topic 7 Flashcards
signal transduction pathways used for
converting extracellular signals into cellular responses
two types of cell communication
local signaling and long-distance signaling
what are the ways cells can communicate through local signaling (3)?
- direct contact
- cell-cell recognition
- local regulators
what type(s) of local signaling do we see in both animal & plant cells?
direct contact
what type(s) of local signaling do we see in only animal cells?
cell-cell recognition and local regulators
what are cell junctions responsible for in direct contact signaling?
to allow molecules to pass readily between two adjacent cells without crossing the plasma membrane
what is cell-cell recognition?
when animal cells communicate & recognize each other via direct contact using surface molecules (ex: carbohydrates)
what are local regulators?
messenger molecules that travel only short distances (ex: neurotransmitters/growth factors)
what two types of signaling use local regulators?
paracrine and synaptic signaling
what is paracrine signaling?
a secreting cell acts on nearby target cells by discharging molecules of a local regulator (ex: growth factor) into the extracellular fluid
what is synaptic signaling?
a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell
what are the types of cell junctions?
- communicating junctions
- occluding junctions
- anchoring junctions
what are the type(s) of communicating junctions?
- gap junctions
- plasmodesmata
what is the function of gap junctions?
allow molecule and ion exchange between animal cells
where are gap junctions located?
along the apical surfaces of cells of various tissues (ex: epithelial)
what are connexins?
membrane proteins that form gap junction channels
where does the transport of Ca+2 between neighboring smooth muscle cells takes place?
Gap junctions
what is the function of plasmodesmata?
allow molecule exchange in plant cells (ex: water)
what are the type(s) of occluding junctions?
tight junctions
what is the function of tight junctions?
- inhibit cell-to-cell communication (molecule exchange)
- create an exclusion zone around cells to prevent leakage of ECF from a layer of epithelial cells
tight junctions connect to ____
actin microfilaments
where are tight junctions located?
underneath the apical surface of epithelial cells
the 2 transmembrane proteins are tight junctions made from?
- claudin
- occludin (linked to actin microfilaments)
type(s) of anchoring junctions (cell-cell)
- desmosomes
- adherens junctions
type(s) of anchoring junctions (cell-ECM)
- focal adhesion
- hemisdesmosomes
actin filaments are present in
adherens junctions / focal adhesions
intermediate filaments are present in
desmosomes/hemidesmosomes
the function of desmosomes
anchor to the cytoplasm through intermediate filaments (ex: keratin)
