Plant Cell Walls Chapter 3

Where is the cell wall of plant cells located? A.Inside the plasma membrane B.Outside the plasma membrane C.Between the plasma membranes of two adjacent cells

The Eukaryotic Plant Cell cell wall plasma membrane cytoplasm various organelles cytoplasmic streaming nucleus vacuole bound by tonoplast

Cell Wall Functions constrains protoplast expansion gives turgidity to plant determines size/shape of cell cells classified largely based upon cell wall traits contain enzymes, absorb, transport and secrete substances play important role in defense NOT JUST A CONTAINER BOUNDARY

Primary Cell Walls outside of the plasma membrane deposited while cell grows contain thin areas primary pit fields plasmodesmata connect cell-to- cell (cytoplasmic connections) shared with adjacent cell middle lamella joins primary cell walls of adjacent cells

Plasmodesmata

Chemistry of Primary Cell Walls cellulose glucose monomers bundled into microfibrils wound and coiled into macrofibrils hemicelluloses polysaccharides that limit cell wall extensibility pectins primary cell walls and middle lamella give wall pliability; act as cement glycoproteins lignins cutin suberin waxes

Cell growth determined by cellulose microfibril orientation

Secondary Cell Walls formed inside the primary wall different staining qualities than primary cell wall very thick not present in all cells formed after cell growth function in strength and water transport abundant cellulose and hemicellulose pectins and glycoproteins absent - thus not elastic lignins common - gives hardness and rigidity

Basswood stem (angiosperm stem) dicot stem Secondary Cell Wall Examples Vascular Tissue xylem vessel elements tracheids (gymnosperms) schlerenchyma fibers phloem schlerenchyma fibers Ground Tissue schlerenchyma fibers monocot stem Pine stem dicot stem

The primary cell wall of plant cells is located inside the plasma membrane. True False

The secondary cell wall is located inside the plasma membrane. True False

Plant body organization Plant body Systems Shoot & root systems Organs Vegetative: root, stem, leaf Reproductive: flower, fruit Tissue Systems Dermal, ground, vascular Tissues Cells

Meristem classification: apical root tip & shoot tip produce primary growth lateral to the side of stems and roots produce secondary growth intercalary between mature tissues help regenerate parts that are removed (grass leaves and herbivory) primary (formed first) produce primary tissue systems three types protoderm ground meristem procambium secondary (formed after 1°) produce secondary tissue systems two types vascular cambium cork cambium LOCATIONFUNCTION

1° Tissue Systems Dermal tissue system covers and protects plant surface epidermis Ground tissue system parenchyma, collenchyma and sclerenchyma cells mesophyll of leaves young green stems (pith and cortex) Vascular tissue system conducts water and solutes (xylem) conducts sugars (phloem) leaf stem root

Plant body organization Tissues with cell types Simple Parenchyma Chlorenchyma Sclerenchyma Collenchyma Complex Epidermis Ground cells Guard cells Xylem Vessel elements parenchyma Phloem Sieve tube elements Companion cells Sclerenchyma fiber

parenchyma collenchyma

sclerenchyma fibers

vessel elements sclerenchyma fibers tracheid

Primary Meristems Forms primary tissue Elongates root and shoot types protoderm epidermis procambium primary xylem and phloem ground meristem pith and cortex of stems and root, mesophyll of leaves ground meristem procambium protoderm

Secondary Meristems Forms secondary tissue Growth in lateral direction leads to increase in girth or circumference wood in trees 2 types vascular cambium secondary xylem secondary phloem cork cambium periderm 2  xylem 2  phloem vascular cambium periderm