Endoplasmic reticulum (ER)
Endoplasmic reticulum (ER) is an extensive network of membrane-bounded spaces or channels that occur throughout the cytoplasm mainly endoplasm. This note contains detail information about structure types and functions of ER.
Summary
Endoplasmic reticulum (ER) is an extensive network of membrane-bounded spaces or channels that occur throughout the cytoplasm mainly endoplasm. This note contains detail information about structure types and functions of ER.
Things to Remember
- Endoplasmic reticulum (ER) is an extensive network of membrane-bounded spaces or channels that occur throughout the cytoplasm mainly endoplasm.
- It is absent in prokaryotes and present in all eukaryotic cells except RBC, germinal cells.
- It is well developed in metabolically active cells like pancreatic cells, liver cells.
- It forms cell circulatory system and helps in transportation of materials inside the cytoplasm.
- It acts as cytoskeleton and gives mechanical support.
- It helps in compartmentalization of cytoplasm for synthetic activity.
- These cell organelles form primary lysosomes.
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Endoplasmic reticulum (ER)
It is an extensive network of membrane-bounded spaces or channels that occur throughout the cytoplasm mainly endoplasm. It is absent in prokaryotes and presents in all eukaryotic cells except RBC, germinal cells. It is well developed in metabolically active cells like pancreatic cells, liver cells.
On the basis of presence or absence of ribosomes ER is categorized into two types;
- Rough ER (RER)
- Smooth ER (SER)
| Rough ER | Smooth ER |
| It contains ribosome on the membrane. | It does not contain any ribosome. |
| It lies towards the nuclear membrane. | It lies towards cell membrane. |
| It mainly consists of cisternae. | It mainly consists of tubules. |
| It occurs in protein synthesizing cells. | It occurs in lipid synthesizing cells. |
Structure of ER
The endoplasmic reticulum is composed of three kinds of structures
- Cisternae
- Vesicles
- Tubules
Cisternae
Cisternae are elongated, flattened unbranched membrane-bounded sac-like structure which is placed one above another in a parallel bundle. It occurs mainly towards the nuclear membrane.
Vesicles
Vesicles are oval or rounded membrane-bounded vacuole-like structure which is isolated in the cytoplasm.
Tubules
They are elongated, branched tube like structure which joins with cisternae and vesicles to form a network.
Functions of ER
- It forms cell circulatory system and helps in transportation of materials inside the cytoplasm.
- It acts as cytoskeleton and gives mechanical support.
- It helps in compartmentalization of cytoplasm for synthetic activity.
- These cell organelles form primary lysosomes.
- It forms desmotubule in plasmodesmata between adjoining cells.
- It forms nuclear envelope during cell division.
- It helps in protein synthesis.(RER)
- It helps in lipid synthesis. (SER)
- It helps in glycogenolysis.(SER)
Lesson
Cell organelles
Subject
Biology
Grade
Grade 11
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