Apoptosis

What are tissues composed of?

Cells and extracellular matrix.

What are the basic requirements for all tissues?

Mechanical support, innervation, and means for respiration, nutrition, and waste disposal.

What are the three factors that contribute to tissue stability?

Cell communication, selective cell-cell adhesion, and cell memory.

What is cell communication in tissues?

Each cell type monitors the environment and adjusts its behavior based on received signals.

What role do adhesion molecules play in tissues?

They govern selective cell-cell adhesion, which is crucial for tissue structure.

What is cell memory in the context of tissues?

Specialized patterns of gene expression from embryonic development are maintained stably.

What type of mutations primarily lead to cancer?

Somatic mutations, which are non-germ line mutations.

What is an oncogene?

A mutant form of a normal gene that can promote cancer, such as a mutated proto-oncogene.

What is the function of tumor suppressor genes?

They regulate the cell cycle and prevent uncontrolled cell growth.

What is the difference between necrosis and apoptosis?

Necrosis is uncontrolled cell death with inflammation; apoptosis is programmed cell death without inflammation.

What occurs during necrosis?

Cellular swelling, membrane rupture, and an inflammatory reaction.

What occurs during apoptosis?

Cell shrinkage, organelle reduction, and phagocytosis by macrophages.

Why is apoptosis important for development?

It is necessary for processes like embryonic morphogenesis and the formation of proper connections between neurons.

What triggers a cell to undergo apoptosis?

Withdrawal of positive signals and receipt of negative signals.

What are some examples of positive signals for cell survival?

Growth factors for neurons and interleukin-2 (IL-2).

What are some negative signals that can induce apoptosis?

Increased oxidants, DNA damage, and death activators like TNF-α.

What is the role of caspases in apoptosis?

They are effector proteins that execute the death program in cells.

What is the apoptotic pathway?

A series of signals and proteins that lead to programmed cell death.

What is the effect of hypoxia on cells?

It can trigger apoptosis due to lack of oxygen.

How does loss of adhesion affect cells?

It can trigger apoptosis as cells lose their connection to the extracellular matrix.

What is the significance of mitochondrial leakage in apoptosis?

It indicates the release of cytochrome c, which activates caspases.

What is the outcome of DNA fragmentation during apoptosis?

It leads to organized cell death without inflammation.

How does apoptosis help regulate cell number?

By eliminating damaged, infected, or unnecessary cells.

What is apoptosis?

A programmed cell death process that is essential for maintaining cellular homeostasis.

What are the two main pathways of apoptosis?

Extrinsic pathway and intrinsic pathway.

What initiates the extrinsic pathway of apoptosis?

Death ligands binding to death receptors.

Which initiator caspase is involved in the extrinsic pathway?

Caspase 8.

What is the role of effector caspase 3?

It executes the death program by cleaving key cellular proteins.

What triggers the intrinsic pathway of apoptosis?

DNA damage and mitochondrial signals.

Which initiator caspase is involved in the intrinsic pathway?

Caspase 9.

What is the role of cytochrome C in apoptosis?

It is released from mitochondria to activate the apoptosome and initiator caspases.

What does the term 'MOMP' stand for?

Mitochondrial Outer Membrane Permeabilization.

What is the function of the Bcl-2 family in apoptosis?

They regulate mitochondrial signals and determine whether apoptosis occurs.

What are pro-apoptotic factors?

Factors that promote apoptosis by inducing MOMP and releasing cytochrome C.

What is the function of IAP family proteins?

They inhibit caspase activity and prevent apoptosis.

What happens during the execution phase of apoptosis?

Executioner caspases cleave substrates leading to cell shrinkage and fragmentation.

What is the role of adaptor proteins in the extrinsic pathway?

They facilitate the aggregation of death receptors and recruitment of initiator procaspases.

What is the outcome of caspase activation?

It leads to the cleavage of proteins responsible for cell death.

What is the significance of the death-inducing signaling complex?

It is formed when death receptors aggregate, leading to the activation of initiator caspases.

What is the end result of apoptosis?

The cell is engulfed by macrophages or neighboring cells without causing inflammation.

What is the physiological role of apoptosis?

To eliminate damaged or unnecessary cells in a controlled manner.

What are executioner caspases responsible for?

They cleave cellular proteins, leading to the morphological changes associated with apoptosis.

How does the intrinsic pathway differ from the extrinsic pathway?

The intrinsic pathway is activated by internal signals like DNA damage, while the extrinsic pathway is triggered by external death signals.

What is the role of p53 in apoptosis?

It activates the intrinsic pathway in response to DNA damage.

What is the final step in the apoptosis process?

Degradation of cellular components and engulfment by phagocytes.

What is the role of the Bcl-2 family of proteins?

They regulate the intrinsic pathway of apoptosis.

What triggers the release of cytochrome c from mitochondria?

Pro-apoptotic proteins stimulate its release.

What is the function of Apaf-1 in apoptosis?

