Sect 10 Quiz Easy

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Questions and Answers

What is the primary function of signal transduction in cells?

To inhibit cell communication.

To convert extracellular signals into cellular responses. (correct)

To isolate cells from external stimuli.

To convert cellular responses into extracellular signals.

Which class of receptors is characterized by their signaling mechanisms involving activation of G-Proteins?

G-Protein Coupled Receptors (correct)

Ubiquitin-Linked Receptors

Adjacent Cell Bind Receptors

Receptor Tyrosine Kinases

Which term describes the process of enhancing the strength of a cellular signal?

Signal termination

Signal transduction

Signal inhibition

Signal amplification (correct)

What role do second messengers play in signal transduction?

They serve as intermediaries that relay the signal within the cell. Signup and view all the answers

What is a common consequence of alterations in signal transduction pathways?

Development of human diseases. Signup and view all the answers

Which component is typically involved in the activation of receptor tyrosine kinases?

Phosphorylation of tyrosine residues Signup and view all the answers

Which concept is NOT generally associated with G-Protein coupled receptors?

Direct regulation of gene expression Signup and view all the answers

What is the role of adapter proteins in signal transduction?

Link different signaling molecules together. Signup and view all the answers

What is the primary function of a ligand when binding to a receptor protein?

To alter the receptor's properties Signup and view all the answers

How is ligand specificity determined?

Through noncovalent interactions with amino acids Signup and view all the answers

What does the dissociation constant (Kd) indicate?

The affinity of the receptor for the ligand Signup and view all the answers

Which is a feature of second messengers in intracellular signaling?

They amplify external signals within a cell Signup and view all the answers

What is the role of GTPase switch proteins in cell signaling?

To act as molecular switches within signaling pathways Signup and view all the answers

Which of the following describes the general response of a cell to a particular ligand?

It generally occurs with low ligand concentrations Signup and view all the answers

What is a characteristic of effectors in signaling pathways involving second messengers?

They can be either enzymatic or nonenzymatic proteins Signup and view all the answers

What happens to the ligand and receptor in target cells after they interact?

They may be modified or degraded Signup and view all the answers

What is the primary role of trimeric G proteins in GPCR signaling pathways?

To transduce signals from receptors to effector proteins Signup and view all the answers

Which subunit of the trimeric G protein is primarily involved in switching between active and inactive forms?

Ga Signup and view all the answers

Which structure of the GPCR is essential for binding ligands?

Seven membrane-spanning domains Signup and view all the answers

Which effector protein is commonly activated by GPCRs to enhance cAMP synthesis?

Adenylyl Cyclase Signup and view all the answers

What action do hormone-occupied receptors perform in relation to Ga proteins?

Act as GEFs for Ga proteins Signup and view all the answers

What is the function of cAMP phosphodiesterase in GPCR signaling?

To hydrolyze cAMP to AMP Signup and view all the answers

Which of the following statements about GPCRs is true?

GPCRs can stimulate or inhibit adenylyl cyclase Signup and view all the answers

What is a characteristic of feedback regulation in GPCR signaling pathways?

It can lead to desensitization of the pathway Signup and view all the answers

What is the primary result of the intrinsic GTPase activity of Gas?

Inactivation of the Gas protein Signup and view all the answers

What role does cAMP phosphodiesterase play in cellular response?

Hydrolyzes cAMP to 5’-AMP Signup and view all the answers

What is required for continued activation of adenylate cyclase?

Presence of hormones Signup and view all the answers

What effect do anchoring proteins have on cAMP?

They restrict cAMP effects to specific locations Signup and view all the answers

Which protein phosphorylates GPCR receptors leading to receptor endocytosis?

BARK Signup and view all the answers

What does phosphorylated CREB do in signal transduction?

Stimulates transcription of target genes Signup and view all the answers

What is the role of b-arrestin in the receptor desensitization process?

Facilitates GPCR endocytosis Signup and view all the answers

What kinases can be activated by the GPCR-arrestin complex?

c-Src and MAP kinases Signup and view all the answers

What happens to the Notch extracellular domain once it is released?

It is endocytosed by the signaling cell Signup and view all the answers

Which subunit of the g-secretase complex binds to the Notch stump generated by ADAM 10?

Nicastrin Signup and view all the answers

What is the role of Notch's cytoplasmic segment after being released?

It modulates gene transcription Signup and view all the answers

How do the Wnt and Hedgehog signaling pathways primarily get activated?

Through the binding of secreted proteins to receptors Signup and view all the answers

Which of the following accurately describes the role of GSK3 in signaling pathways?

It phosphorylates and inactivates key components Signup and view all the answers

What happens to transcription factors in the resting state within the Wnt and Hedgehog pathways?

They are ubiquitinated and inactivated Signup and view all the answers

What receptor does Wnt primarily signal through?

Frizzled (Fz) Signup and view all the answers

What consequence can activating mutations in Wnt and Hedgehog pathways have?

They can result in cancer Signup and view all the answers

What is the role of ubiquitin ligase (E3 TrCP) in relation to b-catenin?

