What are the main types of cell-cell junctions in animal tissues, and what are their key structural proteins and functions?
The main types are adherens junctions (use cadherins linked to actin filaments to anchor cells), desmosomes (use cadherins linked to intermediate filaments to bind epithelial cells), tight junctions (use claudins or occludins to form seals preventing leakage), and gap junctions (use connexins to allow communication between cells).
How do tight junctions contribute to the polarity of epithelial cells?
Tight junctions form seals between cells that prevent the mixing of proteins and lipids between the apical and basal surfaces, helping maintain distinct cellular regions and thus cell polarity.
What is the primary function of gap junctions, and which proteins are involved in their structure?
Gap junctions allow direct communication between adjacent cells by permitting the passage of water and small inorganic ions; they are formed by connexin proteins.
How do desmosomes differ from adherens junctions in terms of their cytoskeletal connections?
Desmosomes connect to intermediate filaments inside the cell, while adherens junctions connect to actin filaments.
What is the equivalent of gap junctions in plant cells, and what is their function?
Plasmodesmata are the plant cell equivalent of gap junctions; they connect the cytosols of adjacent plant cells, allowing communication and transport of molecules.
What are the main types of cell-cell junctions in animal tissues and their key structural proteins?
Adherens junctions (cadherins and actin filaments), desmosomes (cadherins and intermediate filaments), tight junctions (claudins or occludins), and gap junctions (connexins) are the main types.
How do tight junctions help maintain the polarity of epithelial cells?
Tight junctions form seals that prevent the mixing of proteins and lipids between the apical and basal surfaces, maintaining distinct cellular regions and cell polarity.
What is the primary function of gap junctions and which proteins form them?
Gap junctions allow direct communication between adjacent cells by permitting the passage of water and small inorganic ions; they are formed by connexin proteins.
How do desmosomes differ from adherens junctions in terms of their cytoskeletal connections?
Desmosomes connect to intermediate filaments inside the cell, while adherens junctions connect to actin filaments.
What is the plant cell equivalent of gap junctions and what is their function?
Plasmodesmata are the plant cell equivalent of gap junctions; they connect the cytosols of adjacent plant cells, allowing communication and transport of molecules.