Plant Cell

Cell Organelle

1. Cell Membrane
2. Cytoplasm
3. Nucleus
4. Ribosomes
5. Mitochondria
6. Cell Wall
7. Chloroplasts
8. Large Vacuole

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1. Cell Membrane

Function:

• Retains the cell contents.

• Controls what enters and leaves the cell.

• It is selectively permeable. Composition:

• Made up of a thin layer of lipids and proteins.

• Two layers of phospholipid molecules form a lipid bilayer.

Cell Membrane

2. Cytoplasm

Function:

• A jelly like substance that suspends cell organelle

• Chemical reactions occur here. Composition:

• Includes sugars, which are needed for diffusion and osmosis to occur.

3. Nucleus

Function:

• The control centre of the cell.
• Responsible for DNA replication and cell division.

Composition:

• Surrounded by a double membrane with nuclear pores.
• Contains DNA which is organised into chromosomes.

4. Ribosomes

Function:

• Protein synthesis (make protein). Composition:

• Made of protein and RNA (ribonucleic acid).

5. Mitochondria

Function:

• Aerobic respiration occurs here. Composition:

• A double membrane with inner folding of cristae.

• These increase surface area, allowing more energy-producing reactions to occur.

• For example, mitochondria in the legs are heavily folded, as they require lots of energy.

• The number of mitochondria in a cell depends on its energy needs.

• Cells requiring more energy (like leg muscles) have more mitochondria.

• Mitochondria contain their own DNA.

  

6. Cell Wall

Function:

• Provide strength and support to plant cells. Composition:

• Made of cellulose (a structural polysaccharide).

• Fully permeable.

7. Chloroplasts

Function:

• Photosynthesis.

Composition:

• Contain the green pigment chlorophyll, which allows plants to photosynthesise.
• They have their own DNA, allowing them to replicate and produce new chloroplasts.

8. Large Vacuole

Function:

• Store water, food and waste.

• Helps to maintain the shape of the plant cell (turgid). Composition:

• A large fluid filled sac.

• Filled with cell sap (a mixture of water, minerals and pigments).

• A plant cell is turgid when it is full of water. This causes the cell membrane to press against the cell wall and makes the cell firm.
• A plant cell is plasmolysed when it loses water. This causes the cell membrane to pull away from the cell wall. The cell becomes less firm and the plant wilts.

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