Biology 2.9

Special structures in plant cells and their role

Structure and function of chloroplasts

Distinct structures in plant cells give them their unique shape.

Plant cells have a rigid exterior to allow for upright growth.

Photosynthesis: Plants make their own food.

Plant cells have unique structures not found in animal cells:

• Cell Wall

• Large Central Vacuole

• Plastids (like Chloroplasts)

Function: Provides structural support and protection.

Structure: Made of cellulose and proteins.

Prevents bursting: Controls water flow into the cell.

Takes up 30-90% of the plant cell’s volume.

Function: Maintains turgor pressure, stores pigments, and helps in defense.

Stores: Water, enzymes, ions, salts, and other substances.

Different types of plastids:

• Chloroplasts: Photosynthesis (makes food).

• Chromoplasts: Store pigments (color of flowers/fruits).

• Leucoplasts: Storage of starch and synthesis of molecules.

Function: Capture sunlight and convert it into food through photosynthesis.

Structure:

• Enclosed by an inner and outer membrane.

• Contains stacks of thylakoids arranged into grana.

• Stroma: The fluid inside, contains DNA and ribosomes.

Plant cells have unique structures like the cell wall, central vacuole, and plastids.

Cell wall provides support and protection.

Central vacuole helps with storage and maintaining cell pressure.

Chloroplasts perform photosynthesis, converting sunlight into food for the plant.