AS Biology - Cell Structure - Organelle functions

Cell Surface (plasma) membrane: 
Definition: The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells. It's made mainly of lipids and proteins. Folds in the cell membrane. 
Function: Regulates the movement of substances into and out of the cell. It also has receptor molecules on it which allows it to respond to chemicals like hormones.

Microvilli:  
Definition: Folds in the cell membrane.
Function: Found in cells involved in processes like absorption such as epithellal cells in the small intestine. They increase the surface area of the cell membrane.

Nucleus:
Definition: Surrounded by a nucleur envelope (double membrane) which contains many pores. The nucleus contains chromatin and often a structure called the nucleolus. 
Function: Chromatin is made from proteins and DNA (DNA controls the cells activities). The pores allow substances to move between the nucleus and the cytoplasm. The nucleus makes ribosomes.

Lysosome:
Definition: Round organelle surrounded by a membrane, with no clear internal structure.
Function: Contains digestive enzymes. These are kept separate from the cytoplasm by the surrounding membrane and can be used to digest invading cells or to break down worn out components of the cell.

Ribosome:
Definition: Very small organelle that floats free in the cytoplasm and is attached to the rough endoplasmic reticulum 
Function: The site where proteins are made.

Endoplasmic Reticulum:
Definition: Two types of endoplasmic reticulum: (1) The smooth endoplasmic reticulum is a system of membranes enclosing a fluid-filled space.
(2)The rough endoplasmic reticulum…