What are the three main types of intercellular interaction?
- Occluding junctions: seal cells tightly together to prevent the passage of any small molecules (ie epithelial cells)
- Anchoring junctions: mechanically attached cells to each other or to the shared ECM using actin or intermediate filaments between cells for attachment
- Communication junctions: gaps between cells which mediate the transfer of chemicals or electrical signals between interacting cells
What are 3 examples of communicating junctions?
Gap junctions; chemical synapses; plasmodesmata (plants only)
What are two types of anchoring junctions?
Desmosones and hemidesmosomes
How do desmosomes and hemidesmosomes relate to junctions?
Both are types of cell-anchoring junctions.
The first holds cells together at adherens junctions using attractive and adhesive transmembrane proteins called adherens
The latter involves focal adhesions, or the binding of cells to the ECM using transmembrane proteins called integrins
What do occluding junctions primarily form?
These junctions primarily form selective permeability barriers between cells and their surrounds, so that molecules can be transferred against their concentration gradients
Describe the structure of a tight, or occluding, cell junction.
This type of cell junction is composed of a row of opposing transmembrane adhesion proteins called claudins and occludins
What is the role of claudin transmembrane proteins in occluding, or tight, junctions?
Specific claudins allow the passage of specific solutes through the tight, or occluding, cellular junctions; claudins facilitate the selectivity/specificity of molecular passage through tight cellular junctions
What are the 3 main components of the cytoskeleton?
- Actin
- Microtubules
- Filaments
Define the cytoskeleton.
An interconnected system of bundled fibers, slender threads, and lattices that extend from the nucleus to plasma membrane
What are the monomer units of microfilaments?
Actin monomers are subunits of…
What are the monomer units of intermediate filaments?
Fibrous subunits are monomers of…
What are the monomer units of microtubules?
Tubulin dimers are monomers of…
From which structure do microtubules grow?
The centrisome!
True or false: Microtubules can be modified post-translation
True; microtubules can be modified post-translation by tyrosination, acetylation, phosphorylation, polyglutamylation or polygycyation
