the+organelles+of+the+cell

The human cell contains several organs.** An organ is component that performs specific functions for the cell. Organelles maintain the life of the cell. ** The first organelle you would notice is a thin membrane the surrounds the cell called the **__cell membrane__**. The function of this membrane is to keep all the organelles inside the cell and to enable them from leaving the cell. The second most important organelle is the **__nucleus__**. It's the biggest organ in the cell. The nucleus contains all the genetic materials as well as directing all the cells activities. Between the cell membrane and the nucleus lies the **__cytoplasm__**, which contains the various organelles of the cell. The cytoplasm is made of a gelatin-like fluid that is called the cytosol. These are the three basic organelles that are found in all kinds of cells. **__Mitochondria:__** __Mitochondria__ are scattered throughout the cytosol, and they are relatively large in size compared to other organelles. Mitochondria are the site of all the chemical reactions that transmit energy to other parts of the cell that will be used later in chemical reactions.
 * __The Organelles of the Cell__**



**__Ribosomes:__** They are the most numerous but the smallest organs in the cell. Ribosomes are made of organic compounds- proteins and RNA. Ribosomes play an important role in the synthesis of proteins. We have two kinds of ribosomes, the first kind are those that are freely moving in the cytoplasm, and the second are ribosomes that are attached to an organelle called the endoplasmic reticulum.

**__Endoplasmic Reticulum (ER):__** ER is a system of numerous tubules and sacs. The ER acts as an intracellular highway, or a path along which molecules move from one part of the cell to another. The cell usually contains two types of ER, the **rough endoplasmic reticulum** and the **smooth endoplasmic reticulum**. The rough ER, is the one that has the ribosomes attached to it. Rough ER is prominent in cells that make a large amount of proteins to be exported from the cell to the cell membrane.



The smooth ER, does not have ribosomes attached to its surface that's why under a microscope it look smooth. Smooth ER is involved in the synthesis of steroid in gland cells, as well as the regulation of the calcium level and the breaking down of toxic substances by the liver cells.




 * = [[image:https://lh5.googleusercontent.com/-TfS7GSusrzw/TXJjycqFgPI/AAAAAAAAAA0/pg1Do-ytpuk/s1600/images+%25283%2529.jpg align="center" link="https://lh5.googleusercontent.com/-TfS7GSusrzw/TXJjycqFgPI/AAAAAAAAAA0/pg1Do-ytpuk/s1600/images+%25283%2529.jpg"]] ||
 * = rough ER to the left and Smooth ER to the right ||

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Review Questions:

1) Why is the nucleus very important in the cell? 2) What is the kind of energy that the mitochondria transmit through its chemical reactions? 3) What is the major difference between the rough ER and the smooth ER? ** Leen: **  1. The nucleus is very important in the cell because the nucleus contains all the genetic materials as well as directing all the cells activities.

2. The energy transmitted by mitochondria through its chemical reactions is known as the cellular energy.

3. The rough ER has cells that make a large amount of proteins to be exported from the cell to the cell membrane, while the smooth ER is involved in the synthesis of of steroid in gland cells, as well as the regulation of the calcium level and the breaking down of toxic substances by the liver cell s.  Nasser:   1) The nucleus is the most important part of the cell because it contains all the genetic materials, and it directs the cells activities.   2) The energy that the michochondria transmits is called cellular energy, it is caused by chemical reactions   3) -The rough ER has ribosomes atatched to it, and it is prominent in cells that make a large amount of protien that are to be exported from cell to cell membrane.   -The smooth ER does not have ribosomes attached to it, and is involved in the synthesis of steroids in gland cells, it also regulates calcium levels and breaks down   the toxic substances in the liver.