Cellular Homeostasis and Energy Production
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Questions and Answers

What is the primary role of the ubiquitin system?

  • Synthesizing new proteins
  • Promoting cell division
  • Maintaining protein homeostasis (correct)
  • Modulating water balance

    • The ubiquitin system only plays a role in protein degradation and does not affect cell signaling or DNA repair.

    False (B)

    Which protein complex is responsible for degrading ubiquitinated proteins?

    26S proteasome

    The enzyme that activates ubiquitin in an ATP-dependent manner is called _________.

    <p>E1</p> Signup and view all the answers

    Match the ubiquitin system enzyme with its function:

    <p>E1 = Activates ubiquitin in an ATP-dependent manner E2 = Transfers activated ubiquitin E3 = Facilitates the transfer of ubiquitin to the target protein</p> Signup and view all the answers

    What happens to the ubiquitin molecules after a protein is degraded by the 26S proteasome?

    <p>They are recycled for future use (B)</p> Signup and view all the answers

    E3 ligases have low substrate specificity and can ubiquitinate a wide range of proteins.

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

    How does the ubiquitin system help in regulating the cell cycle?

    <p>By degrading key cell cycle regulators, such as cyclins, at specific stages</p> Signup and view all the answers

    Which of the following cells are responsible for destroying infected cells and tumors?

    <p>Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells (A)</p> Signup and view all the answers

    Granzyme B is a serine protease that cleaves after aspartic acid residues.

    <p>True (A)</p> Signup and view all the answers

    What are the two main pathways by which Granzyme B induces apoptosis?

    <p>Caspase-dependent and caspase-independent mechanisms</p> Signup and view all the answers

    Granzyme B can directly activate ______ and trigger apoptosis at multiple points of the caspase-dependent pathway.

    <p>caspase 3</p> Signup and view all the answers

    Match the following proteins with their roles in apoptosis:

    <p>Granzyme A = Cleaves linker histone H1, opening chromatin and enhancing DNA fragmentation Granzyme B = Cleaves and activates caspase 8, as well as caspases 3, 6, and 7 Perforin = Forms pores in the target cell membrane BID = Upon cleavage by Granzyme B, promotes release of cytochrome C from mitochondria Caspase 3 = One of the key executioner caspases in the apoptotic pathway EndoG = A mitochondrial protein that can induce oligonucleosomal DNA damage when released</p> Signup and view all the answers

    Targeting the sumoylation mechanism is considered a promising therapeutic strategy for which disease?

    <p>Breast cancer (D)</p> Signup and view all the answers

    Oxidative phosphorylation, autophagy, protein ubiquitination, and sumoylation are all cellular processes that work independently of each other.

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

    Which of the following proteins are naturally occurring inhibitors of caspases?

    <p>All of the above (D)</p> Signup and view all the answers

    How does Granzyme B contribute to the disruption of the mitochondrial transmembrane potential?

    <p>The mechanism is unknown</p> Signup and view all the answers

    What is another term for programmed cell death?

    <p>apoptosis</p> Signup and view all the answers

    Apoptosis results in controlled cell shrinkage and nuclear fragmentation via the action of proteolytic enzymes called ______.

    <p>caspases</p> Signup and view all the answers

    Match the following cell death mechanisms with their primary characteristics:

    <p>Apoptosis = Controlled cell shrinkage and nuclear fragmentation Necrosis = Cell swelling, lysis and pro-inflammatory cytokine release Autophagy = Destroys the cell’s damaged proteins and organelles via a catabolic process</p> Signup and view all the answers

    Which of the following is NOT a result of apoptosis?

    <p>Pro-inflammatory cytokine release (A)</p> Signup and view all the answers

    Necrosis is a highly regulated cellular process.

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

    Which receptor is involved in signaling leading to necrosis?

    <p>RIPK1</p> Signup and view all the answers

    Autophagy destroys the cell's damaged proteins and organelles via an intracellular catabolic process in the ______

    <p>lysosome</p> Signup and view all the answers

    Which of the following physiological process relies on autophagy?

    <p>growth regulation (B)</p> Signup and view all the answers

    Which of the following pathways is NOT involved in apoptosis?

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

    The intrinsic apoptosis pathway is activated by external signals from other cells.

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

    What are the key regulators shared by autophagy and apoptosis?

    <p>BCL2 family members</p> Signup and view all the answers

    ___ T Lymphocytes are responsible for inducing apoptosis in infected or cancerous cells.

    <p>Cytotoxic</p> Signup and view all the answers

    Match the following apoptosis pathways with their triggers:

    <p>Intrinsic Pathway = DNA damage or radiation Extrinsic Pathway = Signals from TNF family death receptors Caspase 9 = Activated by intrinsic pathway Caspase 8 = Activated by extrinsic pathway</p> Signup and view all the answers

    Which caspases are activated by the extrinsic apoptosis pathway?

    <p>Caspase 3, 6, 7 (A)</p> Signup and view all the answers

    Overactive apoptosis may lead to neurodegenerative diseases.

