All cells have a cell surface membrane; these are made up of phospholipids and make up a bilayer. A phospholipid has a hydrophilic head and a hydrophobic tail which is made up of 2 fatty acid chains; these are arranged is two layers with the tails facing inwards. Lipids soluble material can move through the plasma membrane but water soluble substance are unable to pass and therefore protein ion channels are required to monitor the inward and outward movement of these substances. This bilayer that surrounds the cell can be described as a fluid mosaic model, fluid because the molecules are still able to move allowing the cell to have a flexible shape and mosaic because the proteins embedded in the membrane are all different sizes shapes and pattern.
The nucleus is the most prominent feature if a eukaryotic cell, it controls the cell’s activities and contains the organisms hereditary material. The nucleus is made up of a number of parts; the nuclear envelope is a double membrane that continues with the endoplasmic reticulum, it controls the entry and exit of materials and it contains the reactions taking place within it. The nuclear pores are passages in the envelope and allow molecules such as mRNA to move out of the nucleus, so that it can be spliced and the introns removed and then translated to form a protein. The nucleoplasm makes up most of the nucleus as it is a jelly like, granular material. Within this chromatin is found, this is the DNA found in the nucleoplasm that chromosomes take up when the cell is not dividing. The nucleolus is a small spherical body within the nucleoplasm that manufactures