Neuroscience Apoptosis and Neurodegeneration Quiz
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Questions and Answers

What do the 'DAMAGE' and 'Physiological death signals' lines in the diagram represent?

  • Triggers for apoptosis (correct)
  • Forms of cellular energy
  • Methods of cell repair
  • Types of cell division

What does the tilted seesaw in the diagram illustrate?

  • The relationship between energy production and cell death
  • The differentiation of stem cells
  • The rate of cellular respiration
  • The balance between proapoptotic and antiapoptotic signals (correct)

Why is apoptosis considered essential for the well-being of an organism?

  • It increases cell proliferation rates
  • It stimulates tissue regeneration
  • It enhances metabolic processes
  • It helps maintain cellular homeostasis (correct)

In the context of the diagram, what do proapoptotic proteins do?

<p>Stimulate the process of apoptosis (C)</p> Signup and view all the answers

What does the term 'homeostasis' refer to in relation to apoptosis?

<p>The balance of proapoptotic and antiapoptotic signals (B)</p> Signup and view all the answers

Which factor is not involved in neuronal death?

<p>Overproduction of nerve growth factor (B)</p> Signup and view all the answers

What does synaptosis refer to in the context of neuronal damage?

<p>Loss of synapses that may be reversible (A)</p> Signup and view all the answers

Which of the following brain regions is primarily affected by selective apoptosis in neurodegeneration?

<p>Cerebral cortex (D)</p> Signup and view all the answers

What role does oxidative stress (ROS damage) play in neuronal function?

<p>It leads to neuronal dysfunction and loss. (A)</p> Signup and view all the answers

Which of the following diseases is associated with neuronal death in the context of neurodegenerative disorders?

<p>Alzheimer's disease (D)</p> Signup and view all the answers

What is one of the first observable changes in a cell undergoing apoptosis?

<p>The cell loses cell contacts and changes shape. (B)</p> Signup and view all the answers

What occurs to the chromatin during the apoptotic process?

<p>Chromatin condenses and moves towards the nuclear envelope. (C)</p> Signup and view all the answers

What leads to significant cell shrinkage during apoptosis?

<p>Loss of cellular water. (B)</p> Signup and view all the answers

What happens to the nucleus during the latter stages of apoptosis?

<p>It collapses and fragments into apoptotic bodies. (B)</p> Signup and view all the answers

What is the role of macrophages in the apoptosis process?

<p>They recognize, engulf, and digest apoptotic bodies. (D)</p> Signup and view all the answers

What role does the tumor suppressor protein p53 have in apoptosis?

<p>It activates BH3-only proteins to promote apoptosis. (B)</p> Signup and view all the answers

What is a consequence of high levels of anti-apoptotic proteins in cancer cells?

<p>Enhanced survival of damaged cells. (C)</p> Signup and view all the answers

Which of the following proteins are considered pro-apoptotic?

<p>BAX and BAK (B)</p> Signup and view all the answers

Which of the following actions is the function of the BH3-only proteins?

<p>To inhibit pro-survival proteins. (A)</p> Signup and view all the answers

What is MOMP and its significance in apoptosis?

<p>It leads to the release of apoptotic factors from mitochondria. (C)</p> Signup and view all the answers

What initial event triggers the apoptosis pathway?

<p>Receiving a death signal (D)</p> Signup and view all the answers

During which phase of apoptosis can the cell still be rescued?

<p>Reversible commitment to death (D)</p> Signup and view all the answers

What happens when the cell reaches the irreversible execution phase?

<p>Rescue becomes impossible (B)</p> Signup and view all the answers

What is the final stage of apoptosis characterized by?

<p>Degradation of cell components into vesicles (C)</p> Signup and view all the answers

How is adaptability represented in the apoptosis diagram?

<p>With a bar graph showing progressive decline (B)</p> Signup and view all the answers

What role do initiator caspases play in the apoptosis process?

