Controlling Signal Response Flashcards
What is a modulation response?
It is when the same signal can cause different kinds of responses in cells.
Give an example of a modulating response molecule?
Acetylcholine (ACh)
Give examples of cells that Acetylcholine targets, and what are their responses?
Ex of Acetylcholine targets:
- Heart Pacemaker cells: Response = decrease rate of firing
- Salivary Gland Cell: Response = Secretion
- Skeletal Muscle Cell: Response = Contraction
Morphogen -
Is a substance governing the pattern of tissue development in the process of morphogenesis, and the positions of the various specialized cell types within a tissue.
What is the Morphogen Gradient?
It is when different concentrations of a morphogen can control cell differentiation.
Ex:
High concentration of Morphogen = makes A cells
Low concentration of Morphogen = makes C cells
How can very small changes in signal concentration make such huge changes in cellular response?
Co-operativity
Only at a certain concentration of signaling ligands can a specific protein complex be formed that will trigger a huge cellular response.
Positive Feedback -
It is an all-or-nothing response and the product facilitates more activity from the enzyme. A positive loop.
At low [ligand] there is no enzyme activity, no cell response
At high [ligand’ there is massive enzyme activity and a cellular response
Negative Feedback -
The product of the cell or enzyme stops the activity of the enzyme.
What characteristic of Signaling ligands allows them to be controlled more efficiently?
A short half-life. With a short half life, they won’t last too long in the cell, and they won’t wreak havoc on the cells enzymes for long periods of time.
Describe the cell response of skeletal muscle from Acetylcholine signaling.
- Acetycholine activates Nitric oxide (NO) synthase.
- Arginine is converted to NO, and excreted.
- NO activates guanylyl cyclase in target cells: converting GTP to cGMP
- cGMP causes muscle relaxation
Scaffold protein -
A scaffold protein has a string of inactive intracellular signaling proteins bound to it. Once a signaling molecule is present, it flows down the scaffold protein in a cascade, activating each protein down the scaffold.
What is a signaling complex?
A scaffold protein coupled with a extracellular receptor, that performs signaling cascades.
