Cell Structure: A Summary

Cells are basic structural & functional units of all living organisms.
For cells to function effectively, they must be able to:

1. Carry out metabolic reactions essential to life (Mainly in cytoplasm)
---> In the cytoplasm are organelles which are structures surrounded by membranes. These "compartments" carry out specific reactions/ functions, eg. Mitochondria and chloroplasts contain enzymes for respiration and photosynthesis respectively, while vacuoles may transport waste material out of the animal cell, and help to keep the cells firm in plant cells.


2. Have genetic material that will control those reactions, plus provide a template to make new cells that are identical (Stored in chromatin in nucleus).


3. Have a partially permeable boundary surrounding the entire cell, which allows the cell to control its internal environment and maintain concentration of solutes and its water potential and pH, as this will affect the chemical reactions going on inside the cell (Cell surface membrane).

Collectively, the cell is made up of protoplasm (living matter), consisting of the cell surface membrane, the nucleus and the cytoplasm.

Plant cells have specialised structures not found in animal cells:

1. Chloroplasts: Used to trap light energy and carry out the process of photosynthesis.


2. A large central vacuole: (Animal cells have numerous small vacuoles.) This vacuole is surrounded by a membrane known as a tonoplast, and is filled with cell sap. These large central vacuoles are seen in most mature (older) plant cells. 


3. Cell wall: Helps the cell to keep its shape, and plays a role in enabling cells to be turgid. One main component is cellulose, which gives the cell wall its strength. Its fully permeable and non-living.


4. Middle lamella: Cementing material found between plant cells. Fully permeable and non-living.