Cell Communication and Signaling Flashcards
Yeast Mating Types
Two types of haploid yeast (mating types)
1) Type a –> Secretes a-factor
2) Type alpha –> Secretes alpha-factor
Type-a yeast
Secretes a-factor
Has receptors for alpha-factor
Type-alpha yeast
Secretes alpha-factor
Has receptors for a-factor
Yeast Mating Process
1) a and alpha yeast cells bind to each others’ particles
2) a and alpha cells begin to fuse
3) creates a new cell with both a/alpha genes
Signal-Transduction Pathway
1) Signal reception
2) Signal transduction
3) Cell response
Types of communication in multicellular organisms (2)
1) Local communication
2) Long-distance communication
Types of local communication (3)
1) Paracrine
2) Direct Contact
3) Synaptic
Direct Contact Communication (and types)
Signals pass through intercellular connections OR through cell-cell recognition
1) Gap junctions
2) Plasmodesmata
3) Cell-cell recognition (involves glycoproteins)
Paracrine Communication
Signals released into the extracellular fluid (Signal is available to all neighboring cells)
–> Signal only impacts those target cells with the necessary receptor
Synaptic Communication
In NEURONS
–> Signals are released into a synapse (region between two neuron terminals)
–> Signal goes ONLY to interact with that one neuron (no other cells can interact with it)
Long Distance Communication (and its one type)
Occurs between cells that are farther apart (usually within an organism) –> BUT it can occur between organisms
1) Endocrine/Hormonal Signaling
Endocrine/Hormonal Communication
Signals are released by an endocrine cell and travel a long distance through a vascular system (or possibly through the air)
–> Only target cells with necessary receptors will respond
Fruit ripening when next to other ripe fruit is an example of…
(and explain its cause)
Long distance communication BETWEEN organisms
–> The ripening agent ETHYLENE (gas) that spreads to other fruits nearby a ripening fruit (gets them to ripen as well)
The ability of a cell to respond to a signal is dependent upon…
Whether it has the specific receptor molecule that can bind a given signal
Main stages of cell signaling (3)
1) Reception
2) Transduction
3) Response
Reception
The detection (by a target cell) of a signal which binds to a receptor molecule –> The RECEIVING of a signal
Receptor
Molecule that a signal binds to
Ligand
Signal Molecule
Main types of receptors (4)
1) G-protein linked receptor
2) Tyrosine-kinase receptor (enzyme receptor)
3) Ligand-Gate Ion Channel
4) Internal/Intracellular Receptor
G-Protein Linked Receptor
Cell surface transmembrane receptor that works WITH the help of G-protein
G-Protein
A protein that binds to GTP
G-Protein Linked Receptor: Extracellular Domain is ________
The receptor: Interacts with the ligand
G-Protein Linked Receptor: Cytoplasmic Domain is ________
Initiator of transduction: Interacts with the G-protein molecule
G-Protein Linked Reception Process
1) No ligand = Inactive state = G-Protein bound to GDP
2) Ligand binds to receptor: receptor changes shape
3) Inactive G-protein binds to receptor which causes GTP to displace GDP
4) Activated G-protein dissociates from receptor and diffuses along membrane
5) G-protein binds to an enzyme, activates it = triggers cascade
6) G-protein hydrolyzes GTP to form GDP and returns to inactive state
G-Protein Active vs Inactive states
Active State = Bound to GTP
Inactive State = Bound to GDP
Enzyme Receptors
Receptors that function as BOTH a receptor and an enzyme
(Not linked to an enzyme, it IS an enzyme)
Tyrosine-Kinase Receptor
Protein kinase receptor that phosphorylates tyrosine
Tyrosine-kinase receptor has ______ subunits
2 subunits
Tyrosine-Kinase Receptor Process
1) Signals bind to receptors of the TKR subunits
2) The subunits dimerize (come together to form one unit)
3) Subunits phosphorylate each other (their tyrosine components)
4) TK receptor FULLY activates
5) Relay proteins bind to the TKR and become activated = begins cascade
Protein Kinase
An enzyme that catalyzes the transfer of phosphate groups from ATP to another protein