The plant cell has a cell wall, chloroplasts, plastids, and a central vacuole. None of these structures are found in animal cells.


A plant cell.

In all cells, the cell membrane separates the cells from their environment. All cells are filled is cytoplasm, which contains many different organelles.

The cell membrane has a structure that consists of two layers. The cell membrane protects the cell from foreign substances, bacteria and viruses. It is selectively permeable, which means that it regulates which substances can enter the cell and which are removed from the cell.

Small water molecules are able to permeate the porous cell membrane. Larger molecules, such as glucose, require a specific transport protein to facilitate their movement through the cell membrane. The outer surface of the cell membrane has sensors that allow the cell to take in or block substances from entering.

Cytoplasm contains membrane-bound organelles and the endoplasmic reticulum, which is a system of flat cavities or cisterns that produces and transports substances.

Mitochondria are essential organelles. They break down glucose to release the energy stored in it during a process called cell respiration. Cells also contain various other organelles, such as lysosomes, which digest worn out organelles and food particles, as well as viruses or bacteria.

The genes found in the chromosomes control the function of the whole cell. In plant, animal and fungal cells, the chromosomes are located inside a nucleus. Cells with a nucleus are called eukaryotic cells.

Bacteria do not have a nucleus. Instead, bacteria carry their only chromosomes in their cytoplasm. This means that bacteria are prokaryotic organisms.


An animal cell.