Cell communication Flashcards
What are the two different types of local signalling and give examples.
- Paracrine signalling which occurs on nearby cells (fibroblast growth factor)
- Synaptic signalling which occurs in the nervous system (Neurotransmitter called acetylcholine).
Give an example of an endocrine cell signalling
Endocrine cell signalling is a type of long distance cell signalling, where insulin (hormone) travels to other organs to regulate blood glucose.
What are the different types of membrane bound receptors and what does it mean to be membrane bound?
GPCR, Receptor Tyrosine Kinase, ligand-gated ion channel and it means these receptors are on the outer surface of the cell’s membrane. This is so they receive signals from outside the cell (water-soluble molecules) as these molecules can’t go inside.
How many times can a GPCR weave in and out of the cell membrane?
7 times
At what stage in cell signalling does the enzyme activate?
The enzyme becomes activated once the G protein binds to it.
What lets the G protein to bind to the GPCR?
The change of shape of the GPCR (Conformational change).
Explain the steps of ligand gated ion channels.
- A ligand will bind to the ligand gated ion channel receptor on a specific site
- As the binding occur, it will change the shape of the ligand gated ion channel which will trigger the opening and closing of the gate.
- Specific ions can pass through now.
Which body system relies heavily on ligand gated ion channels?
The nervous system:
– released neurotransmitters bind as ligands to ion channels on
target cells to propagate action potentials
Why type of toxin disrupts the cAMP pathway?
Cholera toxin
Where are calcium ions in high concentration and in low concentration?
- High would be ER
- Low would be cytosol
What are the three main processes of cell signalling?
- Reception , 2. Transductions 4. Response
Where does this specificity come from?
3D molecular shape of the proteins involved
Give examples of Receptors for water soluble molecules and Receptors for lipid soluble molecules and find the difference of the two.
Receptors for water soluble molecules are membrane bound and include G Protein Coupled Receptor, Receptor Tyrosine Kinase, ligand-gated ion channel. lipid soluble molecules are NOT membrane bound and include testosterone, estrogen, progesterone, thyroid hormones bind to receptors within the cytoplasm and move to nucleus as a complex.
Explain the process of gated channel through GPCR.
The activated protein is
phospholipase C which then
cleaves PIP2 (a phospholipid) into
DAG and IP3
IP3 diffuses through cytosol and
binds to a gated channel in the ER
Calcium ions flow out of ER down
concentration gradient and activate
other proteins towards a cellular
response
Why so many steps?
Amplifies the response
Provides multiple control points
Allows for specificity of response
temporal
spatial
despite molecules in common
Allows for coordination with other signaling pathways
Why is turning off so important?
All of the signals are for a limited time: activation usually promotes the start of
deactivation, so that signalling is of short period of time, ensuring homeostatic equilibrium.
What does phosphodiesterase (PDE) do?
It breaks down cAMP into AMP, which stops the signal.
So: More PDE = less cAMP = less signal
Caffine blocks PDE which results in cAMP stimulating the cell longer.