It promotes the degradation of b-catenin Signup and view all the answers

What event occurs when Wnt binds to Frizzled (Fz) and LRP?

Phosphorylation of LRP by GSK3 Signup and view all the answers

How does Hedgehog (Hh) influence Cubitis interruptus (Ci) transcription factor?

By generating an activating form of Ci Signup and view all the answers

What post-translational modifications occur on the N-terminal fragment of Hedgehog?

Modification with cholesterol and palmitoyl Signup and view all the answers

What happens to Patched and Smoothened upon Hedgehog binding to Patched?

They alter their subcellular location Signup and view all the answers

In the absence of Hedgehog, what is the role of Patched (Ptc)?

Inhibits the signaling pathway Signup and view all the answers

What is the role of the complex involving Fused (Fu), Costal-2 (Cos2), and Ci?

It binds to microtubules Signup and view all the answers

What common feature distinguishes Hedgehog signaling from Wnt signaling?

Post-translational modification of the signaling molecule Signup and view all the answers

Study Notes

Cell Signaling - Signal Transduction

Signal transduction converts extracellular signals into cellular responses
Extracellular signaling regulates interactions between unicellular and multicellular organisms
Cells communicate, and no cell lives in isolation
Signal transduction pathways are conserved
Signal transduction involves steps from extracellular signals to cellular responses
Signal transduction can be hydrophilic or hydrophobic
Hydrophilic signaling molecules cannot diffuse across the membrane, binding to cell-surface receptors.
Example hydrophilic molecules include peptides, etc.
Example hydrophobic molecules include steroids, etc.
Signal transduction includes intracellular signal transduction pathways
Different signaling molecules can activate intracellular signaling pathways or use intracellular signaling components differently
Receptors and signaling molecules bind in specific ways
Maximal response of a cell depends on the ligand concentration
Receptors activate a limited number of signaling pathways
Cells modify or degrade signals to terminate a response
Signaling molecules operate at various distances
Signaling by membrane attached signals or juxtaposed cells is called juxtaposed signaling
Intracellular signal transduction includes second messengers, conserved proteins (GTPase switch proteins, kinases, phosphatases), resetting or termination of the signal, and regulation/interaction of signaling pathways
Second messengers are intracellular signaling molecules that carry signals from receptors.
Examples of second messengers include cAMP, cGMP, DAG, IP3.
The concentration of second messengers is modulated by binding of ligands to cell surface receptors
Second messengers regulate activities of enzymes and nonenzymatic proteins
GTPase switch proteins are conserved GTP-binding proteins that act as on-off molecular switches
Protein kinases phosphorylate Ser or Thr residues to activate or inactivate the protein
Protein phosphatases remove phosphate residues to activate or inactivate the targets
Adapter proteins coordinate the formation of multicomponent signaling complexes
Multiple signaling pathways can integrate responses in different tissues
Receptors are on cell surfaces or intracellularly based on ligand type
Ligand specificity is determined by the noncovalent protein interactions
Ligand binding often changes the receptors' properties
Receptors can activate a limited number of signaling pathways in target cells
Receptor desensitization occurs at high ligand concentrations

G Protein-Coupled Signal Transduction Pathway

Trimeric G proteins transduce signals from cell-surface receptor to effector proteins
G proteins have a receptor that contains seven transmembrane domains
G proteins can be further divided into classes based on how they bind ligands

Receptor Tyrosine Kinase Pathways

Receptor tyrosine kinases (RTKs), recognize soluble or membrane-bound peptide/protein hormones as growth factors
Binding of a ligand to RTKs stimulates tyrosine kinase activity, initiating cascades that result in gene expression in target cells
RTK pathways are important for cell proliferation, differentiation, survival, and cellular metabolism

Notch/Delta Signaling Pathway

Extracellular signaling molecules are on juxtaposed cells
Notch receptors on a cell bind to a Delta protein on a neighboring cell
This results in two proteolytic cleavages in the Notch receptor
Released Notch cytoplasmic segment acts as transcription factor in the nucleus to modulate transcription

Signaling Controlled by Ubiquitination

Ubiquitination and proteolysis of proteins are important in signal transduction pathways, such as Wnt and Hedgehog.
Target proteins can be transcription factors or transcription factor inhibitors.
Various proteins and signaling pathways can contribute to development and diseases.
Signal transduction pathways are involved in important events, such as neural tube closure, limb development, heart development, and other critical developmental events.

NF-κB Pathway

NF-κB is a transcription factor crucial for cellular response to infection and inflammation.
The degradation of IκBα protein activates NF-κB to initiate transcription of target genes in the nucleus
NF-κB pathway involves several steps, including ligand binding, receptor activation, IκB kinase (IKK) phosphorylation/activation, ubiquitination and degradation of IκBa, translocation of NF-κB to the nucleus, and finally transcription of target genes within the nucleus

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Description

Explore the fascinating world of signal transduction, where extracellular signals are converted into cellular responses. This quiz covers key concepts such as hydrophilic and hydrophobic signaling molecules, receptor interactions, and the pathways involved in cellular communication. Test your knowledge of how cells communicate and respond to their environment.