Extra cellular components Collagen microfibrils 2016 Paul Billiet

The extracellular matrix Plant cell secrete cellulose and other carbohydrates n Fungi and insect cells secrete chitin n Bacteria secrete murin n Animal cells secrete proteins (e. g. collagen) glycoproteins and other conjugated proteins n © 2016 Paul Billiet ODWS

Functions of extracellular matrix Mechanical, they give tissues strength and elasticity n Protection against extracellular change and retention of water n Control of cell behaviour by binding of growth factors and interaction with cellsurface receptors n © 2016 Paul Billiet ODWS

Animal tissues Image Credit; www. steve. gb. com

THE PLANT CELL WALL The formation of a cell plate starts as soon as

Cell plate to cell wall The cell plate becomes the middle lamella that glues the cells together © 2016 Paul Billiet ODWS New cell wall material is secreted either side of the middles lamella = primary cell wall (no cellulose)

Growth of the cell is orientated by the appearance of cellulose microfibrils Plasmodesmata Sap vacuole © 2016 Paul Billiet ODWS The secondary cell wall consists of cellulose microfibrils secreted inside the primary cell wall When this forms the cell stops growing and takes its final form