Fate of a Cell Flashcards

Flashcards covering the vocabulary and mechanisms regarding the fate of a cell, including apoptosis, necrosis, autophagy, and senescence.

Apoptosis

A form of programmed cell death in animals, from the Greek word meaning 'falling off,' used to eliminate unwanted cells through an intracellular death program.

Necrosis

An unprogrammed or accidental form of cell death that occurs in response to acute hypoxic or ischemic injury, characterized by cell swelling and bursting.

Autophagy

From the Greek word 'autóphagos' meaning self-devouring; a fundamental catabolic mechanism where cells degrade dysfunctional or unnecessary components via lysosomes.

Senescence

A cellular program, from the Latin word 'senex' (growing old), involving an irreversible arrest in cell division that restricts the proliferation of damaged cells.

Pyknosis

Nuclear compaction observed during the process of cellular death or distress.

Karyorrhexis

Fragmentation of the cell nucleus following pyknosis during cell death.

Blebbing

The development of irregular bulges on the surface of a cell as it shrinks and condenses during apoptosis.

Caspases

A family of proteases responsible for the molecular machinery of apoptosis, synthesized as inactive precursors called procaspases.

Initiator caspases

Caspases that cleave and activate downstream executioner caspases to trigger an amplifying proteolytic cascade.

Executioner caspases

Caspases that dismember key cellular proteins, such as nuclear lamins, causing irreversible breakdown of cellular structures.

Bcl2 family

A group of intracellular proteins that regulate apoptosis; some members promote caspase activation while others, like Bcl2 itself, inhibit it.

Bax and Bak

Death-inducing Bcl2 family members that are activated by DNA damage to promote the release of cytochrome c from mitochondria.

Cytochrome c

An electron-transport protein released from the mitochondrial intermembrane space into the cytosol to activate initiator procaspases.

Apoptosome

A large, seven-armed, pinwheel-like protein complex that recruits and activates initiator pro-caspase-9 following the release of cytochrome c.

Extrinsic pathway

An apoptotic pathway triggered by extracellular signals activating cell-surface receptor proteins known as death receptors.

Intrinsic pathway

A mitochondria-dependent apoptotic pathway triggered by internal signals following damage from radiation, toxins, or free radicals.

Fas

A death receptor present on the surface of many mammalian cells that is activated by Fas ligand on killer lymphocytes to induce apoptosis.

Survival factors

Extracellular signal proteins that promote cell survival by suppressing apoptosis.

Mitogens

Extracellular signal proteins that stimulate cell division by overcoming intracellular brakes that block cell cycle progression.

Growth factors

Extracellular signal proteins that stimulate an increase in cell size and mass by promoting protein synthesis and inhibiting degradation.

HMGB1

High mobility group box 1; a damage-associated molecular-pattern (DAMP) molecule released during necrosis that activates innate immune cells.

Macroautophagy

A form of autophagy in which a double membrane structure called an autophagosome envelops cargo and fuses with a lysosome.

Microautophagy

A form of autophagy where the lysosomal membrane itself invaginates to engulf cellular cargo for degradation.

Chaperone-mediated autophagy (CMA)

A form of autophagy where heat-shock cognate proteins deliver specific substrates to lysosomes.

Omegasomes

Specialized cup-shaped, ER-associated structures where the nucleation of the phagophore membrane begins during autophagy.

mTOR

Mechanistic target of rapamycin; a kinase involved in nutrient sensing that acts as a negative regulator of autophagy.

AMPK

AMP-activated protein kinase; a serine/threonine kinase that senses low cellular energy (ATP) levels and induces autophagy by activating the Atg1/ULK1 complex.