It aggregates initiator procaspases when cytochrome c binds to it.

How do survival factors affect apoptosis?

They suppress apoptosis by regulating Bcl-2 proteins.

What are BH123 pro-apoptotic proteins?

Proteins that stimulate the release of cytochrome c and are required for the intrinsic pathway.

What is the role of anti-apoptotic Bcl-2 family proteins?

They bind to and inhibit pro-apoptotic proteins, promoting cell survival.

What activates BH3-only pro-apoptotic proteins?

Apoptotic stimuli such as deprivation of survival factors or p53 response to DNA damage.

Name some pro-apoptotic BH3-only proteins.

Bad, Bid, Bik, Bim, Bmf, Hrk, Noxa, and Puma.

What is the mechanism by which survival factors inhibit apoptosis?

They activate signaling pathways that suppress the cell death program.

What happens when cells are deprived of survival factors?

They activate the programmed cell death pathway.

What are mitogens?

Secreted signal proteins that stimulate cell division by overcoming cell cycle brakes.

What is the role of growth factors in cellular processes?

They stimulate growth by promoting synthesis and inhibiting degradation of macromolecules.

What is the function of Rb protein in cell cycle control?

It inhibits cell cycle progression by binding to E2F.

What is the consequence of malfunctioning apoptosis?

It can lead to diseases such as cancer, neurodegenerative diseases, and autoimmune diseases.

What are the effects of too much apoptosis?

Tissue atrophy, neurodegeneration, and thin skin.

What are the consequences of too little apoptosis?

Hyperplasia, cancer, and atherosclerosis.

How does apoptosis relate to neurodegenerative diseases?

Neuronal death can result from loss of connections, growth factors, or damage.

What role does p53 play in apoptosis?

It is a transcription factor that prevents tumorigenesis by initiating the intrinsic cell death pathway.

What is the significance of the extrinsic death receptor pathway?

It regulates immune cell function and development by inducing apoptosis.

What are rationally designed compounds targeting in cancer therapy?

They specifically target intrinsic or extrinsic cell death regulators.

What is the apoptosome?

A complex formed by Apaf-1 and cytochrome c that activates caspase-9.

What happens when caspase-9 is activated?

It activates other caspases, leading to a cascade that destroys cytoplasmic proteins and degrades DNA.

What is the last step of apoptosis?

Phagocytosis of the cell.

Tissues are composed of cells and ________.

extracellular matrix

All tissues require mechanical support, ________, and means for respiration, nutrition, and waste disposal.

innervation

The three factors contributing to tissue stability are cell communication, selective cell-cell adhesion, and ________.

cell memory

Cell communication involves each cell type monitoring the environment and adjusting its behavior based on ________.

received signals

Selective cell-cell adhesion is governed by different ________ molecules.

adhesion

Cell memory refers to specialized patterns of gene expression from ________ development that are stably maintained.

embryonic

Cancers primarily develop through the accumulation of ________ mutations.

somatic

An ________ is a mutant form of a normal gene that can promote cancer.

oncogene

Mutations in genes that control ________ can lead to diseases like neurodegeneration.

apoptosis

Mutations in ________ can lead to metastasis by affecting cell adhesion.

E-cadherin and Integrins

Cell death by injury can be caused by mechanical damage or exposure to ________ chemicals.

toxic

Cell death by suicide can be triggered by internal or ________ signals.

external

In necrosis, cellular ________ occurs, and membranes remain intact.

condensation

Necrosis requires ________ for its processes.

ATP

Necrosis results in cell lysis, eliciting an ________ reaction.

inflammatory

DNA fragmentation in necrosis is typically ________.

random or smeared

In apoptosis, ________ is required, and membranes remain intact.

ATP

Apoptosis results in the cell being ________, with no tissue reaction.

phagocytosed

Apoptosis exhibits ________ DNA fragmentation.

ladder-like

In contrast to apoptosis, necrosis causes cellular ________.

swelling

Necrotic cells lyse, leading to an ________ response.

inflammatory

Apoptosis is described as a ________ process of cell death.

programmed

Morphological changes in apoptosis include cell shrinkage, membrane blebbing, organelle reduction, and ________ condensation.

chromatin

Apoptotic cells are typically engulfed by ________.

macrophages

Apoptosis is crucial for proper development, such as embryonic ________.

morphogenesis

Apoptosis is necessary for the sloughing off of the inner lining of the ________.

uterus

Most cells die if they fail to receive ________ signals from other cells.

survival

Apoptosis is needed to destroy cells infected with ________.

viruses

A cell might commit apoptosis due to withdrawal of positive signals, such as ________ for neurons.

growth factors

Receipt of negative signals, like increased levels of ________ within the cell, can induce apoptosis.

oxidants

Tumor necrosis factor alpha (TNF-α) is an example of a ________ that can induce apoptosis.

death activator

The apoptotic pathway involves triggers, modulators, effectors, and ________.

substrates