<p>They activate executioner caspases through dimerization. (C)</p> Signup and view all the answers

What is the main characteristic of procaspases?

<p>They are inactive forms of caspases. (B)</p> Signup and view all the answers

How are executioner caspases activated in the apoptosis mechanism?

<p>They are cleaved and activated by dimerized initiator caspases. (A)</p> Signup and view all the answers

What happens to substrates when executioner caspases are activated?

<p>They are cleaved, leading to cellular components destruction. (C)</p> Signup and view all the answers

What is the role of dimerization in the activation of initiator caspases?

<p>It is essential for the activation of initiator caspases. (B)</p> Signup and view all the answers

What role does cytochrome C play in the intrinsic pathway of apoptosis?

<p>Activates APAF1 to form the apoptosome (A)</p> Signup and view all the answers

Which of the following initiates the intrinsic pathway of apoptosis?

<p>DNA damage, ER stress, hypoxia (D)</p> Signup and view all the answers

What is the outcome of the BAX and BAK heterodimer formation in apoptosis?

<p>Release of cytochrome C (C)</p> Signup and view all the answers

What does the apoptosome consist of?

<p>APAF1 with dimerized initiator caspase 9 (D)</p> Signup and view all the answers

Which of the following is NOT a step in the intrinsic pathway of apoptosis?

<p>Formation of death receptor complexes (A)</p> Signup and view all the answers

What is a key difference between necrosis and apoptosis regarding the number of cells affected?

<p>Only necrosis affects many cells (B)</p> Signup and view all the answers

How do macrophages interact with cells undergoing necrosis compared to apoptosis?

<p>Macrophages only ingest necrotic cell contents (D)</p> Signup and view all the answers

Which process is characterized by membrane blebbing while maintaining membrane integrity?

<p>Apoptosis (C)</p> Signup and view all the answers

In which mechanism of cell death is chromatin condensation and DNA degradation observed?

<p>Only in apoptosis (B)</p> Signup and view all the answers

What happens to organelles during necrosis compared to apoptosis?

<p>Organelles swell and leak in necrosis but not in apoptosis (A)</p> Signup and view all the answers

What role do Smac mimetics play in apoptosis pathways?

<p>They sequester anti-apoptotic IAPs. (B)</p> Signup and view all the answers

Which mechanism does c-FLIP inhibit to enhance apoptosis?

<p>It competes with pro-caspase-8. (B)</p> Signup and view all the answers

Which of the following proteins are antagonized by Bcl-2 family inhibitors?

<p>Bcl-2 and Bcl-xL (C)</p> Signup and view all the answers

What is the primary function of TRAIL in the apoptosis pathways?

<p>To induce apoptosis by binding to DR4 and DR5. (A)</p> Signup and view all the answers

What downstream effect does the activation of caspase-8 have in apoptosis?

<p>It activates pro-caspase-3. (C)</p> Signup and view all the answers

What role do adaptor proteins play in the extrinsic receptor pathway?

<p>They facilitate the dimerization of initiator caspases. (D)</p> Signup and view all the answers

Which factor is essential for the activation of the extrinsic pathway of apoptosis?

<p>Binding of a ligand to a death receptor. (C)</p> Signup and view all the answers

Which of the following initiator caspases are primarily involved in the extrinsic receptor pathway?

<p>Caspase 8 and 10 (C)</p> Signup and view all the answers

What is the purpose of the death-inducing signaling complex (DISC) in the extrinsic pathway?

<p>To recruit executioner caspases for apoptosis. (D)</p> Signup and view all the answers

Which of the following statements about the extrinsic receptor pathway is incorrect?

<p>It does not involve any adaptor proteins. (D)</p> Signup and view all the answers

Flashcards

Apoptosis

The process in which a cell undergoes self-destruction, following a specific series of steps.

Fragmentation

The process of the cell's internal contents being broken down into smaller parts.

Cell Shrinkage

The shrinking of the cell during apoptosis, leading to a smaller, denser form.

