lecture 7 - plant cell wall Flashcards
What does the plant cell wall enclose?
The protoplast.
What is the major component of the plant cell wall?
Cellulose
What is the structure of cellulose?
Chains of glucose (a polymer), forming ribbons
What are cellulose micro fibrils?
Layers of cellulose ribbons bonded together into strong chains
What are the 2 phases of the cell wall?
Crystalline microfibrillar phase and Non-crystalline matrix
What is the chemical component of the Cell Wall Phase 1?
Cellulose molecules (which form cellulose/fibre microfibrils)
What are the three components of Phase 2 of the plant cell wall?
Pectin and hemicellulose polysaccharides, extensin (a protein)
What is the structure of hemicellulose?
Long chains of 1 type of sugar, with oligosaccharide side chains.
What are the properties of hemicellulose?
Rigid structure, but not as strong as cellulose.
What is the structure and properties of pectin?
Branched negatively charged polysaccharides, which bind water, giving it gel-like properties.
What element of plant cell structure does extensin determine?
Extensibility (expansion)
How does extensin limit extensibility?
When extension fibres partake in cross-linking, the cell wall become dehydrated, and the cell cannot expand as the wall becomes more rigid.
Where are cellulose microfibrils synthesised?
At rosettes on the cell membrane
Where are cell wall polysaccharides synthesised?
Pectin and hemicellulose are made in the golgi, and transported via vesicles.
Where are cell wall proteins (extensin) synthesised?
In the Rough Endoplasmic Reticulum, then transported by vesicles to the cell wall.