Cell Communication Flashcards
Cell Communication allows for
Allows for cells in a multicellular organism (and unicellular organisms) to coordinate their activities
Cells communicate with each other via
chemical signals
Unicellular organisms in tough conditions
Example?
Can use cell communication to come together and form multicellular organism (fruiting bodies)
Why is cell communication important in organisms like Sacharomyces cervisae (Brewers yeast)
Because there are 2 sexes. a and alpha.
They use chemical messengers to identify members of the opposite sex.
Each has receptors for the opposite sex’s’ messengers
Chemical messenger
Aka Ligand
Biomolecule that acts as a message/does the signaling
Receptor
Protein
Binds with a specific Ligand/Chemical Messenger
A cell can only respond to a messenger
If it has the matching receptor
2 ways of direct contact cell communication
Cell Junctions
Cell to cell recognition
Cell junction(2 kinds)
Plasmodesmata in plants
Gap junctions in animals
Cell to cell recognition
When the glycoprotein of one cell binds to the receptor of another cell
Local signaling 3 steps
1) Secretory cell makes and secretes CM
2) CM diffuses
3) Target cell with the right receptors responds to the CM
Paracrine signaling
When the target and secretory cell are in the same area/close proximity
Synaptic signaling
Done by neurons
Secretes CM (called a Neurotransmitter) in a local area to a target cell
Distance signalling
Secretory cell= Endocrine cell
Ligand/CM= Horomones
Endocrine cell synthesizes and secretes horomones
Horomones travel in ___ signaling via the
They will only bind with
Distance
The bloodstream
Cells with the right receptor (target cells)
Is Distance signaling used in plants?
Yes
3 phases of cell signaling
Reception
Transduction
Response
Reception
Ligand binds to receptor (transmembrane protein)
Transduction connects
What initates transduction
Connects reception and cell response
Receptor initiates transduction pathway (molecule relay)
Response involves the
Activation of target cell response
Tyrosine kinase
- Ligand binds to receptor.
- Causes dimerization (2 fusing together).
- Self phosphorylation occurs (Gets 6 phosphates).
- Relay protein is activated by the Phosphate.
- Causes cell response.
Tyrosine
Receptor part
Kinase-
The enzyme that phosphorylates
G protein coupled receptor 6 steps
1.Ligand binds to inactive G protein coupled receptor
2. Receptor is activated. Causes G protein to bind.
3. GDP falls off. Replaced by GTP.
4. Signal molecule is released
5. Cell response activates, GTP goes off to activated enzyme (or sum else)
6. G protein released as GDP+P
Ligand gated ion channel
- Ligand binds
- Gate opens and diffusion occurs
- Cell response occurs
- Ligand leaves and gate closes
3 transmembrane receptors
Tyrosine kinase
G coupled protein receptor
Ligand gated ion channel
Transcription factors
Proteins that influence transcription and gene expression
In addition to transmembrane receptors there are also
How do they work? 5 steps
Intracellular receptors
Inactive In cytoplasm (not plasma membrane)
Bind with hydrophobic ligands (lipids)
Forms hormone receptor complex
Causes it to go through nuclear pores
Acts on dna (turns genes on/off)
Intracellular receptors are also
Transcription factors since they act on rna production
Signal transduction converts
Converts signal outside the cell into a form that can bring about a cell response
Signal transduction is usually a ___ process that involves one or more of the following
(Multistep)
protein phosphorylation/Dephosporylation
change in second messenger concentration (small molecules/ions)
PP
Phosphitase
Takes off a phosphate
How does signal transduction use phosphorylation/dephosphorylation
Ligand binds activating relay molecule Which activates Protein kinase
Takes second PK and adds Phosphate
Activates second PK
Same process for third
Activates protein+cell response
Change in second molecule concentration
cAMP
Gprotein activates Enzyme Adenylyl Cylcase
Adenylyl Cyclase takes 2 phosphates off ATP
Signaling molecule cAMP is made
cAMP acts on protein->cell response
Enzyme phosphodiasterase turns cAMP into AMP
Calcium ion concentration? Due to?
Change is second messenger concentration
High Ca+ outside cell, in smooth ER, mito matrix.(Happens due to calcium pumps)
IP3 and Calcium are both ____ in the ____
Secondary messengers in the transduction pathway
Where does response occur
Can occur in nucleus via control of gene expression(turning on/off)/transcription
Can also occur in cytoplasm
Apoptosis
Cell death
When receptor for death signaling molecule binds with ligand
Leads to apoptosis
Regulation of response (2 kinds)
1) Signal Amplification (due to enzymes)
One receptor can activate many proteins->x100 cAMP
2)Coordination/regulation with other pathways
4 ways cell can respond to same signaling molecule
1) pathway lead to a single response
2) pathway branches leading to 2 responses
3) crosstalk occurs between pathways
(Another transduction pathway activates/inhibits the first)
4)Different receptor leading to different response
How is IP3 produced and What does it do
Gprotein activates phospholipase C which Produces IP3
IP3 binds to gated calcium channels
Opens the gate
ATP is used to pump calcium and create gradient
Cellular Response can occur in the ____ and the _____.
Nucleus and cytoplasm
In nucleus cell response controls transcription/gene regulation
