Bio - Chapter 7 - Cell to Cell Interactions
Terms
undefined, object
copy deck
- receptor proteins
-
-have a 3-dimensional shape that fits a specific signal molecule.
-when a signal molecule and a receptor protein bind, a change in the receptor protein is induced and a response is generated. - techniques for finding receptor proteins
-
1) immunochemistry
2) molecular genetics - types of cell signaling
-
1) direct contact
2) paracrine signaling
3) endocrine signaling
4) synaptic signaling
-autocrine signaling - autocrine signaling
- when cells send signals to themselves, secreting signals that bind to specific receptors on their own plasma membranes.
- direct contact
- cell to cell is in close contact
- paracrine signaling
- signal molecules are released by a cell that diffuse through the extracellular fluid to other cells, but it short lived and localized.
- endocrine signaling
- signal molecules released by cells remain in extracellular fluid for a long time and travel wideley throughout body.
- hormones
- longer lived signal molecules used in endocrine signaling
- synaptic signaling
- intracellular communication that provides rapid communication using neurtransmitters, which move through a synaptic gap rather than through intracellular fluid.
- neurotransmitters
- signal molecules used in synaptic signaling
- chemical synapse
- association of a neuron and its target cell
- intracellular receptors
-
receptors located within the cell and trigger a variety of activity
- ex:
act as gene regulators
act as enzymes - cell surface receptors
-
receptor proteins on the outer surface of the cell that convert the extracellular signal to an intracellular one.
-useful for water soluble signals that cannot diffuse through plasma membranes. - Types of cell surface receptors
-
1) Chemically Gated Ion Channels
2) Enzymic Receptors
3) G Protein Linked Receptors - chemically gated ion channels
- open or close when signal molecules bind to the channel
- enzyme receptors
- usually activate intracellular proteins by phosphorylation
- ion channel
- pore in chemically gated ions channels which ions pass through
- protein kinases
- enzyme activated when a signal molecule binds to an enzyme receptor, it adds prosphate groups to proteins
- G protein linked receptors
- acts indirectly on enzymes or ion channels in the plasma membranes with the aid of an assisting protein, G protein (aka GTP)
- G protein
- assisting protein in G protein linked receptors
- second messengers
-
relay messages from receptors to target proteins.
ex:
cAMP (found in all animal cells)
calcium ions (high outside cell and in ER, low in cytoplasm. - adenylyl cyclase
- stimulated by G protein, produces large amounts of cAMP within the cell
- tissues
- highly specialized groups of cells (blood, muscle)
- cell identity
- cells contain an array of marker proteins located on the cell surface
- tissue specific identity markers
-
glycolipids (tissue specific cell surface markers)
MHC proteins (self from nonself) - cell junctions
- long lasting or permanent connections inbetween cells
- types of cell junctions:
-
tight junctions
anchoring junctions
communication junctions - tight junctions
- connect plasma membranes of adjacent cells in a sheet, preventing small molecules from leaking inbetween the cells
- anchoring junctions
- mechanically attach the cytoskeleton of a cell to the cytoskeletons of other cells or the extracellular matrix
- desmosomes
- anchoring junctions that connect the cytoskeletons of adjacent cells using cadherins (critical link)
- adherens junctions
- anchoring junctions that connect the actin filaments of one cell with those of neighboring cells or with extracellular matrix (critical link in this is integrin)
- communicating junctions
- chemical or electrical signal passes directly from one cell to an adjacent cell
- gap junctions
- communicating junctions in animal cells
- plasmodesmata
-
communicating junctions in plant cells
-contain central tubule that connects the ER of the two cells