Cell Signaling 1 Flashcards
What kind of signaling is this? How does it work?
What kind of signaling is this? How does it work?
What kind of signaling is this? How does it work?
Define what a ligand is.
A signaling molecule.
A molecule that binds to another specific molecule, usually a receptor on a cell, to trigger a cellular response, essentially acting as a chemical messenger that transmits signals between cells within an organism.
Ligand = Key
Receptor = Lock
What are second messengers?
Intracellular signaling molecules.
Can you fill in the blanks?
Receptor binding initiates __________ inside the cell.
Signal transduction
What is the concentration of calcium in a cell?
About 100nm or 0.0001 mM
Why is calcium kept low in the cell?
Because calcium is an important second messenger.
How was calcium kept low in the cell?
Through Ca++-ATPases that pump calcium out of the cell or into the endoplasmic reticulum. (or sarcoplasmic reticulum in muscle cells.)
What are the two ways calcium concentration in the cytosol can increase?
- Ca++ can enter via a membrane calcium channel(from outside the cell to inside).
- Ca++ can be released from intracellular stores. (Endoplasmic reticulum or sarcoplasmic reticulum.)
What is Calmodulin? How does it work?
A ubiquitous Ca++ binding protein.
Besides calmodulin what are two other important Ca++ binding proteins? What do they do?
Troponin (regulation of skeletal muscle contraction)
Proteins involved in exocytosis
Test: fill in the blanks.
True or false: all receptor proteins are found on the membrane. If false, name the types.
False: most are(polar signaling molecules), BUT some can diffuse across the membrane(Nonpolar signaling molecules)
Polar= Cell membrane receptor
Nonpolar = Intracellular Signal Receptor
Where is the receptor for a lipophilic signal molecule?(2)
- In cytosol
- In nucleus: Nuclear receptors
They are intracellular receptors!
What are the categories of membrane receptors? (3)
Nuclear receptors function as a ligand-activated transcription factors. Explain what that means.
Ligand is signal, receptor is transcription factor. So when ligand binds to nuclear receptor it changes gene expression.
Nuclear receptors have a characteristic modular structure. What is it?
Test: fill in the blank
Can you name all 8 Nonpolar hormones that signal via intracellular receptors. (They are all Nonpolar )
Explain how ligand-gated ion channels work. What’s the usual signaling molecule?
Binding of the signaling molecule opens the channel, creating a change in membrane potential that occurs within a few milliseconds.
This is the signaling mechanism that underlies fast synaptic transmission.
Usually a neurotransmitter is the signaling molecule.
Test: fill in the blanks and what type of channel is this?
Ligand gated ion channel.
Test: fill in the blanks. What ions increase hyperpolarization? depolarization?
Test: fill in the blanks.
G-Protein Knowledge: what it is made of.
G-Protein Knowledge: how it functions.
Test: fill in the blank.
Test: G-Alpha, fill in the blank.
cAMP activates protein kinase A (PKA). Why does this matter?
The GPCR signal is terminated at several steps. What are the steps?
Do you know how cholera works?
Adding on: increased fluid secretion is because CFTR is open too often due to phosphorylation, meaning ions go out of cell into places like GI tract. Meaning water follows suit(through osmosis), leaving your body.
cAMP can do more than work through protein kinase A. What else can they do? Give an example of how it occurs? Hint: Golf.
It can change membrane potential and act as a ligand to open ion channels.
