sandpaper
An everyday object that is similar to endoplasmic reticulum would be a road. Trucks travel on the road like the proteins travel through the endoplasmic reticulum. Assembly line, digestive track or airplane route could be used too.
You can think of the endoplasmic reticulum in a cell as a system of hallways and rooms for transporting and modifying molecules. Similarly, in a house, you can use hallways and rooms to move and process items. Just as the endoplasmic reticulum is crucial for protein production in cells, rooms in a house can be designated for specific tasks, like a kitchen for cooking or a study for working. Both the endoplasmic reticulum and a house's layout serve as organized systems for efficient functions.
Some parts of the ER have ribosomes attached to the cutoplasmic side of the membranes. This is called the RER (Rough Endoplasmic Reticulum). These ribosomes synthesise proteins which are to be secreted from the cell, to form lysosomes or to become part of the cell surface membrane. Other parts of the ER have no ribosomes attached: SER. The cisternae (enclosed spaces in the membranes) of SER tend to be more tubular, in contrast to the flattened sacs of RER. SER has many different functions, including the synthesis of cholesterol and of steroid hormones such as testosterone and the breaking down of toxins such as drugs.
..... If you have a household runway maybe
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Armchair
a remote controler
If you mean the SER, then you can say it is like hallways in a house. It is believed that messenger RNA travels from the nucleus to places where it is decoded by way of the SER. If you mean the RER, it is like the workers who gather in regions of the pizza store where assembly takes place.
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