Apoptosis and Necrosis: Pathways, Mechanisms, and Cell Removal

Caspases

Enzymes that play a key role in the process of apoptosis

Necrosis

Uncontrolled cell death where the cell bursts open and infects other cells

Endocytosis

Process where the plasma membrane folds to engulf a source and forms a new plasma membrane

Signaling molecules in extrinsic pathway

Molecules that bind with death receptors to initiate apoptosis

Macrophages

Cells that remove apoptotic bodies via endocytosis

Apoptosis

Programmed cell death

Intrinsic pathway

Mitochondrial pathway that detects internal damage and activates caspases

Extrinsic pathway

Death receptor pathway activated by signaling molecules binding with death receptors

Steps of intrinsic pathway

1. Internal damage detected by mitochondria; 2. Mitochondria activate caspases; 3. Caspases damage nuclear proteins, plasma membrane, DNA; 4. Caspases break down cytoskeleton and nuclear membrane; 5. Cell shrinks and blebs into apoptotic body; 6. Macrophages remove apoptotic body via endocytosis

Steps of extrinsic pathway

1. Signaling molecules bind with death receptor; 2. Death receptors activate caspases; 3. Caspases damage nuclear proteins, plasma membrane, DNA; 4. Caspases break down nuclear membrane and cytoskeleton; 5. Cell shrinks and blebs into apoptotic bodies; 6. Macrophages remove apoptotic body via endocytosis

Cell cycle checkpoints

Mechanisms that detect internal damage in the cell

Blebbing

The process where a cell shrinks and forms protrusions during apoptosis

Key structures damaged by caspases

Plasma membrane, DNA, nuclear proteins

Cytoskeleton breakdown

Process where caspases dismantle the cytoskeleton during apoptosis

Apoptotic body

The structure formed when a cell undergoes apoptosis and shrinks

Internal inflammation in necrosis

Causes the cell to burst open and affect surrounding cells

Role of mitochondria in apoptosis

Detects internal damage and activates the cascade of caspases

Cascade of caspases

A series of enzymatic reactions activated during apoptosis

Cell signal in apoptosis

The initial signal that triggers the activation of caspases

Nuclear membrane breakdown

A step in apoptosis where caspases dismantle the nuclear membrane

Plasma membrane folding

The process during endocytosis where the membrane engulfs a source

Source in endocytosis

The material or particle that is taken into the cell via endocytosis