WEEK 11 - CELL JUNCTIONS

Question 1

Social cells

Answer 1

• Cells do not exist in isolation; the interact physically and chemically with one another
• Transmembranous glycoprotein receptors at the cell surface “read” chemical signals within the body
• Most cells are physically attached to their surroundings:
• Specialised cell junctions occur at points of cell-cell & cell-matrix contact in all tissues: particularly plentiful in epithelia
• Visualised using freeze fracture electron microscopy: reveals interacting plasma membranes (& often underlying cytoplasm & the intervening intercellular space) are highly specialised in these region

Question 2

Cell junctions

Answer 2

classified into three functional groups :

• Occluding or tight junctions:seal epithelial cells together tightly to prevent even small molecules from leaking from one side to the other
• Anchoring junctions:mechanically attach cells to their neighbours or to the extracellular matrix
• Communicating junctions:mediate the passage of small molecules from one cell to the next