Apoptosis and Caspases Overview

These flashcards cover key concepts regarding apoptosis, its mechanisms, caspases, and related cellular processes.

What is apoptosis?

A form of programmed cell death that is a normal and essential process for development and homeostasis.

What factor allows some cells to survive during the establishment of connections between neurons and target cells?

Survival factors released by the target cells.

What happens to the cells that do not receive survival factors?

They are eliminated by apoptosis.

What is the role of caspases in apoptosis?

Caspases are key proteins that mediate the apoptosis process.

What phenotype results from mutating caspase nine in mice?

An inability to properly undergo apoptosis, leading to abnormal cell survival.

What is the significance of apoptosis in adults?

It helps eliminate damaged or potentially harmful cells to maintain tissue health.

How do cells undergoing apoptosis appear under a differential interference contrast microscope?

They exhibit distinct characteristics that identify them as dying cells.

What is the total number of cells in the worm C. elegans?

1,090 cells, which includes exactly 131 cells that undergo apoptosis.

What process leads to an overgrowth of organs in worms?

A failure in apoptosis resulting in more than 959 surviving cells.

What are caspases classified as?

They are special protease enzymes responsible for cleaving specific proteins during apoptosis.

Explain how caspases are activated.

Caspases are synthesized as inactive precursors (pro-caspases) and activated through clustering and proteolytic cleavage.

What are initiator caspases?

Caspases that are activated early in the apoptotic process and are responsible for activating executioner caspases.

What is the extrinsic pathway of apoptosis?

A pathway induced by external signals, involving the recruitment of caspases through the death-inducing signaling complex (DISC).

What initiates the intrinsic pathway of apoptosis?

An imbalance of internal signals or stress that requires the cell to undergo apoptosis.

What role does cytochrome c play in apoptosis?

It is released from mitochondria and activates initiator caspases in the cytoplasm.

What is the purpose of phosphatidylserine exposure on apoptotic cells?

It serves as an eat-me signal to macrophages, facilitating the recognition and clearance of dying cells.

What proteins promote apoptosis by forming channels in the outer mitochondrial membrane?

Bax and Bak proteins.

What is the function of BCL-2 protein?

It inhibits apoptosis by preventing the activity of Bax and Bak.

Describe the relationship between AKT and the BCL-2 pathway.

AKT phosphorylates BAD, leading to its inactivation and allowing BCL-2 to inhibit apoptosis.

What happens to the asymmetrical distribution of phosphatidylserine during apoptosis?

It gets flipped to the outer leaflet of the plasma membrane, marking the cell for phagocytosis.

What are some morphological features of cells undergoing apoptosis?

Blebbing of the plasma membrane, fragmentation of nuclei, and condensation of chromatin.

What is the final step in the apoptosis process?

The engulfment of apoptotic cells by macrophages.

Why is it important for macrophages to recognize apoptotic cells properly?

To prevent the elimination of normal cells and avoid autoimmune responses.

What enzyme is often inhibited in apoptotic pathways leading to cell death?

Caspases.

Name a common technique used to visualize apoptosis in cells.

Fluorescent labeling of specific proteins or lipids.

What is a key structural change in apoptotic cells that aids in their clearance?

The exposure of eat-me signals on the cell surface.

How can excessive apoptosis affect an organism?

It can lead to tissue degeneration and diseases like neurodegeneration.

What is the role of lysosomes in the clearance of apoptotic cells?

They digest cellular debris during phagocytosis.

What are pro-caspases?

Inactive precursors of caspases that need to be activated for apoptosis.

How does apoptosis differ from necrosis?

Apoptosis is a controlled process of cell death, while necrosis is uncontrolled and causes inflammation.

What are executioner caspases?

Caspases that are activated by initiator caspases and carry out the final steps of apoptosis.

What cellular event do scramblases facilitate during apoptosis?

They disrupt membrane asymmetry, leading to the exposure of phosphatidylserine.

How can apoptosis research in C. elegans contribute to understanding human diseases?

It has helped identify key genes and pathways involved in programmed cell death, relevant to cancer and other diseases.

What is the apoptosis-related structure created by the binding of cytochrome c?

The apoptosome.

Name one of the main extracellular signals that can trigger apoptosis through the extrinsic pathway.

Signals from killer lymphocytes.

What technique can be used to stain apoptotic cells for visualization?

Using acridine orange to fluoresce when taken up by dying cells.

What happens to the morphology of a cell during the later stages of apoptosis?

The plasma membrane becomes permeable, leading to cellular shrinkage and blebbing.

What is the clinical relevance of understanding apoptotic mechanisms?

It can provide insights into developing therapies for diseases involving cell death dysregulation, like cancer.

How does the expression of BCL-2 affect cellular apoptosis?

Increased BCL-2 expression inhibits apoptosis and promotes cell survival.