Explain the 4 types of chemical cell signals
Autocrine
Juxtacrine
Paracrine - all local
Endocrine - distance
Explain the 3 processes for cell signaling
Reception - target cell detection
Transduction - transd
...
Explain the 4 types of chemical cell signals
Autocrine
Juxtacrine
Paracrine - all local
Endocrine - distance
Explain the 3 processes for cell signaling
Reception - target cell detection
Transduction - transduction pathway
Response
Explain crosstalk
Interrelation of signal transduction pathways
Multiple pathways can converge
Pathways can branch; a protein can activate multiple pathways
Explain ligands
Chemical signal molecules; very specific;
Agonists - same effect as ligand (adenosine)
Antagonist- inhibitor (caffeine)
Explain the concept of dissociation contant
Measure of the affinity of receptor for its ligand
Lower Kd, greater affinity
Essential for drug dosage prescriptions - drugs function as ligands
Explain cell surface receptors
receptors found in the plasma membrane
For large or polar ligands (insulin)
Examples: proteins, peptides, amino acids, nucleotides
What are intracellular receptors?
lipid soluble. they can cross cell membranes of target cells directly.
For small or non polar ligands that can diffuse across the cell membrane
Examples: Steroid hormones, retinoids, vitamin D, NO, CO
They respond to signals like light or chemicals that can cross the cell membrane. Many are transcription factors. (Alter gene expression in DNA)
List the 3 types of cell membrane receptors in eukaryotes and explain how they work
Ion channels - allow ions to leave/enter, example: acetylcholine receptor in muscles
Protein kinase receptors - catalyze phosphorylation of themselves and/or other proteins
G protein-linked receptors - signal binding to receptor activates a G protein, which then activates an effector protein
G-protein-linked receptor
G protein-linked receptor—> inactive G protein —> inactive effector protein
Forms GTP from GDP
Activated G protein does its ting
GTP is hydrolyzed to GDP
What does signal transduction cascade do? Explain second messengers
Transmits and amplifies a signal inside a cell
Second messengers can transmit and amplify signals within a cell
In a protein kinase cascade, one protein kinase activates the next, and so on.
What is Ras?
It is a G-protein that regulates cell division
Abnormal form of it is found in cancer cells. It is permanently pound to GTP, causing continuous cell division
Ras inhibitors stop the cell from dividing
What happens in a protein kinase cascade?
Signal amplified at each step
Information that arrives at the cell membrane is communicated to the nucleus
Multiple steps happen
Different target proteins react
What are second messengers?
small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion.
They amplify and distribute the signal, and are involved in crosstalk.
examples of second messengers
cAMP, calcium ions, cGMP, NO
cAMP is made from ATP by adenyl cyclase
Lipid-derived second messengers: IP3 and DAG from PIP2
Ca2+ ion channels can also be second messengers. They activate protein kinase C (PKC) and stimulate secretion by exocytosis
Nitric oxide is a second messenger between acetylcholine and the relaxation of smooth muscle in blood vessels, allowing more blood flow
[Show More]
