CELLS

=Cells= [image:http://i.imgur.com/zEOo4wk.png?1] The cell is the structural and functional unit of all known living organisms. It is the smallest unit that is still classified as living, and is the building block of all life. Some organisms, such as most bacteria, are unicellular consisting of a single cell. Other organisms, such as humans, are multicellular (consist of two or more cells). Humans typically consist of around 100 trillion cells. Cells are the smallest living things that can replicate independently. Cells consist of a cytoplasm, a watery fluid that contains many biomolecules and other cell components, that is enclosed within a membrane. There are two basic types of cells prokaryotes and eukaryotes. ==Prokaryote Cells== [image:http://i.imgur.com/Cds3t6N.png?1] Prokaryotes are a group of simple, single celled organisms. They don’t have a nucleus but have a single circular DNA that moves freely within the cell. Due to the lack of the nuclear membrane, the ribosome’s can attach directly to the mRNA when it is still being transcribed. Unlike eukaryotes, some prokaryotes have plasmids, small circular DNA, which can replicate independently of the main chromosome and are a useful tool in genetic engineering. Prokaryotes lack most of the other organelles found in eukaryotes. Prokaryotes are much smaller, simpler organisms and were amongst the first living thing in existence. ==Eukaryote Cells== [image:http://i.imgur.com/wMxZd9e.png?1] Eukaryotes, contain a whole series of different specialised cellular structures with particular functions. These structures are known as organelles (little organs). These organelles have different structures depending on their function. Eukaryote cells have a nucleus which is membrane-bound (surrounded by a membrane), unlike prokaryote cells. Plants, animals and fungi are all types of Eukaryotes. ==Some other differences:== [image:http://i.imgur.com/Mrh3oQh.png?1]