cell wall AS level

1. Cell Wall
These are found in plant cells only
Cell walls provide mechanical support
and protection

2. Because the wall prevents the cell from
bursting this allows turgor pressure to
give the plant support

3. The wall is made from cellulose and other
polysaccharides
Fungi and Prokaryotes have cell walls
made of other substances

5. The cell wall is made in Golgi apparatus
Golgi vesicles move to the cell plate (at
the equator of a dividing cell) at the
end of nuclear division
Golgi vesicles
containing
Calcium
pectate
Forming cell
plate with
middle
lamella being
formed
Note the vesicle membrane
surrounds the new wall

6. The vesicles fuse to form the middle
lamella
This contains Calcium Pectate which
holds the neighbouring cell walls
together
The membranes from the vesicles fuse to
form the cell surface membrane

7. • The primary cell wall is made next
• This is made of cellulose molecules
that are bundled together to form
microfibrils

8. The bundles are held by Hydrogen-bonds
These are in turn bundles to form
cellulose fibres
Hemicellulose and pectins hold fibres
together
Cellulose has a high tensile strength

10. The primary cell wall laid down in different
directions
There are gaps in the wall called plasmodesmata
through which cytoplasmic connections are
made between cells
The Secondary wall is only laid down once the
cell has stopped growing

11. The cellulose fibres are laid in different directions
which increases the strength
They may have lignin or suberin added
The cellulose cell wall is freely permeable.
Water and ions move through the spaces between
the cellulose fibres. This is called the apoplast