Cell-Cell Communication 1 Flashcards
What is a Ligand?
Substance that forms a complex with a biomolecule to serve a biological purpose.
What are Extracellular Signal Molecules?
Ligands that can act over short or long distances. Also called First Messengers.
What does a Neurotransmitter do?
Transmits signals across a chemical synapse- from neuron to neuron, neuron to muscle cell, or neuron to gland cell.
What is a Receptor?
A protein molecule that receives chemical signals from outside the cell.
Where are receptors typically located?
On the cell surface, or inside the cell- nucleus or cytoplasm.
T/F: On the cell surface, the signal molecules are hydrophilic.
True.
T/F: Inside of the cell contains hydrophobic signal molecules.
True.
What are the 3 major types of cell surface receptors that we discussed?
- Ligand-Gated Ion Channel Receptors
- G-Protein Coupled Receptors
- Enzyme Coupled Receptors –> RTK
What are Second Messengers?
Intracellular signaling molecules generated in large amounts in response to receptor activation.
T/F: There are many second-messenger systems in animal cells.
False; few.
Which second messenger(s) are located in the cytoplasm and are hydrophilic?
IP3, cAMP, Ca 2+
Which second messenger(s) are located in the plasma membrane and are hydrophobic?
DAG
What is a Molecular Switch?
Proteins that help relay the signal into the cell by either generating second messengers, activating the next signaling or effector protein in the pathway.
When they receive a signal, molecular switchers switch from an active state to an inactive state until another process switches them off.
False; inactive to active.
What are the most important molecular switchers?
Protein Kinase ( Serine/ Threonine Kinases & Tyrosine Kinases), Protein Phosphatase, GTP- Binding protein.
What does the kinase enzyme do?
Modifies proteins by phosphorylating them.
What does the enzyme protein phosphatase do?
Responsible for dephosphorylation, opposite direction of protein kinase enzyme.
What does GTP-Binding protein do?
Switch between an “on” state when GTP is bound and “off” state when GDP is bound.
What do GAPs (GTPase-activating proteins) do?
Drive the proteins into an inactive state, increase hydrolysis of bound GTP.
What do GEFs (Guanine Nucleotide Exchange Factors) do?
Activate the proteins, release bound GDP.
