What is Cell Wall of Plant Cell:
The outermost boundary in the plant cell is cell wall. It is secreted by the protoplasm of the cell but itself cell wall is not a living structure. Its thickness varies in different cells of the plant.
Structure and chemical composition of plant cell:
It is composed of three main layers:
- Middle Lamella
- Primary Wall
- Secondary Wall
- Middle Lamella: The middle lamella is first to be formed in between the primary walls of the neighboring cells and binds them together. It is mainly composed of magnesium pectate. (So, it is not true cell wall).
- The Primary Wall: The primary wall is composed of cellulose and some deposition of pectin and lignin. Cellulose molecules are arranged in a criss-cross arrangement. The primary wall is a true wall and develops in newly growing cells.
- The Secondary Wall: The secondary wall is formed on its inner surface and is comparatively thick and rigid. Chemically it is composed of inorganic salts, silica, waxes, cutin, etc. (In addition to cellulose and lignin).
Functions of Cell Wall:
- Shape & Rigidity: Plant Cell wall provides a definite shape to the cell and keeps it rigid.
- Permeable: It does not act as a barrier to the materials passing through it.
- Support & Strength: Plant cell wall provides mechanical strength and skeletal support for the individual cell and to the plant as a whole.
- Movement of water & minerals: Water and minerals can move through an interconnected system of cell wall (i.e. the apoplast).
- Protection: Plant cell wall protects the cells from osmotic lysis.
What is the difference between Cell Membrane and Cell Wall:
- Cell membrance is found in all the living organisms i.e. plant and animals.
- Cell membrane is the outermost boundary of animal cell.
- Cell membrane is a living structure.
- Cell membrane is differentially (selectively) permeable membrane and controls transport of material across it.
- Cell membrane is mainly composed of protein and lipids.
- Cell membrane is thin, elastic, delicate and self repairable to some extent.
- Loss of plasma membrane or cell membrane causes death of cell.
- Cell membrane is composed of lipid bilayer and differently arranged protein molecules.
- The cell wall is found only in plant cells.
- The cell wall is the outermost boundary in plant cell.
- The cell wall is a nonliving structure though it is secreted by protoplasm.
- The cell wall is permeable to all dissolved substances. It does not act as a barrier.
- Plant’s cell wall is composed of cellulose while the cell wall of fungi is composed of chitin and the cell wall of prokaryotes is composed of murein.
- The plant’s cell wall is tough and rigid in structure.
- Removal cell walls may not cause the death of cells.
- Plant’s cell wall composed of cellulose fibril layers showing a criss-cross arrangement. This composition is different in prokaryotes and fungal cells.
Difference Between Plant and Animal Cells:
Plant Cell Diagram:
Animal Cell, Cell Wall:
Animal cell does not possess cell wall.
Cell membrane is the outermost boundry.
Plant’s Cell, Cell Wall:
Plant cell is surrounded by a rigid cell wall made up of cellulose.
Cell wall is the outermost boundary.
Animal Cell, Chloroplast:
No animal cell contains chloroplast or chlorophyll.
Plant’s Cell, Chloroplast:
Most of the plant cells contain chloroplast and chlorophyll. Hence, they are autotrophy.
Animal Cell, Position of Nucleus:
Animal cell possesses several small vacuoles and nucleus is central in position.
Plant Cell, Position of Nucleus:
A mature plant cell has a single large, central vacuole and nucleus lies in the peripheral cytoplasm.
Animal Cell, Centrioles & Mitotic Apparatus:
Animal cells have centrioles and their mitotic apparatus consists of spindle fibers, centrioles, and asters.
Plant Cell, Centrioles & Mitotic Apparatus:
Higher plant cells lack centrioles and their mitotic apparatus consists of only spindle fibres.
Animal Cell, Cytokinesis:
Cytokinesis (division of cytoplasm) in a dividing animal cell takes place by constriction or pinching of the cell membrane and cytoplasm in the equatorial area.
Plant’s Cell, Cytokinesis:
Cell plate formation of phragmoplast appears during the division of a plant cell for the cytokinesis.