Flashcards in Test 3 week 7 Deck (222)
How does a cell respond to an extracellular molecule and take on a group of different functions?
What happens once an extracellular molecule attaches to a receptor?
You can have a group of intracellular proteins that signal each other and in the end you're going to have effects carried on by effector protein. This can lead to a change in cellular metabolism, gene expression, or in cell shape or MVMT by effecting certain cytockeleton proteins
What are the two things that extracellular signal molecules bind to?
Cell-surface receptors or intracellular receptors
What happens when a extracellular signal molecule binds to the cell-surface receptor?
The signaling molecule binds to the protein, and once it binds to the protein it undergoes and group different of different effects and action in the cell
What happens when a extracellular signal molecule binds to the intracellular receptor?
A signal can diffuse into the cell, into the nucleus, then binds to the cell carrying on its effect there. For a signaling molecule to travel across the cell membrane without needing a receptor, it has to be lipid soluble or hydrophobic.
Why is there a carrier protein present when a extracellular signal molecule binds to the intracellular receptor?
Because the the signal cannot travel in the plasma by itself, due to it being hyrophobic
What are the four forms of intercellular signaling?
- Contact dependent
What is contact-dependent intercellular signaling?
A signaling molecule that is bound to the cell membrane of a cell and there is a receptor for that signaling molecule on another cell. Because the cell is bound to the cell membrane, it therefore cannot contact the receptor unless the 2 cells get in contact themselves physically. Once this happens all the different effect of cell signaling can be done
What is synaptic intercellular signaling?
A neuron can release a neurotransmitter that effects a target cell which is the cell that is in direct contact with that neuron
What is endocrine intercellular signaling?
An endocrine cell somewhere in the body can secrete a hormone, which can then travel down the blood stream and effect a target cell somewhere that is completely or not in close proximity to the endocrine cell
What is paracrine intercellular signaling?
A cell secretes a mediator that only works in the immediate vicinity of the cell, local mediator. it only effects the target cells that are directly around the signaling cell
What is the contrast between endocrine and neuronal/synaptic long-range signaling?
Endocrine signaling is spread throughout the blood stream while synaptic is more specific and presice
____ cells dump their hormones into the bloodstream and these hormones travel and they can affect cells throughout the entire body. There's no specificity. Meaning that the hormone is evenly distributed throughout the blood stream and is evenly distributed throughout the different cells in the body. However there is specificity because the only cells that are going to be able to respond to that hormone are cells that have the right receptor
Endocrine cells can communicate and carry on ____ functions, but they to have ___ different hormones in order to communicate
Endocrine cells can communicate and carry on *different* functions, but they to have *different* different hormones in order to communicate
_____ signaling is a lot more specific, not wide spread. The hormone is not secreted or evenly distributed around the body. Each hormone synapse a specific cell or cells as a result, you can have the same neurotransmitter secreted by different neurons and each one of them can carry on different function. So neuronal cells can communicate differently, even though they're using the same neurotransmitters while endocrine cells cannot
Hormones can carry their functions through ___ responses and ____ responses. Some hormones can do both
Hormones can carry their functions through *fast* responses and *slow* responses. Some hormones can do both
Signals and hormones can also stimulate _____ and ____, then proteins modification synthesis, then alter cytoplasmic machinery which will alter cell behavior. Here you are building something new and this takes time. These hormones usually take a little longer to act
Signals and hormones can also stimulate *gene transcription* and *translation*, then proteins modification synthesis, then alter cytoplasmic machinery which will alter cell behavior. Here you are building something new and this takes time. These hormones usually take a little longer to act
The same signaling molecule can cause ____ effects and the cells can respond ____ to the same signal. Usually because the different receptors can cause a ____ effect and each of these cells have a ____ receptor
The same signaling molecule can cause *differently* effects and the cells can respond *differently* to the same signal. Usually because the different receptors can cause a *different* effect and each of these cells have a *different* receptor
ACh can also cause secretion through the ____
ACh through the effects on the heart muscle cell can stimulate a different receptor, and through that different receptor it can actually cause ____ and____ contraction.
ACh through the effects on the heart muscle cell can stimulate a different receptor, and through that different receptor it can actually cause *relaxation* and *decreased* contraction.
In skeletal muscle we have nicotinic receptors and in the heart we have ___ cells that can carry on different functions.
ACh is released through the ___ in the heart muscle cell and it can slow down the SA node
What are the 3 main classes of cell surface receptors?
- Ion channel- coupled receptors
- G- protein- coupled receptors
- Enzyme- coupled receptors
How can positive feedback work?
You have an inactive enzyme, it binds to a signaling molecule and once it binds to the molecule, it can then start working on it's substrate. It works on its substrate and produces a product that can bind to the enzyme causing a conformational change therefore enhancing activity on the enzyme to actually work a lot better than it has. Once the enzyme is activated through the signal, it can increase its own function and activity through its own product
What are the different ways that cells can adjust their sensitivity to a signal?
- Receptor sequestration
- Receptor down-regulation
- Receptor inactivation
- Inactivation of signaling protein
- Production of inhibitory protein
How do receptor sequestration adjust a cell's sensitivity to a signal?
Once some form of modification happens this receptor can stimulate the endocytosis of the receptor which can then be stored in the endosome and once stored in the endosome it can be released at another time
How do receptor down-regulation adjust a cell's sensitivity to a signal?
It can be stored in a lysosome and be degraded or broken down
How do receptor inactivation adjust a cell's sensitivity to a signal?
Most easiest. In which a protein or some form of modification happens to a receptor and once it happens the receptor can no longer carry on its signal. It has been blocked
How do inactivation of signaling protein adjust a cell's sensitivity to a signal?
We can block downstream proteins. The signal can still be active, but we're blocking a downstream protein and therefore eventually inactivating the whole signaling cascade, because once you breakdown a step, any downstream steps are also inhibited