. Pick one organelle and describe the role it plays in the life of the cell.

Mitochondrion: Responsible for producing ATP(from NADH and FADH2 resulting from glycolysis and and Krebs cycle of respiration) using its inter-membrane that holds a set of enzymes called collectively the electron transport chain and ATPsynthase that direclty form ATP thru oxidative phosphorelation. Because of this function, muscle cells and other cells that need big amounts of energy are richer in mitochondria than other cells that do no need much energy. Another important function of the mitochondria is that its vital in the process of apoptosis. when apoptosis is needed, the mitochondria release enzymes of the electron transport chain, especially to the cytoplasm of the cell. this results in the mitochondria's inability to respire resulting in cell death.

The Nucleus is a membrane-enclosed organelle found in most eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression.

The main structural elements of the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and keeps its contents separated from the cellular cytoplasm, and the nuclear lamina, a meshwork within the nucleus that adds mechanical support much like the cytoskeleton supports the cell as a whole. Because the nuclear membrane is impermeable to most molecules, nuclear pores are required to allow movement of molecules across the envelope. These pores cross both membranes of the envelope, providing a channel that allows free movement of small molecules and ions. The movement of larger molecules such as proteins is carefully controlled, and requires active transport facilitated by carrier proteins. Nuclear transport is of paramount importance to cell function, as movement through the pores is required for both gene expression and chromosomal maintenance.

Although the interior of the nucleus does not contain any membrane-delineated bodies, its contents are not uniform, and a number of subnuclear bodies exist, made up of unique proteins, RNA molecules, and DNA conglomerates. The best known of these is the nucleolus, which is mainly involved in assembly of ribosomes. After being produced in the nucleolus, ribosomes are exported to the cytoplasm where they translate mRNA.

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