Smooth Endoplasmic Reticulum
Jared Miller
http://cellbio.utmb.edu/cellbio/ser.htm
An extremely important part of the cells in all plants is the endoplasmic reticulum, or ER. The ER can be broken down into two parts, the smooth and the rough. These two parts are differentiated by the sections which have ribosomes attached. The ribosomes attached to certain parts of ER make it rough. See the diagrams.
Diagram 1:
Diagram 2:
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/rougher.htm
The smooth ER is made up of a series of tubules and vesicles which branch and form a large network. Its functions in the plant are very similar to its functions in the body. This shape is very important to its functions. Because this organelle is smooth and has several folds, it expands to create a large amount of surface area. This surface area enables it to do the majority of its functions. For example, it needs the large surface area to store many key enzymes and their products. In addition, the smooth ER is critical in the synthesis of lipids and membrane proteins as well. This is very different from the rough ER, which helps synthesize other proteins. Another function of this organelle is to store and dispense calcium. The large surface area helps store calcium, then, as the smooth ER contracts, the calcium is released out of the cell. The smooth ER contributes to the health of the cell by interacting with and detoxifying toxic molecules as well. In animal cells, the smooth ER works with the mitochondria to make essential steroids. In plants, the smooth and rough sections of the ER make steroids needed on their own.
The smooth ER must interact with other organelles in the cell, mainly, it must work with the rough sections of the endoplasmic reticulum. Also, it is connected to the golgi apparatus. The smooth ER empties its contents into the golgi's sacs. Also, because the smooth ER synthesizes the lipids and proteins that make up the membrane, it has a direct effect on the status of the plant cell membrane as well. With all of these functions, each essential to the plant cell, we can see the importance of the smooth ER in how the cells of a plant function.
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