Struture and Functions of Enzymes
Cells are the structural and functional units of all living organisms; each specialised to perform dedicated duties throughout their life span. All living organisms can be sorted into one of two groups depending on the fundamental structure of their cells. These two groups are the prokaryotes and the eukaryotes. A Prokaryote cell is the first form of cells for many millions of years until the eukaryote cell evolved from the prokaryote cell, which created life. Prokaryote cells are organisms made up of cells which lack a cell nucleus or any membrane encased organelles, which means the DNA in prokaryotes is not bound with a nucleus. In the eukaryotes, DNA is organized into chromosomes, which is surrounded by a membrane. According to Dr Lynn Margulis (2005), she states that the origins of mitochondria and chloroplasts which are organelles of eukaryotic cells. This means that the mitochondria and chloroplasts were prokaryotic cells, which entered the eukaryotic cells and co-existed through endosymbiosis.
There are many organelles inside a eukaryote cell, each performing dedicated functions. For example, the nucleus, this is a membrane bound structure containing DNA and other genetic information. The mitochondria reserve and convert energy into form usable by the cell. They are known as the power houses of cells. The plasma membrane is also another important structure in a cell.
The plasma membrane is the structure of the cells which define and enclose the cell. The membrane forms a barrier between the inside and the outside of the cell, enabling different chemical environments to exist on each side of it. The cell membrane is made up of phospholipid bilayers, carbohydrates and proteins arranged in a fluid mosaic structure. There are five main methods by which substances can move across a cell membrane; these are lipid diffusion, osmosis, passive transport, active transport and vesicles. (BiologyMad, 2004)
See Appendix 1 (Eukaryote Cell)
The egg cell
There are many organelles inside a eukaryote cell, each performing dedicated functions. For example, the nucleus, this is a membrane bound structure containing DNA and other genetic information. The mitochondria reserve and convert energy into form usable by the cell. They are known as the power houses of cells. The plasma membrane is also another important structure in a cell.
The plasma membrane is the structure of the cells which define and enclose the cell. The membrane forms a barrier between the inside and the outside of the cell, enabling different chemical environments to exist on each side of it. The cell membrane is made up of phospholipid bilayers, carbohydrates and proteins arranged in a fluid mosaic structure. There are five main methods by which substances can move across a cell membrane; these are lipid diffusion, osmosis, passive transport, active transport and vesicles. (BiologyMad, 2004)
See Appendix 1 (Eukaryote Cell)
The egg cell
References: BiologyMad, (2004) cell structure, [Online] Accessed on http://www.biology-online.org/9/2_cell_structure.htm (Retrieved on 14.11.12) Etel Gray,H(1821-1865) Anatomy of the Human Body, [Online] Accessed on http://www.bartleby.com/107/3.html (Retrieved on 12.11.12) Maupin Shaw, L (2005). Access to HE anatomy and physiology. CHELTENHAM: Nelson Thomas LTD (pp17-103) Bibliography BiologyMad, (2004) cell structure, [Online] Accessed on http://www.biology-online.org/9/2_cell_structure.htm Etel Gray,H(1821-1865) Anatomy of the Human Body, [Online] Accessed on http://www.bartleby.com/107/3.html Maupin Shaw, L (2005). Access to HE anatomy and physiology. CHELTENHAM: Nelson Thomas LTD (pp17-103)