Blebbing

The formation of small, membrane-bound vesicles on the surface of a cell during apoptosis.

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Macrophages

Specialized immune cells that engulf and digest the fragmented remains of apoptotic cells.

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What makes neurons special in terms of division?

Neurons are unique because they cannot divide to replace themselves after damage or death.

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What are some causes of neuronal death?

Damage to neuronal connections, lack of crucial growth factors, and oxidative stress can all lead to neuronal death.

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What's the difference between synaptosis and apoptosis?

Loss of synapses (connection points between neurons) is a reversible process, while cell death via apoptosis is irreversible.

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What happens in neurodegenerative diseases?

Neurodegeneration is a process where neurons within specific brain regions die off due to diseases like Alzheimer's, Parkinson's, and Huntington's.

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Which brain regions are particularly vulnerable to neuronal death in neurodegenerative diseases?

The cerebral cortex, responsible for higher-level thinking, and the striatum, involved in movement control, are regions commonly affected by selective apoptosis in neurodegenerative diseases.

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TRAIL

A protein that triggers apoptosis by binding to death receptors (DR4 and DR5) on the cell surface.

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c-FLIP

A protein involved in the extrinsic apoptotic pathway, acting as a key regulator of caspase-8 activation.

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IAPs (Inhibitors of Apoptosis Proteins)

A group of proteins that prevent apoptosis by inhibiting caspases, crucial for cell survival.

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Bcl-2 Family Inhibitors

A class of drugs that block the anti-apoptotic function of Bcl-2 and Bcl-xL proteins, promoting apoptosis.

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What are caspases?

Caspases are a family of proteases that play a crucial role in apoptosis, or programmed cell death. They act as executioners, cleaving specific proteins to dismantle the cell.

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What are initiator caspases?

Initiator caspases are like the trigger for the apoptotic pathway, activating other caspases to carry out the cell destruction process.

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Smac Mimetics

Small molecules mimicking the function of Smac, promoting apoptosis by binding to and inhibiting IAPs.

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What are executioner caspases?

Executioner caspases are the main executors of apoptosis. They cleave numerous cellular components, leading to dismantling of the cell.

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What are procaspases?

Procaspases are the inactive form of caspases. They are like the executioner's tools kept locked and loaded, waiting for the activation signal.

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How are initiator caspases activated?

Initiator caspases activate by dimerization, forming a pair. This activation triggers the apoptotic cascade.

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What is p53?

A tumor suppressor protein that plays a central role in triggering apoptosis through the BCL-2 pathway. It helps prevent cancer by ensuring damaged cells are eliminated.

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How do pro-survival BCL-2 proteins impact apoptosis?

These pro-survival proteins, BCL-XL, MCL-1, and BCL-2, normally prevent apoptosis. However, when inhibited by BH3-only proteins, they allow apoptosis to proceed.

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What do BH3-only proteins do?

These proteins, BIM, PUMA, and NOXA, are activated by p53 and bind to pro-survival BCL-2 proteins, lifting the brakes on apoptosis.

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What happens during MOMP (Mitochondrial Outer Membrane Permeabilization)?

This process occurs when pro-apoptotic proteins, BAX and BAK, activate, disrupting the outer mitochondrial membrane and releasing factors that lead to caspase activation and cell death.

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What is the role of caspases in apoptosis?

These enzymes, caspases, act as executioners in apoptosis, dismantling the cell in a precise and organized manner.

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BCL-2 family proteins

A group of proteins that control apoptosis. They include pro-apoptotic proteins like BAX and BAK, and anti-apoptotic proteins like BCL-2.

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MOMP (Mitochondrial Outer Membrane Permeabilization)

A process where mitochondria release cytochrome c into the cytoplasm, initiating the intrinsic apoptotic pathway.

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Caspases

A family of enzymes that play a central role in apoptosis. They are 'executioner' proteins that dismantle the cell's machinery.

