Plant Cell Wall Flashcards
(15 cards)
What are the two main parts of a plant cell?
Cell Wall + Protoplast (Protoplast includes the plasma membrane and everything inside).
What is the main component of the cell wall, and how is it structured?
Cellulose, made of long chains of glucose molecules, forms microfibrils that provide strength.
What are the differences between the primary and secondary cell walls?
Primary Cell Wall: First layer, flexible for growth.
Secondary Cell Wall: Added later, thicker & stronger, contains lignin for rigidity.
What are the two phases of cell wall formation?
Matrix Phase: Includes pectin & hemicellulose.
Cellulose Microfibrils: Provide structural support.
What do pectin and hemicellulose do in the cell wall?
Pectin: Binds water, forms a gel-like structure.
Hemicellulose: Connects microfibrils with side branches for strength
What is extensin, and what does it do?
Extensin is a protein that strengthens the cell wall and controls cell expansion
Where are the cell wall components made?
Polysaccharides (pectin & hemicellulose) → Golgi apparatus.
Extensin (protein) → Rough ER, transported via Golgi.
Cellulose → Synthesized at the plasma membrane by rosette complexes.
How does the cytoskeleton help build the cell wall?
Microtubules guide cellulose synthase rosettes, directing microfibril synthesis.
How does the cell wall control cell shape?
Random microfibrils → Cell expands in all directions.
Aligned microfibrils → Cell expands longitudinally.
What is turgor pressure, and why is it important?
Turgor pressure is when the protoplast pushes against the cell wall, keeping the plant upright.
What happens when a plant loses water?
Wilting: The protoplast shrinks, and the plant loses structure.
Plasmolysis: The plasma membrane pulls away from the cell wall due to extreme water loss.
What is the role of the vacuole in water balance?
Stores water & solutes.
Helps maintain turgor pressure.
Uses osmosis to take in water.
What is lignin, and why is it important?
Lignin is a rigid, waterproofing substance found in the secondary cell wall for extra support.
What is the desmotubule, and what does it do?
The desmotubule is a structure within plasmodesmata that prevents large organelles from passing between cells.
What is plasmodesmata, and what is its function?
Plasmodesmata are small channels that connect plant cells for communication and transport.
