1 - Interpreting Extracellular Signals & Signal Transduction Flashcards
What does signal transduction involve (two basic components)?
A signal in, and a signal out
For signal transduction, what is the most common and general kind of input signal?
Extracellular signaling molecule
For signal transduction, what is the most common and general kind of output signal?
Intracellular signaling molecule
What questions are involved in signal transduction (in terms of the signals) (4 general questions)?
- How are signals generated and released?
- How are signals perceived by the recipient?
- How is the response to the signal generated?
- How are multiple signals integrated?
What questions are involved in chemical messengers (3 general questions)?
- How does it mediate a response in a particular cell type?
- How does it mediate pleiotropic responses? (different effects by same chemical messenger)
- How does it mediate different responses in different targets?
How can chemical messengers be regulated (general mechanisms)?
Synthesis, packaging, secretion, and degradation
Why is cell signaling important?
Controls almost every aspect of cell structure and function, need to respond to environment, etc.
What processes does cell signaling regulate?
Growth and division
What field of biology was useful for studying cell signaling?
Virology
Why is virology useful for studying cell signaling?
Viruses need to infect cells to function, so by studying viruses, we learned about the basics of cells
What are some examples of extracellular signals?
Hormones, pheromones, heat, cold, light, osmotic pressure, concentration changes of glucose, K+, Ca2+, cAMP
What are some examples of intracellular signals?
Modification of metabolism, production and degradation of substances, phosphorylation, activation and inhibition of reactions
What are the 5 general principles of cell signaling?
- Signals act over different ranges
- Signals have different chemical natures
- The same signal can induce a different response in different cells
- Cells respond to sets of signals
- Receptors relay signals via intracellular signaling cascades
What does it mean that signals act over different ranges?
Different spatial capabilities of the signals (local vs endocrine, etc.)
What does it mean that signals have different chemical natures?
Different structures of the different signals lead to different functions
How can the same signal induce a different response in different cells?
Different receptors and relay cascades (found in different cells) can cause a different output based on a signaling input
What does it mean that cells respond to sets of signals?
The cell integrates multiple signals over space and time to produce a particular response
What is the advantage of relaying signals via intracellular signaling cascades?
More amplification, which allows for a large response from a small amount of signaling molecule
What do sensors do?
Detect the external signals in the environment
What do the internal logic circuits do?
Responds to the inputs, and decided what is the proper response
What do actuators do?
The final step in the pathway to produce a response (cell movement, growth, chemicals, etc.)
Why is timing important in cell signaling?
Different responses could need a fast or slow response, a sustained response, or a degrading response. Thus, the timing is important based on the stimulus
What is the time scale of altering protein function?
Fast (sec to min)
What is the time scale of altering gene expression?
Slow (min to hour)
Why is altering protein function fast?
Proteins are already in the cytoplasm to be modified
Why is altering gene expression slow?
Need all the machinery to create new proteins and alter protein levels
What is the range of endocrine signaling?
Long range (through bloodstream)
What is the range of paracrine signaling?
Local (close neighbors)
What is the range of neuronal or synaptic signaling?
Synapse of two neurons or other cells
What is the range of cell-cell recognition?
Direct contact
What are some examples of endocrine signaling molecules?
Estrogen, epinepherin
What are some examples of paracrine signaling molecules?
Nitric oxide, histamines, prostaglandins
What are some examples of neuronal signaling molecules?
Neurotransmitters (GABA, dopamine, etc.)
What are some examples of cell-cell recognition signaling molecules?
Delta/notch
What is autocrine signaling?
A cell releases a signal, which can bind to its own receptors and cause a response
What does acetylcholine do to heart pacemakers cells?
Decreases rate of firing
What does acetylcholine do to salivary gland cells?
Secretion of chemicals in vesicles
What does acetylcholine do to skeletal muscle cells?
Contraction
How can acetylcholine lead to different responses in heart, salivary, and skeletal muscle cells?
Different detection (receptors) and intracellular cascades (downstream signals) lead to different responses
What are some examples of classes of extracellular signals?
Small molecules, gases, steroids, eicosanoids, peptides
What are some examples of receptor types?
G-protein coupled receptors (GPCRs), receptor protein-tyrosine kinases (RTKs), ligand gated channels, steroid hormone receptors, specific receptors (B and T cell receptors)
What are some examples of small molecules as extracellular signals?
Amino acids and their derivatives, such as acetylcholine, epinepherine, and dopamine
What are some examples of gases as extracellular signals?
Nitric oxide (NO) and carbon monoxide (CO)