Cell Structure & Diversity 3- Cell Walls & Respiration Flashcards
What is a plant cell composed of?
Cell wall and protoplast
What is the protoplast?
Cell membrane and everything found inside it
What structures are unique to plant cells?
Cell wall, plasmodesmata, chloroplasts and central vacuole
What is the main component of the cell wall?
Cellulose
What is the structure of cellulose?
A glucose polymer that is highly ordered and forms long ribbon-like structures
How does the structure of cellulose help the cell wall?
The highly ordered structure of cellulose makes it very strong and when multiple cellulose ribbons cross link to from microfibrils it makes a strong and inert structure.
What is the first phase of the cell wall and what is involved?
Crystalline Microfibullar Phase which involves cellulose
What is the second phase of the cell wall and what is involved?
Noncrystalline Matrix which involves pectin and hemicellulose polysaccharides as well as a network extension protein
What is hemicellulose?
A heterogenous group of polysaccharides. A long chain of one type of sugar and a short side chain forms a rigid structure.
What is pectin?
Branched negatively charged polysaccharides which bind water and have gel-like properties.
What is the function of extensin?
Extension cross linking of pectin and cellulose dehydrates the cell wall, reduces extensibility and increases strength.
What is controlled by extension cross linking?
Expanding of cells
Where is the cell wall made?
Outside of the cell
What organelles are needed to make the cell wall?
Golgi complex and rough ER
What are the organelles needed for in making the cell wall?
Coordinating synthesis and delivery of cellulose microfibrils, polysaccharides (pectin and hemicellulose) and cell wall proteins (extensins)
Where are cellulose microfibrils made and what by?
At the plasma membrane by rosettes
Where are the polysaccharides made?
At the Golgi complex and then transported to the cell wall using vesicles
What makes extensions?
Rough ER
How are materials for the cell wall transported?
In vesicles by constitutive exocytosis and the vesicles then fuse to the plasma membrane and release the contents outside
What are rosettes attached to?
Cortical Microtubules
How do rosettes make microfibrils?
Move along the microtubules and joins glucose molecules together to make the cellulose microfibril
What is affected by the way the microtubules are laid?
Where the cellulose is formed and therefore the cell shape
What is the middle lamella?
The sticky portion between the cells which sticks them together
What are the functions of the cell wall?
Regulating the shape, providing structural support and preventing excessive water uptake