Question

Which of the following is a type of endoplasmic reticulum?
(a)Smooth endoplasmic reticulum
(b)Rough endoplasmic reticulum
(c)Both A and B
(d)None of the above

Answer 1

Endoplasmic reticulum is of two types, which are differentiated based on the presence of ribosomes on them. The endoplasmic reticulum is involved in protein synthesis and transportation in the cell.

Complete answer:
The two types of endoplasmic reticulum are smooth endoplasmic reticulum and rough endoplasmic reticulum. The rough endoplasmic reticulum is a participant of the endomembrane system which is in the cell cytoplasm. The formation of protein along with its folding and transportation among organelles for the outside of the cell are done by the rough endoplasmic reticulum. It is called the ‘rough’ endoplasmic reticulum because of the appearance of ribosomes on the outer layer as pebbles under the electron microscope. The smooth endoplasmic reticulum is also a constituent of the endomembrane system that makes various structural lipids such as cholesterol and phospholipids.

Additional Information: -Rough endoplasmic reticulum is present both in plant cells and animal cells, their membrane joins with the nuclear membrane.
- Accumulation of calcium ions is necessary for muscle cells which occurs because of the sarcoplasmic reticulum made by the smooth endoplasmic reticulum.
-Smooth endoplasmic reticulum has a dynamic shape that extends new tubules from both sides. These tubules join with the cells cytoskeletal framework.
So, the correct answer is 'Both A and B'.

Note: -Rough endoplasmic reticulum is majorly formed by flattened sacs called cisternae and other tubules. The translocon protein present on the membrane helps in translation.
-Ribophorin is a group of proteins that helps the ribosomes to get attached to the endoplasmic reticulum.
-The network of tubules majorly constitutes a smooth endoplasmic reticulum and is usually located near the cytoplasmic membrane.