Cell signalling - Week 22 & 23 Flashcards
what is signaling and signal transduction meaning
Signaling and signal transduction are interchangeable terms that refer to the complex process by which cells communicate and respond to stimuli. It involves molecular events triggered by binding of signaling molecules to receptors, leading to cellular responses.
what is signal transduction
Signal transduction is the process by which an extracellular signal, such as a hormone, neurotransmitter, or growth factor, is converted into an intracellular signal inside a cell. This conversion typically involves a cascade of molecular events, including receptor activation, intracellular signaling molecule activation, and ultimately leading to a cellular response.
what is the pathway of cellular signal transduction sequence occur in
STIMULI –>SENSOR–> SIGNAL TRANSDUCTION–> RESPONSE(receptor)
- Cells sense environmental signals via receptors.
- Receptors trigger intracellular signal transduction pathways.
- Signal transduction leads to cellular responses.
This simplified sequence captures the key steps of how cells detect, transmit, and respond to signals, allowing them to adapt and function in response to their environment.
how are signal in cellular signal transduction regulated and why
signals in cellular signal transduction are regulated in both time and space. Cells carefully regulate the timing and location of signal transduction events to ensure precise and coordinated cellular responses.
what does normal cell signaling play a role in
Normal cell signaling plays a critical role in regulating many, if not all, aspects of whole body homeostasis. Cell signaling pathways are involved in coordinating and regulating various physiological processes in the body, including metabolism, growth and development, immune responses, neuronal signaling, hormone regulation, and many others.
what is a effector
a component of a signalling pathway that is activated following engagement of a receptor.
what is signal transduction pathway meaning
the set of molecular events that convert one specific signal into one specific cellular response.
what is a ligand
A molecule coming from a distance that binds to a receptor on the surface or inside a cell, acting as the primary messenger.
what is a receptor
Proteins on the cell surface or inside the cell that bind to specific ligands and transmit the signal to the cell’s interior.
what are second messengers
Intracellular signaling molecules that are produced in response to ligand-receptor binding and transmit the signal further within the cell.
what are target genes
Specific genes in the cell’s DNA that are regulated by the intracellular signals and can be influenced by the second messengers.
what are some example of ligands
Ligands can include a wide range of molecules that can bind to receptors and initiate cellular signal transduction. Some examples of ligands include:
* Growth factors and cytokines
* Hormones
* Cell Adhesion Molecules
* Lipids
* Neurotransmitters
what are some examples of different types of receptors
some examples of different types of receptors are:
* Receptor tyrosine kinases
* G-protein-coupled receptors
* Nuclear receptors
what are some examples of different types of transducers
some examples of different types of transducers are:
* Small monomeric GTPases
* Kinases
how is mating in yeast cells carried out in 3 steps
Yeast sexual mating is regulated by signal transduction,
which involves a series of events that ultimately lead to:
1. the exchange of mating factors
2. mating,
3. the formation of a new a/α cell.
how do cells communicate to each other
Cells have the ability to sense and respond to specific chemical signals in their environment, allowing them to communicate with each other. This communication can occur directly through cell-cell contacts or indirectly through the release of chemical signals into the extracellular environment.
why is cells being able to communicate with each other crucial
In multicellular organisms, this ability to communicate and respond to signals is crucial for achieving coordinated activities among different specialized cells and tissues. It allows for the development, growth, and maintenance of the organism, as well as the regulation of homeostasis.
what are 2 examples of cell signalling
There are different types of cell signaling, including:
1. Endocrine signaling: This type of signaling involves the release of chemical signals, called hormones, into the bloodstream by endocrine glands.
2. Paracrine signaling: This type of signaling involves the release of chemical signals, called local mediators, by cells that act on nearby cells within the same tissue or organ.
what does cell signalling involve and why
cell signaling involves the reception, transduction, amplification, integration, and response to signals, which allows cells to communicate and respond to their environment
what can messenger molecules be chemically charaterised by
Messenger molecules, also known as signaling molecules or ligands, can be chemically characterized as amino acids (or derivatives), peptides, proteins, fatty acids, nucleosides, or nucleotides
where do hydrophilic and hydrophobic messenger molecules usually work/act
messenger molecules can be hydrophilic, meaning they dissolve in water, and typically act on receptors on the cell surface. Hydrophobic messengers, on the other hand, are typically not soluble in water and tend to act on receptors located in the nucleus or cytosol of the target cell.
what is the interaction between the messenger molecule and its receptor known as
The interaction between the messenger molecule and its specific receptor is often likened to a “key and lock” mechanism, where the ligand (key) fits into the receptor (lock) to initiate a cellular response.
what can steroid hormones and retinoids regulate
hydrophobic messengers, such as steroid hormones and retinoids can regulate gene transcription, leading to changes in gene expression and subsequent cellular responses.
how do cell distinguish messengers from other chemicals in the environment
The combination of receptor specificity, ligand-receptor interactions, and the positioning of appropriate amino acid side chains in the binding site of the receptor allow cells to distinguish messengers from other chemicals in the environment and ensure high specificity in ligand-receptor interactions, allowing for precise signaling and communication within cells.
how do ligands bind to their receptors with high specificity
Ligands form multiple noncovalent bonds with
their binding site in the receptor
how does ligand bind to its receptor
The binding of a ligand to its receptor is similar to the binding of an enzyme to its substrate. When a receptor binds its ligand, it becomes occupied.
what is the amount of receptos that is occupied proportional to
The amount of receptor that is occupied by the ligand is proportional to the concentration of free ligand in solution. As the ligand concentration increases, more receptors become occupied until most of them are occupied, reaching saturation.
what are growth factors and cytokines, where are they involved, with example
Peptides/small proteins secreted from cells,
involved in paracrine and autocrine signalling. e.g. Epidermal Growth Factor (EGF)
what are hormones, where are they involved, with example
Peptides, amino acids or small molecules (e.g. steroids) involved in endocrine signalling. e.g. Testosterone
what are cell adhesion molecules involved in, with examples
Cell Adhesion Molecules are Involved in direct interaction between cells e.g. Cadherins, or interaction between cells and the extracellular matrix e.g. Integrins
what are lipids, where are they involved, with example
Hydrophobic signalling molecules involved in autocrine and paracrine signalling e.g. prostaglandin
what are neutransmitters, what do they, with example
Small hydrophilic molecules, often derived from amino acidsor nucleotides.
Transmit signals across a synapse e.g. dopamine
How do GPCRs and Kinase Coupled Receptors transmit signals upon ligand binding, and what are the downstream signaling pathways they activate
Plasma membrane receptors are diverse and can be classified as G-Protein Coupled Receptors (GPCRs) or Kinase Coupled Receptors. Upon ligand binding, GPCRs activate intracellular G-proteins, while Kinase Coupled Receptors activate kinase activity.
why do downstream signaling pathways of GPCRs and Kinase Coupled Receptors diverge/converge
Downstream signaling pathways can diverge or converge which allows cells to integrate and process multiple signals for precise cellular responses. These signaling events play critical roles in cell function and development.
How do RTKs transmit signals upon ligand binding and the role of tyrosine phosphorylation in this process
Enzyme-linked receptors, like Receptor Tyrosine Kinases (RTKs), undergo conformational changes and dimerization upon ligand binding, activating their intrinsic kinase activity. This results in phosphorylation of tyrosine residues, which serve as binding sites for other proteins.
