9.2 Controlling Cell Numbers - Apoptosis

A set of vocabulary flashcards covering the molecular mechanisms, triggers, and developmental roles of apoptosis as described in the MCB2011 lecture by Professor Helen Abud.

Apoptosis

An active, regulated process of programmed cell death, also known as "cell suicide," used for development and tissue maintenance.

Tissue Homeostasis

The maintenance of a perfect balance between cell production (division) and cell death.

Syndactyly

A human mutation characterized by a lack of cell death between digits, resulting in fused fingers or toes.

BMP4

A secreted signaling protein that activates the apoptotic pathway to remove webbing between digits in developing chick embryos.

Necrosis

Cell death induced by tissue injury where cells swell and burst, releasing intracellular contents and causing damaging inflammation.

Apoptotic body

Small, membrane-bound fragments of a cell produced during the later stages of apoptosis before being engulfed by phagocytic cells.

p53

A protein that, when stabilized by high levels of Myc or DNA damage, activates transcription of pro-apoptotic BH3-only proteins like PUMA and NOXA.

Caspases

A family of intracellular proteases that mediate the proteolytic cascade to trigger and execute apoptosis.

CAD (Caspase-Activated DNase)

An endonuclease that, once freed from its inhibitor iCAD by caspases, cleaves the cell's DNA.

Extrinsic pathway

An apoptotic pathway initiated by extracellular signals, such as the activation of the Fas receptor on a target cell by lymphocytes.

Intrinsic pathway

An apoptotic pathway triggered by internal stimuli, such as DNA damage, which depends on the release of cytochrome C from the mitochondria.

Cytochrome C

A component of the mitochondrial electron-transport chain that, when released into the cytosol, helps activate the intrinsic apoptotic pathway.

Apoptosome

A multi-protein complex composed of Apaf1 and cytochrome C that recruits and activates caspase-9.

C. elegans

A nematode used to identify apoptosis genes, where exactly 131 of its 1090 somatic cells undergo programmed cell death during development.

Bcl2 family proteins

A group of proteins divided into three classes (anti-apoptotic, pro-apoptotic effectors, and pro-apoptotic BH3-only proteins) that regulate apoptosis.

Bax and Bak

Pro-apoptotic effector Bcl2 family proteins that aggregate in the outer mitochondrial membrane to release cytochrome C.

BH3-only proteins

Pro-apoptotic proteins such as Bad, Bim, Bid, Puma, and Noxa that interact with and inhibit anti-apoptotic Bcl2 proteins.

Trophic factors

Extracellular survival signals, such as neurotrophins, that suppress the default state of apoptosis in many cell types.

$$Ca^{2+}$$

Changes in the intracellular concentration of this ion can act as a trigger for apoptosis.

Akt kinase

A kinase activated by trophic factors that phosphorylates Bad, inhibiting its pro-apoptotic activity and promoting cell survival.