Chapter 14 Flashcards
Ligand
Small messenger molecules
Second Messengers
Molecules produced in the target cell that relay the message from one part of the cell to another
Receptor Affinity
How easy it is for a ligand to bind to its receptor
Kd
Dissociation constant- how much ligand is needed to trigger a response (low Kd = high affinity)
What is the relationship between Kd and receptor affinity
Inverse
Receptor-Down Regulation
when receptors are bound to ligand for long periods the cell no longer responds to stimulus
Receptor Mediated Endocytosis
receptors on cell surface are internalized
Desensitization
receptor decreases its affinity for ligand
Antagonist
inhibit the receptor by blocking the natural ligand from binding
Agonist
drug that activate a receptor (morphine mimics endorphins)
What are the pharmaceutical applications of cellular receptors?
synthesis of artificial ligands
G-Protein Linked Receptors
family of receptors in which ligand bonding causes a change in conformation that activates a G-protein
Protein Kinase-Associated Receptors
receptors are protein kinases, ligand binding activates the enzyme to add a phosphate group, causing phosphorylation events
Protein Kinases
enzyme that adds a phosphate group
What is the structure of G-protein linked receptors
7 transmembrane alpha helices
Structure of Tyrosine Kinases
single polypeptide with 1 transmembrane domain
Activation of Tyrosine Kinases
ligand binds and the receptors phosphorylate each other’s tyrosine residues
What is Cyclic AMP?
ATP that has had the last two phosphates cut off and the remaining one is linked back to the sugar
caused by adenylylcyclase
What is Cyclic AMP degraded by?
phosphodiesterase
Growth Factors
ligands that can tell a cell to grow and divide
What is epinephrine also known as?
Adrenaline
What does insulin control?
blood glucose levels
What do epinephrine and norepinephrine control?
Fight or flight
relaxes smooth muscle and diverts blood flow to the heart and lungs
Apoptosis
programmed cell seppuku
Caspases
enzymes responsible for protein cleavage
Steps of apoptosis
- volume of cell decreases
- nucleus and organelles break apart
- cell produces blebs
- DNA degraded
- dismantled into apoptic bodies
- remnants engulfed by nearby cells
What two things might degrade the DNA during apoptosis
endonuclease and DNAase
What is something that might eat parts of a cell after it commits apoptosis?
macrophage
Bcl2
anti-apoptic protein on mitochondria’s surface
Cytochrome C
released from mitochondria to promote apoptosis
P53
triggers apoptosis in response to cell damage
Three ways to trigger apoptosis
binding of “death signals” to cellular receptors
withdrawal of survival factors from cellular receptors
DNA damage
what degrades cyclic AMP
phosphodiesterase
