Lecture 13 Flashcards
What is the name for a harmful substance?
Toxins or poisons
What is the name for a beneficial substance?
Medicines or drugs
Can a substance be both a medicine and a toxin?
Yes
How can a substance act as both a medicine and toxin?
Dependant on the dosage and route of administration
What are the four common steps in drug response?
The chemical substance travels from source, interact with target protein through binding or reception, binding even affects the protein either activating or inhibiting it, this leads to a functional cellular response
What is a receptor?
A cellular protein that controls chemical signalling between and within cells
What can receptors control?
Many important physiological processes including sight, smell and taste
What are the key differences between enzymes and receptors?
Enzyme:
One active site, binds substrate which is changes into product
Receptors
Several binding sites, bind ligands which they release unchanged
What are the key similarities between enzymes and receptors?
Can be membrane-bound or free in cytosol, can both be activated and inhibited, and used as drug targets
What are the three main classes of receptor?
Ligand-gated ion channel, G protein-coupled receptor (GPCR), Receptor tyrosine kinase (RTK)
What is the general term given to a chemical substance that specifically binds to a receptor?
A ligand
What are the two forms of ligans?
Endogenous and exogenous
How do ligands trigger a response?
Through a physical binding event and chemical contact
Where are most receptors found?
On the outer cell membrane
What do the receptors detect
Changed in external environment to activate a change in internal environment of a cell
What is the specificity between ligands and receptors?
The pairing must be correct for binding to occur (size and shape)
How do drugs mimic endogenous ligands?
By having the same or very similar chemical structure to meet the specificity of the receptor
A ligand that binds to a receptor causing activation is called a what?
Agonist
What happens to a receptor when an agonist binds?
Undergoes a conformational change
What does activation of a receptor cause?
Signal transduction
What is signal transduction?
A chain of events where messages are passed on through the cell to cause a cellular response
A ligand that binds to a receptor and prevents activation is called a what?
Antagonist
How does an antagonist work to inhibit activation?
Creates competition, blocking the ligand from binding as it has already bound
What does not occur in terms of a cellular response with inhibition?
Signal transduction
