Cell Signaling Types and Stages

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Questions and Answers

What is the primary function of endocrine ligands?

Facilitating contact-dependent signaling

Targeting cells near the original cell

Targeting a distant cell through the bloodstream (correct)

Targeting itself

What is the role of relay molecules in a signal transduction pathway?

They facilitate the reception of the signal

They participate in the transduction of the signal (correct)

They initiate the cell response

They activate cellular responses

What is the initial transduction of the signal often triggered by?

The activation of relay molecules

A conformational change in the receptor (correct)

The response of the cell

The binding of the signal molecule to the receptor

What is a characteristic of the binding between a signal molecule and a receptor?

It is highly specific Signup and view all the answers

Where are most signal receptors located?

On the plasma membrane Signup and view all the answers

What is the final stage of cell signaling?

Response Signup and view all the answers

Which type of ligand targets cells near the original cell?

Paracrine ligand Signup and view all the answers

What type of signaling requires cells to be in direct membrane-membrane contact?

Contact-dependent signaling Signup and view all the answers

What is the primary function of second messengers in signal transduction?

To carry out various cellular functions such as sight, inflammation, and growth Signup and view all the answers

What type of ligands can diffuse across the plasma membrane of target cells?

Hydrophobic ligands Signup and view all the answers

What is the result of a ligand binding to a tyrosine kinase receptor?

Dimerization of the kinase domains Signup and view all the answers

What is the function of G-protein coupled receptors (GPCRs)?

To activate an entire cascade of proteins (enzymes) Signup and view all the answers

What is the role of ion channels in signal transduction?

To allow hydrophilic ions to pass through the plasma membrane Signup and view all the answers

What is the result of a ligand binding to a G-protein coupled receptor?

Activation of an entire cascade of proteins (enzymes) Signup and view all the answers

What type of receptors are involved in the binding of hydrophilic ligands?

Cell-surface receptors Signup and view all the answers

What is the final outcome of signal transduction pathways?

A change in cellular behavior or response Signup and view all the answers

What is the primary function of phosphatase enzymes in signal transduction pathways?

To remove phosphates from proteins Signup and view all the answers

What is the role of adenylyl cyclase in signal transduction?

To convert ATP to cAMP Signup and view all the answers

What is the function of G-proteins in signal transduction pathways?

To activate adenylyl cyclase Signup and view all the answers

What is the primary function of kinases in signal transduction pathways?

To add phosphates to proteins Signup and view all the answers

What is the term for the extracellular signal molecule that binds to the receptor in a signal transduction pathway?

First messenger Signup and view all the answers

What is the primary function of second messengers in signal transduction pathways?

To participate in pathways initiated by G-protein-linked receptors and receptor tyrosine kinases Signup and view all the answers

What is the term for the process by which a signal is transmitted through a series of protein activations?

Cascade of protein activations Signup and view all the answers

What is the primary function of receptors in signal transduction pathways?

To bind to extracellular signal molecules Signup and view all the answers

Study Notes

Types of Cell Signaling Molecules

Endocrine ligands target distant cells through the bloodstream, e.g., hormones
Paracrine ligands target cells near the original cell, e.g., neurotransmitters
Autocrine ligands target themselves
Contact-dependent ligands require direct membrane-to-membrane contact

Stages of Cell Signaling

Reception: binding of signal molecule (ligand) to a receptor
Transduction: conversion of the signal into a form that can bring about a response
Response: change in behavior that occurs in the cell as a result of the signal

Reception

Binding of a signal molecule (ligand) to a receptor is highly specific
Conformational change in the receptor often initiates signal transduction
Most signal receptors are plasma membrane proteins

Transduction

Signal initiated by conformational change of receptors
Process of activating a series of proteins inside the cell from the cell membrane, e.g., relay proteins and/or second messengers

Response

Change in behavior that occurs in the cell as a result of the signal

Receptors

Classified according to the type of ligands they bind
Hydrophobic ligands (e.g., steroids, vitamin D3) bind to intracellular receptors
Hydrophilic ligands bind to cell-surface receptors

Types of Cell-Surface Receptors

G-Protein Coupled Receptors (GPCRs)

Receive a large number of signals from diverse groups
Mechanism of action: ligand binds to receptor, activating G-protein, which activates enzymes and second messengers that carry out various functions

Tyrosine Kinase

Ligand binds to the receptor, leading to dimerization of the kinase domains
Phosphorylation of intracellular proteins allows them to bind and activate

Ion Channel

Allow hydrophilic ions to pass through the plasma membrane
Ligand binding opens the channel, e.g., neurotransmitters acting as ligands for Na+ ions

Signal Transduction Pathways

Molecules relay a signal from receptor to response, usually proteins
Signal transduction cascade: each protein activates the next, until the response is activated
Protein Phosphorylation and Dephosphorylation: a cascade of protein phosphorylations (kinases) and dephosphorylations (phosphatases) acts as a molecular switch

Second Messengers

Small, nonprotein, water-soluble molecules or ions
Participate in pathways initiated by G-protein-linked receptors and receptor tyrosine kinases
Examples: cyclic AMP (cAMP), ions, etc.

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Description

This quiz covers the different types of cell signaling molecules, including endocrine, paracrine, and autocrine ligands, as well as the stages of cell signaling, such as reception, transduction, and response.