Basic cell Signaling 1-16 Flashcards
Example of a fight or flight response:
Pancreatic cells release insulin to tell muscle cells to take up sugar from the blood for energy
What is cell signaling?
cell signalling is part of a complex system of communication to control and maintain normal physiological balance within the body and coordinates cell actions
What is the importance of cell signalling?
control and maintain normal physiological balance within the body and coordinates cell actions
Activation of different signalling pathways leads to diverse physiological responses such as….
- Cell proliferation
- Cell death
- Cell differentiation
- Tissue repair
- Immunity
- Metabolism
Explain the process of Cell Signalling:
- Signal (stimulus)
- Receptor
- Transduction
- Response
- Cell proteins called receptors detect the stimulus or signal
- Once a receptor protein receives a signal, it undergoes a conformational change, which in turn launches a series of biochemical reactions within the cell
- These intracellular signalling pathways, called signal transduction cascades, typically amplify the message
- The final effect is to trigger a cell’s response, such as the activation of gene expression
What is the purpose of the intracellular signalling?
Amplify the message
List the 4 types of cell signalling:
- Endocrine signalling
- Autocrine signalling
- Paracrine signalling
- Direct cell-cell contact
Explain the characteristics of endocrine signalling:
Long-distance endocrine signalling,
signals (hormones) produced by endocrine glands are released in the bloodstream which carries them to target cells in distant parts of the body
Types of hormones:
-Peptide hormones, steroid hormones
Explain the characteristics of Paracrine signalling:
(Neighboring signalling)
Signal molecule only affects target cells in the proximity of the signalling cell
A unique example is the conduction of an electric signal from one nerve cell to another nerve cell or to a muscle cell. (Synapse communication) In this case the signalling molecule is a neurotransmitter
Explain the characteristics of Autocrine signalling:
(Self signalling)
A cell signals itself, releasing a ligand that binds to receptors on its own surface
Explain the characteristics of Direct cell-cell signalling:
Tiny channels that directly connect neighbouring cells.
These water filled channels allow small signalling molecules, called intracellular mediators to diffuse between the 2 cells
Small molecules such as electrolytes (Ca2+, K+, Na+), are able to move between cells, but large molecules like proteins cannot fit through the channels without special assistance
Give an example of an intracellular mediator:
What can pass through and what cannot?
Small molecules such as electrolytes (Ca2+, K+, Na+), are able to move between cells, but large molecules like proteins cannot fit through the channels without special assistance
Define receptor and ligand:
Receptor-protein molecule that receives chemical signals from outside a cell
Ligand: Signal molecule that binds to a receptor
What happens when a ligand binds to a receptor?
Results in a conformational change
Binding of a ligand to a receptor changes the shape or activity of a receptor, allowing it to transmit a signal or directly produce a change inside of the cell
What are the 2 types of receptors?
- Intracellular receptor- found inside of the cell (in the cytoplasm or nucleus)
- Cell surface receptors, which are found in the cell membrane
Describe the characteristics of ligands of intracellular receptors:
Give an example of one
Small and hydrophobic molecules
Primary receptors for hydrophobic steroid hormones, such as the sex hormones estradiol (an estrogen)
Name the 3 main kinds of cell surface receptors:
- Channel linked receptors
- Enzyme linked receptors
- G protein-coupled receptors
What is the function of membrane anchored proteins?
Bind to ligands outside the cell
Ligand does not need to cross the cell membrane. So, the chemical structure of ligands are more diverse
What is Signal transduction?
Describes the process of converting external signals (e.g hormones, growth factors, neurotransmitters) to a specific internal cellular response (gene expression, cell division, cell death)
The receptors trigger a biochemical chain of events (signalling cascade) inside the cell eventually lead to a response
Common goal of signalling pathways
To produce a cellular response
Give examples of a cell response:
- Control of gene expression
2. Changes in cell metabolism
Cellular response types
At the molecular level
At the macroscopic level
Molecular level-changes such as an increase in specific gene (transcription), changes in activity of particular enzymes
Macroscopic level- changes in outward behaviour or appearance of the cell, such as cell growth or cell death, that are caused by the molecular changes
What is gene expression?
process in which information from a gene is used to produce a functional product, typically a protein
Only a fraction of the genes in a cell are expressed at any one time
To live, cells must be able to respond to changes in their environment. Regulation of the two main steps…
Transcription and translation is critical to this adaptability