Cell Biology: Apoptosis and Cancer Overview

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Questions and Answers

What is a key characteristic of apoptosis as it relates to the cell nucleus?

The nucleus expands and divides

The nucleus merges with the cytoplasm

The nucleus remains unchanged

The nucleus condenses and fragments (correct)

Which of the following correctly describes caspases?

Effectors of cell division

Enzymes activated by other proteins during apoptosis (correct)

Proteins involved in immune response

Inactive compounds that promote cell survival

What happens to the cytoplasm during the process of apoptosis?

It condenses and fragments into apoptotic bodies (correct)

It swells and merges with other cells

It remains stable and unchanged

It becomes proliferative and grows

Which apoptotic pathway is triggered by external signals?

Extrinsic pathway Signup and view all the answers

Which of the following is a biochemical change that occurs during apoptosis?

Caspase activation Signup and view all the answers

Which type of cell death is characterized by an immune response and can be induced by various stimuli?

Immunogenic cell death Signup and view all the answers

What cellular process involves programmed cell death that is crucial for maintaining tissue homeostasis?

Apoptosis Signup and view all the answers

What is the relationship between mutations in genes and the development of cancer?

Most cancers result from mutations in somatic and germline cells Signup and view all the answers

Which of the following statements accurately describes oncogenes?

They promote cell proliferation and survival when activated Signup and view all the answers

Which process is not typically associated with programmed cell death?

Necrosis Signup and view all the answers

What is a key morphological characteristic of apoptosis compared to necrosis?

Cellular condensation Signup and view all the answers

Which statement is true regarding the cellular membrane integrity in apoptosis and necrosis?

Membranes remain intact in apoptosis Signup and view all the answers

What drives the process of apoptosis regarding cellular signals?

Increased levels of oxidants Signup and view all the answers

Which of the following events is NOT associated with necrosis?

Phagocytosis by immune cells Signup and view all the answers

In apoptosis, how is DNA typically fragmented?

Ladder-like pattern Signup and view all the answers

What happens to the cell during necrosis in terms of ATP?

ATP is depleted Signup and view all the answers

Which of the following statements best describes the tissue impact of apoptosis compared to necrosis?

Individual cells are affected in apoptosis Signup and view all the answers

Which signal is likely to promote cell survival rather than apoptosis?

Presence of Il-2 Signup and view all the answers

What is the primary role of caspases in cellular processes?

Initiate apoptotic proteolytic cleavage Signup and view all the answers

What is required for caspase activation?

Proteolytic cleavage and removal of prodomain Signup and view all the answers

What is the primary function of tumor suppressor genes?

Inhibiting cell proliferation Signup and view all the answers

Which pathway is categorized as extrinsic in apoptosis?

Death receptor mediated pathway Signup and view all the answers

What happens when there is a disruption or deletion of the p53 gene?

Uncontrolled cell proliferation can occur Signup and view all the answers

Which ligand is matched correctly with its receptor?

TRAIL with DR4 Signup and view all the answers

Which of the following genes is associated with retinoblastoma?

Rb1 Signup and view all the answers

What is the role of p21 in relation to p53?

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

What effect does ligand-induced trimerization have on death receptors?

It induces proximity of Caspase 8 Signup and view all the answers

Which of the following is NOT a consequence of mutated oncogenes?

Promotion of programmed cell death Signup and view all the answers

What is Apaf1's role in the intrinsic apoptotic pathway?

It serves as an adaptor molecule for procaspase activation Signup and view all the answers

What is a common disorder associated with the DCC gene?

Colorectal cancer Signup and view all the answers

Which method is suitable for detecting apoptotic changes in DNA?

TUNEL staining for DNA fragmentation Signup and view all the answers

Which molecule is a death effector in the apoptosis signaling pathway?

Caspase 8 Signup and view all the answers

Which one of the following genes is implicated in lung cancer on a sporadic basis?

WT1 Signup and view all the answers

Which factor is involved in regulating programmed cell death?

Apoptotic signals Signup and view all the answers

What role does apoptosis play in adult physiology?

Facilitates DNA damage repair Signup and view all the answers

What distinguishes necroptosis from traditional necrotic cell death?

Necroptosis is a regulated process involving specific kinases Signup and view all the answers

In what context does autophagy mainly exert cytoprotective functions?

In response to stress Signup and view all the answers

What is a consequence of inhibiting autophagy during developmental processes?

Accelerates cell death Signup and view all the answers

Which of the following diseases is associated with excess apoptosis?

Neurodegenerative diseases Signup and view all the answers

What is the main characteristic of autophagic cell death?

Massive cytoplasmic vacuolization Signup and view all the answers

What is a primary outcome of necroptosis in cells?

Rapid plasma membrane permeabilization Signup and view all the answers

What happens when TNFalpha-mediated necrosis is inhibited?

