Apoptosis and Its Roles in Development

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Questions and Answers

Which process is primarily responsible for the removal of cells during the development of the tadpole's tail?

Mitosis

Necrosis

Autophagy

Apoptosis (correct)

Approximately how many cells are lost through apoptosis in the human body each hour?

Trillions

Millions

Thousands

Billions (correct)

Which of the following is NOT a characteristic of apoptosis?

Cell shrinkage

DNA fragmentation into 200 bp units

Induction of an immune response (correct)

Cytochrome c release from the mitochondria

What crucial role does apoptosis play in the immune system's development and maintenance?

Removing immune cells that don't pass certain tests Signup and view all the answers

How does apoptosis differ from necrosis in terms of cellular impact?

Apoptosis is a clean cell death, whereas necrosis causes cell lysis and inflammation Signup and view all the answers

Which cellular process is characterized by cellular condensation and intact cell membranes?

Apoptosis Signup and view all the answers

What is a key distinction regarding energy requirements between apoptosis and necrosis?

Apoptosis requires ATP, necrosis depletes it Signup and view all the answers

How does the pattern of DNA fragmentation differ between apoptosis and necrosis?

Apoptosis shows ladder-like fragmentation, necrosis shows random fragmentation Signup and view all the answers

What is the typical tissue response to apoptosis, compared to necrosis?

Apoptosis is followed by phagocytosis without inflammation, necrosis causes an inflammatory reaction Signup and view all the answers

Which of the following is a typical consequence of necrosis?

Inflammation of surrounding tissue Signup and view all the answers

What is the role of phagocytes in programmed cell death?

They engulf apoptotic cell remains Signup and view all the answers

Which of these is associated with triggering apoptosis?

Exposure to UV light Signup and view all the answers

What is the initial step in apoptosis after the pathway has been activated?

The actual 'suicide' of the cell Signup and view all the answers

Which cellular process, when reduced, can contribute to the development of cancer?

Apoptosis Signup and view all the answers

What is the primary underlying cause of cancer at a molecular level?

Mutations in genes leading to altered proteins Signup and view all the answers

Which of the following is NOT a primary type of gene implicated in cancer development?

Histone modifying genes Signup and view all the answers

What distinct trigger is required for apoptosis in cardiac myocytes during ischemia specifically, versus during reperfusion injury?

Distinct initiator caspases Signup and view all the answers

In ischemia/reperfusion injury, which cell type undergoes apoptosis first?

Endothelial cells Signup and view all the answers

Which of the following is NOT a typical role of apoptosis in adult organisms?

Neurodevelopment Signup and view all the answers

What is a key characteristic of necroptosis that distinguishes it from traditional necrotic cell death?

It is regulated by RIP1 and RIP3 kinases. Signup and view all the answers

In the context of stress-induced autophagy, what is most commonly observed?

It is a cytoprotective mechanism that promotes homeostasis and survival Signup and view all the answers

Which of the following best describes the double-membraned vesicles involved in autophagy?

Autophagosomes Signup and view all the answers

What is a key feature of cell death by necroptosis?

It involves rapid plasma membrane permeabilization and release of DAMPs Signup and view all the answers

Which of these conditions is typically associated with deficient apoptosis?

Autoimmunity Signup and view all the answers

What is a key difference between the roles of autophagy in developmental contexts versus a stress response?

Autophagy is protective in stress and can be lethal in some developmental settings Signup and view all the answers

Which condition is NOT typically linked to necroptosis?

Autoimmunity Signup and view all the answers

What is the primary function of tumor suppressor genes?

To inhibit cell proliferation, acting as a brake on cell division Signup and view all the answers

Which of the following processes is directly triggered by the phosphorylation of the p53 protein?

Cell cycle arrest and DNA repair Signup and view all the answers

What is the consequence of a disruption or deletion of the p53 gene?

Uncorrected DNA damage and uncontrolled cell proliferation Signup and view all the answers

A mutation that leads to a constantly activated ras protein would be considered what type of gene?

An oncogene Signup and view all the answers

What is the role of the p21 gene in the context of p53 activation?

To induce cell cycle arrest for DNA repair Signup and view all the answers

Which of the following is NOT a gene associated with a hereditary cancer syndrome, according to the text?

DCC Signup and view all the answers

What is a key characteristic of apoptosis that distinguishes it from necrosis?

The cell destroys itself from within, avoiding leakage Signup and view all the answers

Which genes are primarily involved in transcriptional regulation, based on the text?

