Molecular Basis of Cell Death

Flashcards covering the definitions, morphological features, biochemical changes, and laboratory methods used to study the molecular basis of cell death, with a focus on apoptosis.

Apoptosis

A process of cell death that occurs physiologically during the elimination of unnecessary cells or tissues, or induced by external factors such as cytostatic drugs.

Caspases

Intracellular proteolytic enzymes that, when activated, lead to DNA degradation, damage to protein structures, and cell disintegration.

Bcl-2 proteins

A family of proteins that regulate the intrinsic pathway of apoptosis by acting as either promoters or inhibitors.

Chromatin condensation

A morphological change in apoptotic cells involving the loss of microscopically recognizable nuclear structures.

Apoptotic bodies

Small fragments formed during cell disintegration that are subsequently removed via phagocytosis by macrophages.

Cytochrome c

A molecule released from the mitochondria into the cytoplasm during the intrinsic pathway of apoptosis.

DNA laddering

A characteristic image in agarose gel electrophoresis representing DNA fragments of low molecular weight, specifically multiples of $180\,bp$.

Comets assay

An electrophoresis technique where apoptotic cells show a "tail" of degraded DNA and a "head" containing high molecular weight fragments remaining in the cell.

TUNEL method

An in situ identification method for DNA fragmentation that uses terminal deoxynucleotidyl transferase (TdT) to bind fluorochrome-conjugated deoxynucleotides.

Phosphatidylserine

A phospholipid located on the cytosolic side of the membrane in living cells that transfers to the extracellular side during early apoptosis.

Annexin V

A protein used in flow cytometry to detect the presence of phosphatidylserine on the surface of the cell membrane.

Propidium iodide (PI)

A dye that binds to DNA only if it can penetrate the loosened membrane of dead or late apoptotic cells, often used concurrently with Annexin V.

JC-1

A carbocyanine dye that forms orange fluorescing aggregates in mitochondria with high potential but disintegrates into green fluorescing monomers when potential decreases.

PARP (Poly ADP-Ribose Polymerase)

A protein whose $89\,kDa$ fragment is used as a marker to detect the activation of executive caspase 3.

Necroptosis and pyroptosis

Specific examples of types of cell death that are distinct from standard apoptosis and necrosis.