It leads to necroptosis Signup and view all the answers

Study Notes

Cell Death & Apoptosis

Cell death is a crucial process for maintaining a constant number of cells in the body.
Two major forms of cell death are apoptosis (programmed cell death) and necrosis (cell death, via injury).
Apoptosis is a controlled, tightly regulated process that removes cells without damaging surrounding tissues.
Necrosis is an uncontrolled process triggered by cell injury/damage and leads to inflammation.
Apoptosis is a very common process during embryo development.
Embryo development involves programmed cell death to mold and refine the shape.
The tail of the tadpole is absorbed via apoptosis.
In adult multicellular organisms, billions of cells are lost via apoptosis each hour. Most of these cells do not have defects and are removed based on the controls of regulation and development.

Apoptosis Objectives

Understand the various types of cell death pathways.
Assess methods to assess cell death.
Understand the physiological processes of apoptosis.
Analyze how defects in apoptotic pathways relate to diseases.

Types of Cell Death

Apoptosis = programmed cell death (suicide)
Necrosis = cell killing/decay/destruction

Morphological Apoptosis Changes

Changes in cell morphology during apoptosis:
- Cell shrinkage
- Chromatin condensation
- Nuclear fragmentation
- Formation of apoptotic bodies
- Phagocytosis of apoptotic bodies

Biochemical Changes in Apoptosis

Caspase activation (enzymatic proteases).
Endonuclease activation.

Caspases

Enzymatic proteins (proteases) that degrade other proteins.
Made as inactive precursors (procaspases).
Activation occurs upon receiving specific signals.
A single caspase can cleave lamin proteins, causing breakdown of the nuclear membrane.

Caspase Functions and Structure

Proteolytic cleavage activates caspases.
Prodomain and linker region are removed.
Large and small subunits form an active enzyme complex.
Two heterodimers interact to form a tetramer with catalytic sites.
Caspase family contains over 14 members.

Apoptotic Pathways

Extrinsic (death receptor) pathway
- Signals via death receptors.
- These receptors induce activation of caspase-8, leading to apoptosis.
Intrinsic (mitochondrial) pathway
- Signals from inside the cell.
- Release of cytochrome c from mitochondria triggers caspase-9 activation and apoptosis.

Ligand/Death-Induced Cell Death

Ligands and receptors involved in cell death. Examples provided in chart format for Ligands, FasL, TNF,TRAIL and Receptors, Fas (CD95), TNF-R, DR4 (Trail-R).

Cancer & Apoptosis

Evasion of apoptosis can lead to uncontrolled cell growth.
Activating apoptosis in cancer cells has potential as a treatment method.
Cancer is a genetic disease.
- Occurring via mutations in genes. This results in altered proteins during cell division.
Cancer originates from mutations in somatic or germline cells.

Genes Playing a Role in Cancer Development

Oncogenes
Tumor suppressor genes
DNA repair genes

Functions of Proto-Oncogenes

Secreted growth factors.
Growth factor receptors
Cytoplasmic signal transduction proteins
Nuclear proteins; regulating transcription
Cell growth genes

Oncogenes

Mutated proto-oncogenes.
Always activated.
Constantly stimulate proliferation.
Example: mutated ras gene, always active

Tumor Suppressor Genes

Normal function is inhibiting cell proliferation to guard against uncontrolled cell growth.
Absence/inactivation leads to increased cancer risks (leading to uncontrolled cell growth).
Example: p53, BRCA1, BRCA2

p53 Tumor Suppressor Gene

Activated by DNA damage.
Triggers cell cycle arrest or apoptosis.
Inactivation is associated with cancer.
p53 phosphorylated; activates p21 gene causing arrest of cell cycle to allow time for DNA repair.

Cancer Treatment Therapies

Various methods for cancer treatment. Diagram displays the major pathways.

Promising Cancer Targets

HERCEPTIN
STI-571

Apoptosis: Programmed Cell Death

(True/False) In adult tissues, cell death balances cell division.
Apoptosis involves controlled self-destruction to prevent damage to neighboring cells.
Signals from within and external sources trigger apoptosis.
Cellular components like caspases and mitochondria are key players in the apoptotic process.
Distinction between mitogens, growth factors and survival factors.
Apoptosis occurs during a specific portion of the cell cycle.
Telomeres and telomerase impact cell aging/death.
Specific cell types in the body are designed to divide, grow, or both.

Autophagic Cell Death

Autophagy is a self-eating process that takes place in both healthy and diseased cells.
Autophagy can play a protective or destructive role during stress reactions.

Necroptosis

Necroptosis is a form of necrotic cell death, considered programmed or regulated.
Discovery of the RIP1 kinase inhibitor as necroptosis-inhibiting; lead to recognition of necroptosis in cell death pathways.
Necroptosis is a programmed necrotic cellular death pathway.

Other Cell Death Classifications

Other kinds of cell death pathways exist (such as ferroptosis, lysozomal cell death, mitotic cell death, pyroptosis, etc.)

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Description

This quiz explores the key characteristics of apoptosis, including its relationship with the cell nucleus and the role of caspases. Additionally, it delves into how apoptosis is linked to cancer development and the distinctions between various types of cell death. Test your knowledge on these crucial aspects of cell biology!