Final Exam Flashcards
Classify the types of substances/ agents that can act as cellular signal
What are the different classes of hormones?
- small water-soluble molecules (amines, epinephrine, histamines, dopamines)
- peptides (insulin and gastrin)
- lipids and lipophillic molecules (estrogen, thyroxine, vitamin D)
what are cytokines?
a group of peptide molecules produced by particulary cells of the immune system. These include peptides, interferons, interleukins, growth factors, and tumor-necrosis factor.
Describe the characteristics of a good signal.
- perception of the signal - mediated by cell surface or in some cases intracellular receptors
- specificity - only one or only a limited number of receptor type(s) recognizes the signal
- response- the receptor binds to the ligand and conveys a message
- termination - the signal is switched off (dephosphorylation, degradation, sequestration of calcium)
What are the two groups of neurotransmitters?
Small molecules: GABA, DA, and ACh
hormones moonlighting as neurotransmitters: epinephrine, histamine, neuropeptides, substance P, and endorphins
What is the difference between agonist and antagonist?
an agonist will allow for full activation; an antagonist will block the action of the neurotransmitter and therefore have no activation
Desensitization
occurs when a receptor is in the continued or frequent presence of an agonist and ceases to respond to binding of the ligand
there is an initial rapid response but as the ligand is reapplied, the r
Explain the B2-adrenergic receptor/ BARk pathway
- adrenergic receptor (epinephrine) will bind to the B-adrenergic receptor
- this will lead to the activation of a g protein that will activate adenylate cyclase
- adenylate cyclase will transfer ATP to cAMP
- this will activate protein kinase A
- PKA will phosphorylate BARK
- Bark will phosphorylate the receptor
- this will attract B-arrestin which will stop the receptor from interacting with downstream proteins and terminate the response
Characteristics of G-protein Coupled Receptors
- consist of 7 transmembrane domains
- coupled to g protwins (aby subunits that hydrolyze GTP)
- can have their activity modified by RAMPS (receptor-activating modifying proteins)
Ligand-gated ion channels
group of transmembrane ion channels that are opened or closed by binding of a specific extracellular or intracellular ligand/neurotransmitter
- result is a rapid change in the membrane potential of the cell
What is the difference between ionotropic and metabotropic?
ionotropic = when ligand binding results in direct opening of the channel
metabotropic = when ligand binding to a receptor activates other signaling pathways resulting in activation of the channel.
what are the three amino acids that phosphorylation takes place on?
serine, threonine, and tyrosines
Explain the hydrolysis of GTP to activate/inactivate.
- GEF will facilitate the exchange of GDP for GTP.
- GAP will hydrolyze the bound GTP back to GDP
- GTP means active/ GDP is inactive
