Cell Signalling Flashcards
Why are multi-step transduction pathways advantageous?
- Amplifies the signal since each molecule can transmit the signal to other molecules
- More opportunities for control
What are kinases?
Enzymes that phosphorylate molecules
What are secondary messengers?
Small molecules that help relay the signal
What is considered the primary signal messenger?
The ligand
What are examples of secondary messengers?
- Cyclic AMP
- Calcium ions
Why doesn’t a 1:1 ratio from the receptor to the cellular response work?
It isn’t fast enough for cells to respond to changing conditions. It takes time for molecules to randomly come together and interact
What is signal amplification?
At each step, many signalling molecules are activated, which then activates many molecules of the next step…(domino effect)
Why are signalling pathways important?
- They initiate gene expression
- Regulate metabolic pathways
- Open ion channels
- Regulate protein activity
Can signalling pathways branch and interact?
Yes. A specific ligand can activate a receptor in a different cell type to give multiple responses
What is cross talk?
Two different ligands that activate two different receptors can increase or inhibit one another when they are activated
Can ligands activate a different receptor in a completely different cell, and elict a different response?
Yes
What do signal transduction pathways allow for?
- Rapid signalling from hormones
- Amplification of the signal
- Different cell types respond to signalling differently
What are scaffolding proteins?
Proteins that hold pathways and networks together for better efficiency: Less distance to travel, enhances speed and accuracy
What is the most common part of the body that uses scaffolding proteins?
Brain signal transduction pathways
How do signalling pathways end?
GTP is converted to GDP, to turn off the G protein
cAMP is converted to AMP
Protein phosphatases inactivate the phosphorylated kinases and other proteins
No more signal, no more cell response
