Lecture 14 Flashcards
What are the four components of the primary cell wall?
Cellulose 25-30%
Pectin 35% ( lexibility)
Hemicellulose 15-25%
Extensin(protein) 5-10%
What components of the cell wall makes up the crystalline microfibrils?
Cellulose ( a long chain of glucose which from microfibrils)
- creates a rigid & regular structure
Where is cellulose synthesised?
Rosettes of cellulose synthase(enzyme) on cell wall
What components of cell wall make up the non-crystalline matrix?
- Hemicellulose polysaccharides
- Pectin polysaccharides
Where is hemicellulose & pectin synthesised?
Golgi body
Where is extensin synthesised?
roughER
In what ways can cellulose microfibrils be orientated?
- Randomly orientated
- Right angles to the long axis of cell
What components make up the secondary cell wall?
- Cellulose
- Pectin
- LIGIN gives cell wall its strength
What is the middle lamella between adjacent cell walls made up of?
pectin
The second cell walls has 3 layers how are they orientated?
microfibrils are layered randomly which increases the strength in the secondary cell wall
What the main differences btw the primary and secondary cell wall?
Primary is thinner
Secondary has 3 layers
Secondary has more cellulose, less pectin and LIGIN
microfibrils are layered randomly increasing the strength in the secondary cell wall
What is the plasmodesmata?
Are channels in plant cell walls that allow continuity of the plasma membrane form two adjacent cells
What is the function of plasmodesmata?
Allows communication
Movement of substances - cytoplasmic exchange
How do plant viruses use plasmodesmata?
Plant viruses move from cell to cell via the plasmodesmata. Viral DNA is too large to move freely through the channels so viruses thread their RNA through the plasmodesmata
