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Specific Information
- A fairly large and extensive organelle is the endoplasmic reticulum. The endoplasmic reticulum is a complex series of folded or sort of crumpled membranes. It is connected to the membrane that surrounds the nucleus and extends out into the cell's cytoplasm. In doing so, it establishes a chemical communication pathway between the nucleus and the cytoplasm. One of its critical functions is to transport proteins within the cell. An organelle that is somewhat similar to the endoplasmic reticulum is the so-called Golgi apparatus. It functions in a similar way except that it specializes in preparing materials, like proteins, for transport through the cell membrane to the exterior of the cell.
- All the organelles and functions of the cell need energy to operate. And this energy is provided by biochemical processes that occur in the organelle call the mitochondrion. The mitochondrion (singular of mitochondria) is a compartmentalized organelle where aerobic (oxygen-using) respiration occurs. The energy extracted in the mitochondria by metabolizing a food source such as glucose is essential to the functioning of all the other organelles in the cell.
- Although most organelles occur both in plant and animal cells, there is one organelle---the centriole---that occurs only in animal cells. The centriole's function, although not completely understood, is involved with cell division. In a way, the converse of the centriole in the animal cell is the chloroplast in the plant cell. Plant cells have chloroplast and animal cells do not. Even though plant cells do not contain chloroplast, the chloroplast is a vitally important organelle to most of the familiar organisms on earth, including humans. This is because the chloroplast---functioning in concert with all the other organelles in the plant cell---converts the energy from sunlight into chemical energy that plants and animals the world over are dependent upon for their survival.
In General
Organelles serve specific functions within eukaryotes, such as energy production, photosynthesis, and membrane construction. Most are membrane-bound structures that are the sites of specific types of biochemical reactions. The nucleus is particularly important among eukaryotic organelles because it is the location of a cell's DNA. Two other critical organelles are mitochondria and chloroplasts, which play important roles in energy conversion and are thought to have their evolutionary origins as simple single-celled organisms.
Examples
Reproduction
Most cells have to reproduce themselves. In order to do so, many organelles have to work together. This process is called mitosis. The nucleus copies the genetic information, forming an exact duplicate. Then, cytoskeletal elements, which form some of the structure of the cell and act like a combination of skeleton and muscle, pull the two copies of the genes away from one another. Finally, the cell's membrane splits into two, dividing the cell into equal and complete halves.
Most cells have to reproduce themselves. In order to do so, many organelles have to work together. This process is called mitosis. The nucleus copies the genetic information, forming an exact duplicate. Then, cytoskeletal elements, which form some of the structure of the cell and act like a combination of skeleton and muscle, pull the two copies of the genes away from one another. Finally, the cell's membrane splits into two, dividing the cell into equal and complete halves.
Protein Synthesis
Almost all cells make protein, whether it's for their own use or to export as a product. A variety of organelles coordinate their activities to this end. The nucleus of the cell is an organelle that contains DNA, or genetic information. It must produce a working copy of that information, called RNA, which it ships out into the rest of the cell. Then organelles called ribosomes, which are often located attached to organelles called the rough endoplasmic reticulum, make protein by reading the RNA.
Almost all cells make protein, whether it's for their own use or to export as a product. A variety of organelles coordinate their activities to this end. The nucleus of the cell is an organelle that contains DNA, or genetic information. It must produce a working copy of that information, called RNA, which it ships out into the rest of the cell. Then organelles called ribosomes, which are often located attached to organelles called the rough endoplasmic reticulum, make protein by reading the RNA.
Importation and Exportation
Cells need to be able to bring in nutrients and export products. There are additional organelles that coordinate their activities to achieve these goals. The cell membrane folds inward, forming an invagination, to draw in food or liquid particles. Resulting small bubbles of food inside the cell fuse with digestive organelles called lysosomes. An organelle called the Golgi complex, exports cellular products, working in tandem with the rough endoplasmic reticulum.
Cells need to be able to bring in nutrients and export products. There are additional organelles that coordinate their activities to achieve these goals. The cell membrane folds inward, forming an invagination, to draw in food or liquid particles. Resulting small bubbles of food inside the cell fuse with digestive organelles called lysosomes. An organelle called the Golgi complex, exports cellular products, working in tandem with the rough endoplasmic reticulum.