Plant Cell Structure

Study Notes

Plant Cell Vacuoles & Cell Wall

Eukaryotic cells have a nucleus and membrane-bound organelles, distinguishing them from prokaryotic cells.
Plant cells are a specialized type of eukaryotic cells.
Plant cells have two distinguishing structures: large vacuoles and cell walls.
Vacuoles are membrane-bound organelles found in both plant and animal cells.
Plant vacuoles are larger than animal vacuoles and have various functions like storage, growth, and waste elimination.
Many plant cells have a single large central vacuole, while animal cells have smaller lysosome-type vacuoles involved in waste elimination.
The central vacuole in plant cells can represent up to 90% of the cell's inner space and maintains turgor pressure.
The central vacuole has a tonoplast membrane that regulates water flow and contains cell sap with water, enzymes, ions, and other molecules.
The primary role of the central vacuole is to maintain turgor pressure, shape the cell, and store water, nutrients, and waste.
The cell wall, made of cellulose and other polysaccharides, provides strength and flexibility to plant tissues and works with vacuoles to maintain turgor pressure.
Plant cell walls have three layers: primary cell wall, secondary cell wall, and middle lamella.
The primary cell wall is strong and flexible, and the secondary cell wall is more fibrous and protects against damage.
The middle lamella contains pectin and helps hold plant cells together.
The cell wall's main functions include maintaining cell shape, regulating water content, facilitating communication between cells, protecting against pathogens and insects, and storing energy for growth.
The cell wall and central vacuole work together through osmosis to maintain turgor pressure.
Osmosis causes water to enter the central vacuole, increasing internal water pressure and pushing the cell membrane against the cell wall.
This turgor pressure helps the plant cell maintain its shape.
In a hypotonic environment, the plant cell maintains its shape due to turgor pressure, while in an isotonic environment, the cell becomes soft and flaccid.
In a hypertonic solution, the plant cell loses water and wilts, despite the cell wall maintaining its shape.