Cell membrane - encloses the contents of the cell and regulates the flow of substances into and out of the cell.
Mitochondrion - this feature produces a substance called adenosine triphosphate (ATP) which is the carrier of energy in all cells.
Centriole - these two features made of hollow tubules play a key role in cell division.
Ribosomes - these small, granular features of the cell play a key role in the assembly of proteins.
Chromosome - During cell division, DNA, the genetic material duplicates and forms linked coils called chromosomes.
Endoplasmic reticulum - this organelle helps to transport materials through the cell. Rough reticulum is the site of attachment for ribosomes; smooth reticulum is the site of fat production.
Nucleolus - this is a small structure inside the nucleus that plays an important role in ribosome production.
Nucleus - this is the cells control centre and it mainly contains chromatin, a granular material composed of DNA, the cells genetic material and proteins. The inner nucleus is made up of RNA and proteins. The nucleus is surrounded by the nuclear envelope, a two-layered membrane with pores.
Golgi complex - A stack of flattened sacs receives and processes protein that has been dispatched by the endoplasmic reticulum. The proteins are modified and released at the cell membrane.
There are four main types of tissue: epithelial, connective, muscle and nervous.
Epithelial tissue is found in skin and in diverse forms has special functions in other areas of the body. The main types are: simple epithelium, a single layer of squamous (flat), cuboidal (cube like), or columnar (tall) cells; stratified epithelium, with two or more layers; pseudostratified epithelium, which looks stratified but has only one layer of columnar cells that have surface hairs (cilia) or secrete mucus; and transitional epithelium, which is multi layered and flexible. [pic]
Connective tissue - the...