Smooth vs Rough Endoplasmic Reticulum
SER vs RER
Cell is the basic functional unit of
life, and it is composed of few organelles inside. Endoplasmic reticulum
is one of the very important structures in a cell, and there are two
major types of it known as smooth and rough. Endoplasmic reticulum is
often abbreviated as ER; hence, smooth type is denoted as SER and the
rough type is symbolized as RER. There are interesting differences in
structures and functions between these two types and, this article
summarizes most of those.
Smooth Endoplasmic Reticulum
Smooth endoplasmic reticulum (SER) is
named because of its smooth surface. The surface is smooth because there
are no ribosomes. The structure of SER is a branching network of
tubules and vesicles. These networks structures are important to
facilitate newly synthesized proteins to be folded correctly. In
addition, it contributes to maintain the volume of a cell at a certain
level.
Usually, the location that SER is mostly
found is close to the nuclear envelope. SER plays important roles in
many cellular metabolic processes in a cell such as lipid and steroid
synthesis, carbohydrate breakdown, and regulating the calcium levels.
Additionally, the detoxification of drugs and steroid metabolism have
also been performed with SER in cells. SER assists the cellular
functions such as gluconeogenesis with the presence of
glucose-6-phosphatase enzyme. The network structure provides an
increased surface area to store and put into effect some important
enzymes. The products of those processes are also stored inside the SER
structures. SER has been proven for its importance to attach receptors
on proteins in the cell membrane. Furthermore, SER functions differently
depending on the type of tissue, but above mentioned functions are
usual at most of the times.
Rough Endoplasmic Reticulum
Rough endoplasmic reticulum (RER) is the
ER with ribosomes present on the surface. Because of the presence of
ribosomes, the whole structure appears rough, and it is so named.
Ribosomes are attached to the surface with ribophorin, a glycoprotein
receptor. In addition, this binding is not permanent, but it keeps bound
and released always, except while a protein is being synthesized where
the ribosome is always bound to ER.
The structure of RER is a large network
of tubules and vesicles. It should be noted that the RER surface is
connected with the nuclear envelope or in other words, it looks like an
extension of the nuclear envelope. The basic functions of RER include
the facilitation of sites to synthesize protein, a reserve of cell
membranes, and formation of lysosome enzymes. In addition, its structure
contributes to maintain the stability to the body of the cell.
What is the difference between Smooth and Rough Endoplasmic Reticulum?
• RER has ribosomes on the surface but, not in SER. Therefore, RER is observed as rough while SER as smooth in the microscope.
• SER is attached to the nuclear envelope while RER is continuous with the nuclear envelope.
• RER contributes for the protein synthesis more than SER does.
• RER mainly functions as providing home
for ribosomes to produce, whereas SER serves several other functions
such as detoxification, metabolism, and steroid synthesis.
• The structure of RER is larger than SER.
• RER is a reserve of cell membranes, as
it provides extra cell membrane portions whenever is needed, but SER
does not often do it.
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