The Purpose of Cell Death and Digestion

What is the main purpose of cell death?

To remove damaged, infected, or unnecessary cells and maintain tissue homeostasis

What type of balance does cell death help maintain?

Balance between cell death and proliferation

What are the two main types of cell death?

Apoptosis and necrosis

Is apoptosis energy dependent?

Yes

Is necrosis energy dependent?

No

Which type of cell death causes inflammation?

Necrosis

Which type of cell death is typically non-inflammatory?

Apoptosis

What protein family regulates mitochondrial apoptosis?

Bcl-2 family

What is the key pro-apoptotic transcription factor activated by DNA damage?

p53

What mitochondrial proteins are activated by p53 to initiate apoptosis?

Bax and Bak

What anti-apoptotic proteins are inhibited by p53?

Bcl-2 and Bcl-XL

What happens after Bax and Bak insert into the mitochondrial membrane?

Cytochrome c is released

What does cytochrome c activate?

Caspase cascade

What are examples of executioner caspases?

Caspase-3 and caspase-8

What is the primary trigger for extrinsic apoptosis?

Binding of death ligands like TNF-alpha or Fas ligand to death receptors

What are the death receptors involved in extrinsic apoptosis?

TNFRs (Tumor Necrosis Factor Receptors)

What proteins form pores in the target cell membrane during immune-mediated apoptosis?

Perforin

What proteins enter through pores to activate apoptosis?

Granzymes

What surface signal allows phagocytes to recognize apoptotic cells?

Flipped phosphatidylserine

What is necroptosis?

A programmed, lytic form of inflammatory cell death

What is pyroptosis?

A form of inflammatory cell death triggered by infections

What is ferroptosis?

Iron-dependent cell death involving oxidative stress

What can TNF binding to TNFR1 lead to?

Inflammation, lytic cell death, or barrier damage

What are DAMPs?

Damage-associated molecular patterns released by dying cells

What is the process of engulfing dying cells called?

Phagocytosis

What does NADPH oxidase generate during phagocytosis?

Reactive oxygen species (ROS)

What does the phagosome fuse with to form a phagolysosome?

Lysosome

What is the purpose of the phagolysosome?

To digest the contents of the engulfed cell

What is autophagy?

Self-digestion of cellular debris and organelles

What is heterophagy?

Digestion of external material taken up by phagocytosis

What are the three types of autophagy?

Microautophagy, macroautophagy, and chaperone-mediated autophagy

What happens in microautophagy?

Lysosome folds inward to engulf cellular material

What happens in macroautophagy?

Autophagosome forms and fuses with lysosome

What does chaperone-mediated autophagy do?

Shuttles proteins across the lysosomal membrane for digestion

How does autophagy contribute to immunity?

By delivering intracellular pathogens and antigens for degradation and presentation

What receptor is triggered by viral RNA during autophagy?

TLR7

What does TLR7 activation lead to?

Type I interferon production