MadSci Network: Botany

Re: Are cellulose cell wall presents in all parts of the plant ?

Date: Thu Jun 29 09:41:30 2006
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1150418693.Bt

Yes, cellulose cell walls are present in all cells in leaves, fruits, roots and
flowers. At maturity, some cells are dead and consist mainly of the cell wall.
The dead cells lack a cell membrane and cytoplasm. 

Cells walls are considered completely permeable to mineral nutrients, unlike
cell membranes which selectively absorb mineral nutrients. Mineral nutrients can
flow into and through cell walls by diffusion but also often move by mass flow.
For example, in roots, water moves across root cell membranes freely and carries
dissolved mineral nutrients with it. As the water passes across a cell membrane,
it may leave behind some of the mineral nutrients, and they can accumulate in
the cell walls.

The nonliving part of the plant, mainly the cell walls and intercellular spaces
is termed the apoplast. That is in contrast to the symplast, which is the living
part within the cell membranes. Diffusion and mass flow operate freely in the
apoplast or apoplastic pathway. Water and mineral nutrients can move freely into
the roots in the apoplast until the Casparian strip, at which point water and
mineral nutrients must cross a membrane to continue further. Once across the
Casparian strip, they can exit the symplast into the apoplast again.


Transport of Water and Minerals in Plants

Diagram of root cross section and endodermis

Diagram of apoplastic and symplastic pathways in the root

Current Queue | Current Queue for Botany | Botany archives

Try the links in the MadSci Library for more information on Botany.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2006. All rights reserved.