A cell biologist compared the properties of rough endoplasmic reticulum (ER) and smooth ER. She found that one type of ER is used for protein storage, and the other is used for lipid storage. What accounts for this difference?
a
Rough ER has ribosomes on its surface.
b
Smooth ER creates amino acids for ribosomes to form into proteins.
c
Rough ER forms proteins and transports them to the mitochondria.
d
Smooth ER works with the nucleus to synthesize protein.
The correct answer is a) Rough ER has ribosomes on its surface.
The correct answer is a) Rough ER has ribosomes on its surface.
The correct answer is a) Rough ER has ribosomes on its surface.
To understand why rough ER is used for protein storage and smooth ER is used for lipid storage, it is important to understand the structural differences between the two types of ER.
The rough ER gets its name from the presence of ribosomes on its surface, which give it a rough appearance when observed under a microscope. These ribosomes are responsible for protein synthesis. Ribosomes are the cellular structures where proteins are assembled by linking amino acids together based on the instructions encoded in the DNA.
On the other hand, smooth ER does not have ribosomes on its surface. It appears smooth under a microscope. The absence of ribosomes means that smooth ER is not involved in protein synthesis directly.
The presence of ribosomes on rough ER allows it to actively participate in protein synthesis, folding, and modification. After the proteins are synthesized, they are often processed and packaged within the rough ER before being transported to other locations in the cell, including the Golgi apparatus and the cell membrane. This makes rough ER well-suited for protein storage and transport.
In contrast, smooth ER is involved in the synthesis of lipids, including cholesterol and phospholipids. It also plays a crucial role in detoxifying various substances in the cell, such as drugs and alcohol. The absence of ribosomes on smooth ER gives it a smooth appearance and allows it to specialize in lipid storage and detoxification processes.
Therefore, the key difference between rough ER and smooth ER is the presence of ribosomes, which accounts for the different functions and properties of these two types of ER.