B2 1.1 Animal Building Blocks

Each cell is surrounded by a very thin cell membrane that holds the cell together. The cell membrane also controls what goes into anf out of the cell

Cells contain smaller parts called organelles. These include the nucleus, mitochondria and ribosomes.

The single nucleus controls the cell's activities and it is surrounded by a watery cytoplasm.

It contains DNA, the genetic material the provides the instructions for synthesising the chemicals the cell needs, like enzymes. 

Inside the cytoplasm hundreds of chemical reactions take place and these reactions are controlled by the enzymes.

Mitochondria uses glucose in respiration to release energy for the cell.

Ribosomes are the smallest organelles. They build up or synthesise proteins from smaller, simpler compounds called amino acids.

Specialised cells have different shapes and many have special features that are relates to what they do. 

Muscle Cell

Sperm Cell

Nerve Cell

Epithelial Cell

These are all types of specialised cells.

Spindle-shaped muscle cells have fibrils and can shorten in length.

Sperm Cells have a tail to help them more to find the egg.

They also have a high number of mitochondria to release energy for movement.

Nerve cells have long fibres that carry electrical impulses. Brances of cytoplasm at each end of the cell facilitate communication with other nerve cells.

These specialised epithelial cells have tiny hair-like structures, called cilia, on their free surface. They are known as ciliated epithelial cells. The cilia sway constantly back and forth to move particles along.