    <p>True (A)</p> Signup and view all the answers

    What condition may result from abnormalities preventing apoptosis?

    <p>Cancer</p> Signup and view all the answers

    Cytotoxic T Lymphocytes target cells displaying ___ epitopes.

    <p>foreign</p> Signup and view all the answers

    Which of the following describes the role of caspase 9 in apoptosis?

    <p>Triggered by intrinsic apoptosis pathway (C)</p> Signup and view all the answers

    What is the mechanism by which granzyme A induces cell death?

    <p>Caspase-independent (C)</p> Signup and view all the answers

    Granzyme B is more abundant than granzyme A.

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

    What unique form of DNA damage does granzyme A cause?

    <p>Single-stranded DNA nicking</p> Signup and view all the answers

    Granzyme A targets the SET complex that contains two tumor suppressor proteins: pp32 and _______.

    <p>GAAD/NM23H1</p> Signup and view all the answers

    Match the following components with their associated functions:

    <p>Granzyme A = Caspase-independent cell death SET complex = DNA repair and transcriptional activation Perforin = Delivery of granzymes into target cells NK cells = Targeted destruction of infected and tumor cells</p> Signup and view all the answers

    Which process is primarily used by CTL and NK cells to destroy target cells?

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

    Granzyme A spares the nucleosome assembly protein SET during its actions.

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

    What feature of apoptosis does granzyme A cause that is characteristic during cell death?

    <p>Membrane blebbing</p> Signup and view all the answers

    Granzyme A is delivered to target cells through _______.

    <p>Perforin</p> Signup and view all the answers

    Which of the following is NOT a characteristic feature caused by granzyme A?

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

    Study Notes

    Cellular Homeostasis

    • Cellular homeostasis is maintaining stable conditions within cells
    • It's crucial for cell survival and optimal functioning
    • Maintaining stable internal conditions allows biochemical processes to occur effectively
    • Disruptions can lead to cellular stress, dysfunction, or death, contributing to diseases
    • Maintaining this balance is vital for organism health

    Energy Production

    • Oxidative phosphorylation (OXPHOS) is the primary energy production pathway in mitochondria
    • OXPHOS generates adenosine triphosphate (ATP), the main energy source
    • The process begins with breakdown of nutrients like glucose
    • The citric acid cycle is involved in this process, in which high energy molecules donate electrons
    • Proton gradient across the inner mitochondrial membrane is created, driving ATP synthesis

    Cellular Cleanup, Recycling, and Quality Control

    • Mechanisms for segregating and degrading malfunctioning or obsolete cell components are essential to maintain cell health
    • These processes prevent build-up of damaged proteins and organelles, which can be toxic leading to disease.
    • Recycling of components allows cells to reuse valuable molecules

    Autophagy

    • Autophagy is a cellular process involved in degradation and recycling of cellular components
    • It acts as a cellular housekeeping system, removing damaged or obsolete components
    • This process provides nutrients and energy during periods of stress or starvation
    • Autophagy is crucial for cellular health and maintenance.

    Protein Ubiquitination

    • Protein ubiquitination is a post-translational modification where proteins are tagged with ubiquitin
    • It's vital for protein function regulation, localization, and stability
    • Ubiquitination often signals for protein degradation
    • The ubiquitination system helps maintain protein homeostasis by removing damaged or misfolded proteins

    Fine-Tuning of Cellular Processes

    • Sumoylation is a subtle modification process for cellular adjustments
    • Sumoylation involves attaching SUMO-proteins to specific amino acids
    • Modifying stability, function, or localization of a protein through sumoylation provides a finely tuned cellular response
    • Sumoylation is essential for maintaining cellular homeostasis

    Apoptosis

    • Apoptosis (programmed cell death) is a highly regulated biological process involved in controlled cell removal
    • Apoptosis can be triggered by extracellular or intracellular signals
    • Controlled cell shrinkage, membrane blebbing and nuclear fragmentation are characteristic of apoptosis
    • This tightly regulated process is crucial to prevent cell damage and uncontrolled cell proliferation.

    Death Receptor Signaling

    • Several factors and ligands can initiate apoptosis (programmed cell death)
    • Death receptors, part of the tumor necrosis factor receptor superfamily, are triggered by death ligands and cause apoptotic or survival signals
    • Disruptions can lead to uncontrolled cell proliferation or survival.

    Granzyme A Signaling

    • Cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells use granzyme A and granzyme B for targeted killing and apoptosis induction
    • These enzymes trigger caspase-independent mechanisms contributing to apoptosis
    • The tryptase granzyme A causes characteristic apoptosis features

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    Cellular Homeostasis: A Comprehensive Overview PDF

    Description

    This quiz explores key concepts of cellular homeostasis, energy production through oxidative phosphorylation, and the importance of cellular cleanup and recycling mechanisms. Understanding these processes is essential for grasping how cells maintain their functionality and contribute to overall organism health. Test your knowledge on these fundamental biological principles!

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