Topic 5 - Intro to Cell Signalling Flashcards
In order for cells to be able to differentiate systematically, cells need this ability
Ability to communicate with each other
What steps are key in proper signalling between cells?
- Initiating a signal
2. Terminating a signal
What are the 3 general effects signalling pathways can exert on cells?
- Induce changes in the cytoskeleton (shape/movement of the cell)
- Alter gene expression
- Affect cellular metabolism
What kinds of cells are able to communicate via signalling? (e.g. prokaryotes, eukaryotes, unicellular, multicellular…)
All cells
In S. cerevisiae (yeast), when mating factors are released, this induces the formation of this protrusion [name]
Shmoo
Describe the makeup of a gap junction
Gap junctions made of 2 hemichannels called CONNEXONS, each connexon is made of 6 CONNEXINS
What can be exchanged through gap junctions?
Water, small water-soluble molecules, inorganic ions
Gap junctions are common in this kind of cell
Animal cell
What is the plant equivalent of a gap junction?
Plasmodesmata
Are all cells connected to each other via gap junctions?
No
In what 3 ways are signalling molecules released into the extracellular space?
- Exocytosis
- Diffusion (when the molecule is hydrophobic)
- Stay attached to the membrane but project out of the cell extracellularly
Describe how cells economize their signalling molecules
Different combinations of signalling pathways produce specific results, therefore fewer individual signalling molecules are required
When a cell receives no signals, what does it do?
Undergoes apoptosis
Small hydrophobic signalling molecules tend to bind to this kind of signalling receptor
Nuclear receptor
Small hydrophobic signalling molecules are transported outside the cell bound to…
Carrier proteins
Hydrophilic signalling molecules bind to this class of receptor
Cell surface receptors
How many kinds of nuclear receptors have been identified in humans?
48
What are the 3 domains of a nuclear receptor?
- DNA-binding domain
- Transcription-activating domain
- Ligand-binding domain
What is an orphan nuclear receptor?
A nuclear receptor for which the ligand is unknown
Active nuclear receptors are often bound to this kind of protein
Coactivator proteins
Do nuclear receptors always activate gene transcription?
No, sometimes they repress it
Describe where nuclear receptors are when not active
Can be in cytosol, nucleus, already bound to DNA
What are the 3 major classes of cell surface receptors?
- Ion channel-coupled receptors
- G-protein-coupled receptors
- Enzyme-coupled receptors
How does a cell surface receptor work, briefly
Ligand binds to extracellular receptor which induces a change on the intracellular side of the cell, initiates a signal transduction cascade
