BIO130H1 Chapter : pg.1158-1163.docx

• School: UTSG
• Department: Biology
• Course: BIO130H1
• Professor: John Coleman

Document Summary

Passageways from cell to cell: gap junctions and plasmodesmata. Gap junctions couple cells both electrically and metabolically. Gap junction have two distinct families connexins and innexins. Channels allow inorganic ions and other small water-soluble molecules to pass through. Inorganic ions, sugars, amino acids, nucleotides, vitamins can pass. Macromolecules (proteins, nucleic acids and polysaccharides) cannot pass. This can be determined by inserting red dye on molecules and the pore size is 1. 5nm. A gap-junction connexon is made up of six transmembrane connexin subunits. Gap channels can form homotypic or heterotypic channels. Some gap junctions require a electrical current to function. Cells can regulate the permeability of their gap junctions. Ca2+ can leak into the cell if there is damage: the gap junctions will close. In plants, plasmodesmata perform many of the same functions as gap junctions. Thin structure between the plasmodesmata is called a desmotubule.