11/03 Lecture 8 - Cell Walls in Plants

Central vacuole

This is a large, membraned organelle that developed from the coalescence of multiple smaller similar organelles, and which contains cell sap

Cell sap

This is a solution that contains water, and the cell’s main repository of inorganic ions

Cell wall

This is an extracellular matrix from plant cells that protects the protoplast, maintains its shape, and allows plant tissue to withstand the force of gravity

Middle lamella

This is a thin layer between outer layers of adjoining cell walls rich in pectin that sticks the cell walls to each other

Plasmodesmata

This describes small channels between the cytoplasm of plant cells that connect them an allow for the passage of cytoplasmic fluid and contents

Microfibrils

This describes bundles of cellulose chains bound together like a rope that partly compose the cell wall

Hemicellulose

This is a substance made from a heterogenous chain of glucose monomers with short side chains

Extensin

This is a protein, synthesised via the endomembrane system, that can block the expansion of cells

Cytoplasmic streaming

This is the movement of chloroplasts and other motile organelles around the cell via microfilaments in the cytoskeleton

Cellulose synthase rosette

This is a protein inside the plasma membrane that synthesises cellulose for use in producing the cell wall

Protoplast

This describes every part of the plant cell excluding the cell wall

Turgor pressure

This is the pressure exerted by the protoplast pushing against the cell wall

Plasmolysed

This describes the state of a plant cell having too little water and shrivelling up

Lignin

This is an organic macromolecule that fills the space between cellulose and polysaccharides, adding strength, watertightness, and rigidity to a secondary cell wall