WT1, Rb1 and p53 Signup and view all the answers

What is the primary mechanism by which caspases are activated?

Through proteolytic cleavage Signup and view all the answers

Which of the following is NOT a typical characteristic of caspase activation?

Inhibition of catalytic sites Signup and view all the answers

Which pathway is typically associated with death receptor-mediated apoptosis?

The extrinsic pathway Signup and view all the answers

Which of the following ligands is known to activate the Fas receptor?

FasL Signup and view all the answers

What is the role of 'death domains' in apoptosis?

They trigger caspase activation following receptor trimerization Signup and view all the answers

In the intrinsic apoptotic pathway, what role does cytochrome c play?

It is released from the mitochondria and helps activate Caspase 9 as part of the apoptosome complex Signup and view all the answers

What technique is used to detect DNA fragmentation during apoptosis, by tagging DNA strand breaks?

TUNEL staining Signup and view all the answers

Which of the following is NOT typically used to directly assess caspase activity?

Nuclear morphology assessment Signup and view all the answers

Study Notes

Cell Death & Apoptosis Overview

Cell death is crucial for maintaining a constant number of cells.
Two main forms: apoptosis (programmed cell death) and necrosis (killing/decay).
Apoptosis is a controlled process, avoiding damage to surrounding cells.
Necrosis is uncontrolled, causing cell leakage and inflammation.

Apoptosis in Development & Diseases

Apoptotic cell death is a common process during embryonic development.
In adult multicellular organisms, billions of healthy cells are lost via apoptosis every hour.
Apoptosis is crucial for development and regulation, eliminating cells that don't meet criteria.
Defects in apoptotic pathways can lead to diseases.

Apoptosis Objectives

Understanding cell death pathways is a key objective.
Determining how to assess cell death is also important.
The physiological aspects of apoptosis need to be understood.
How defects in apoptotic pathways correlate with diseases is another aspect.

Types of Cell Death: Apoptosis vs. Necrosis

Apoptosis is programmed cell death.
Necrosis is cell death due to injury.
Apoptosis is a tidy process with no inflammation.
Necrosis is messy involving inflammation and damage to surrounding cells.

Apoptosis Morphology and Biochemistry

Morphological changes in apoptosis involve cell shrinkage, chromatin condensation, and apoptotic body formation.
Biochemical changes in apoptosis include caspase activation and endonuclease activation.

Apoptosis Pathways

Two main pathways regulate cell death: intrinsic and extrinsic.
Extrinsic pathway utilizes death receptors and signals.
Intrinsic pathway involves mitochondrial events and signals.

Identifying and Assessing Apoptosis

Several methods can identify apoptotic cells.
Techniques include nuclear staining, DNA fragmentation detection (TUNEL staining), and single-cell electrophoresis (Comet assay).

Apoptotic Changes and Processes

Caspases - crucial protease enzymes in apoptosis, breaking down cellular components to tidy up.
Genes playing roles in cancer development include oncogenes, tumor suppressor genes, and DNA repair genes

Importance of Apoptosis

Essential for normal physiology and development
Critical for processes like immune system maturation and neural development in adults.
Plays a role in processes like immune privilege and wound repair.
Excess apoptosis can lead to diseases like neurodegenerative disorders and cardiac infarction.
Insufficient apoptosis can lead to diseases like cancer and autoimmunity.

Other Forms of Cell Death

Autophagy - a cellular process where cells recycle their own components
Necroptosis – a programmed form of necrotic cell death
Other forms of cell death exist in normal and pathological conditions.

Cancer and Apoptosis

Evasion of apoptosis is a common feature of cancer cells, allowing uncontrolled cell growth.
Activating apoptosis in cancer cells is a promising area of cancer treatment.
Cancer is a genetic disease with mutations driving uncontrolled cell proliferation.

Cancer Treatment/Therapies

Treatments aim to target specific molecules or pathways crucial for excessive cell growth.

Promising Cancer Targets

Several cellular regulators and signaling components (e.g. HER2 and STI-571) are promising cancer treatment targets.

Apoptosis and Cell Death

Apoptosis and cell death are related but distinct processes.
In apoptosis, the cell actively destroys itself, while necrosis is often due to injury.

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Description

This quiz explores the process of apoptosis, particularly in the context of tadpole tail development and its crucial role in the immune system. It contrasts apoptosis with necrosis, discussing cellular impacts and energy requirements. Test your understanding of the features and implications of programmed cell death.