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Intrinsic Apoptosis Pathway

Apoptosis initiated by internal cell stress, such as DNA damage or lack of oxygen.

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Necrosis

A form of cell death that is triggered by external factors like injury, toxins, or lack of oxygen. It's like a cell exploding.

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Cell Number

In necrosis, multiple cells die simultaneously, while in apoptosis, only individual cells are affected.

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Membrane Integrity

Necrosis is characterized by the breakdown of the cell membrane, leaking its contents, while apoptosis involves the formation of blebs (small membrane-bound compartments) that prevent the release of harmful contents.

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Cell Debris Cleanup

In necrosis, the cell's debris is cleared by macrophages, while in apoptosis, neighboring cells directly engulf the apoptotic cell's fragments.

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What is the first step of apoptosis?

The death signal is received by the cell, triggering the apoptosis pathway. This is the first crucial step in the process.

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Can a cell reverse apoptosis?

The cell can still be rescued, as it is sensitive to survival factors, if they are present. During this stage, apoptosis is reversible.

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What happens when the cell enters irreversible commitment?

The cell has passed the point of no return and cannot be rescued. This is the irreversible 'execution' stage.

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What happens in the final stage of apoptosis?

The final stage of apoptosis, where the cell's components are broken down into smaller vesicles and removed by specialized cells. This completes the process.

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What is the purpose of apoptosis?

Apoptosis is a programmed cell death process that is important for regulating cell number and removing damaged cells. This process eliminates old or unhealthy cells, maintaining the health of an organism.

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TNFR superfamily

A group of receptors, including TNFR, Fas, and TRAIL receptors, that play a crucial role in initiating the extrinsic pathway of apoptosis.

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Adaptor proteins (FADD and TRADD)

Proteins that act as intermediaries, connecting the death receptors to initiator caspases.

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Death-inducing signaling complex (DISC)

A protein complex formed after the activation of death receptors, responsible for initiating the caspase cascade.

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Extrinsic apoptotic pathway

A signal transduction process triggered by external stimuli that ultimately leads to programmed cell death.

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What is apoptosis?

Apoptosis is a programmed process of cell death, where the cell actively self-destructs in a controlled manner, unlike the uncontrolled breakdown of necrosis.

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Why is apoptosis important?

Apoptosis is crucial for maintaining tissue homeostasis, removing damaged or unhealthy cells, and preventing cancer development by eliminating potentially harmful cells.

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What triggers apoptosis?

The "death signal" triggers a sequence of events that lead to the cell's self-destruction. This can come from internal signals (like DNA damage) or external signals (like a death receptor activation).

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Explain the seesaw analogy in apoptosis.

The "seesaw" represents the balance between pro-apoptotic proteins (promoting cell death) and anti-apoptotic proteins (preventing cell death). When the pro-apoptotic side overpowers the anti-apoptotic side, the cell commits to apoptosis.

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How does apoptosis play a role in development and health?

Apoptosis is essential for normal development and tissue remodeling. For example, during development, apoptosis removes excess cells, shaping organs and tissues. In adults, it helps to eliminate damaged cells, allowing for tissue repair and renewal.

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Study Notes

Apoptosis and Neurodegeneration

  • Neurons are post-mitotic (cannot replace themselves)
  • Neuronal death caused by loss of proper connections, loss of growth factors (e.g., NGF – nerve growth factor), ROS damage (especially oxidative damage)
  • Neuronal dysfunction or damage results in loss of synapses (synaptoisis; irreversible apoptosis)
  • Neuronal death underlies the symptoms of many human neurological disorders, including Alzheimer's, Parkinson's and Huntington's diseases.

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Description

Test your knowledge on apoptosis and its role in neuronal health. This quiz covers key concepts like physiological death signals, oxidative stress, and the effects of neurodegenerative diseases on brain function. Explore the intricate processes involved in cell death and the maintenance of homeostasis.

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