53 will deem the cell unsalvageable and trigger programmed cell death (apoptosis).
  • The damaged version of p53 found in cancer cells, however, cannot trigger apoptosis.
  • If repairs are unsuccessful, p53 signals apoptosis.
  • A cell with an abnormal p53 protein cannot repair damaged DNA and cannot signal apoptosis.

• Immunological Memory

  • As the infection is cleared and pathogenic stimuli subside, the effector cells are no longer needed; they undergo apoptosis.

• Immunodeficiency

  • During the acute phase, HIV-induced cell lysis and killing of infected cells by cytotoxic T cells accounts for CD4+ T cell depletion, although apoptosis (programmed cell death) may also be a factor.

• Natural Killer Cells

  • A granzyme, a protease that digests cellular proteins, induces the target cell to undergo programmed cell death, or apoptosis.

• Plant Life Spans

  • Even as some parts of a plant, such as regions containing meristematic tissue (the area of active plant growth consisting of undifferentiated cells capable of cell division) continue to grow, some parts undergo programmed cell death (apoptosis).

• Regulator Molecules of the Cell Cycle

  • If the DNA cannot be repaired, p53 can trigger apoptosis (cell suicide) to prevent the duplication of damaged chromosomes.

• Steps of Virus Infections

  • Some infected cells, such as those infected by the common cold virus known as rhinovirus, die through lysis (bursting) or apoptosis (programmed cell death or "cell suicide"), releasing all progeny virions at once.

• Animal Viruses

  • On the other hand, non-enveloped viral progeny, such as rhinoviruses, accumulate in infected cells until there is a signal for lysis or apoptosis, and all virions are released together.