Chapter 7.2.1 (Exam 4) Receptors Flashcards
Receptors Bind Signals to Initiate a Cellular Response (10 cards)
What are ligands?
Chemical signal molecules
How do ligands not bind to any receptors?
Receptor proteins have very specific binding sites for ligands
The ligand fits into a three-dimensional site on its receptor and causes the receptor protein to change shape
The binding is reversible, and the ligand is not altered
What else can bind to receptors aside from ligands?
Agonists and antagonists
What are agonists?
Agonists have the same effect as the ligand
What are antagonists?
Antagonists (inhibitors) bind to the receptor, preventing the ligand from binding, but not setting off signal transduction
Is caffeine an agonist or an antagonist? Why?
Antagonist
Blocks adenosine receptors from binding to adenosine, which reduces brain activity and wakefulness
What are two types of receptors, classified based on where they are located?
Membrane receptors and intracellular receptors
What do membrane receptors bind to?
Large or polar ligands (e.g., insulin) bind to cell membrane receptors
What do intracellular receptors bind to?
For small or nonpolar ligands that can diffuse across the cell membrane (e.g., estrogen)
How come polar molecules use membrane receptors and nonpolar molecules use intracellular receptors?
Nonpolar molecules can diffuse across the cell membrane, but polar molecules cannot
