April 13th- Extracellular Matrix And Connective Tissues
What does a cell wall do?
stronger and more rigid then extracellular matrix in animal cells -primary cell walls allow growth (all cells have them) -secondary: provide extra strength, provide support and protection (chitinases, protein inhibitors and antibiotics may be present)
what makes up a cell wall?
mostly carbohydrates (cellulose and lignins)
what is a CMF? how is it synthesized?
cellulose microfibrils--provide a tensile strength -a transmembrane cellulose synthase complex (CSC) located in the plasma membrane polymerizes glucose into cellulose, CSC also braids together 40-60 cellulose molecules, moves through plasma membrane and spins out CMF behind it
how to the microfibrils know how to organize?
CSC guided by cortical microtubues lying just below the plasma membrane, possibly the CSC is attached to the microtubule through a motor molecule
how does a plant cell use the cell wall in growth?
in growing cell- CMF parallel to each other and microtubules on the other side, proton pumps pump protons into wall, activates expansin -expansin loosens bonds between CMFs and glycans, softens wall (can expand) turgor pressur makes cell elongate perpendicular to orientation of CMFs cell shape determined by direction of cell expansion
what is the difference between collagen and cellulose?
collagen-fibrous protein in animals to provide tensile strength in extracellular matrix cellulose is in plants and cell walls