Endoplasmic reticulum

TOPIC# 4 ENDOPLASMIC RETICULUM

INTRODUCTION

It is a type of organelle present in cytoplasm.When we look at cytoplasm under Electron microscope we see a network of channels running through the cytoplasm in only Eukaryotic cell.

These channels are open continous with plasma membrane and also appear to be in contact with the nuclear membrane.This whole system is called Endoplasmic reticulum.

SIZE

These channels are vary in size. These are present in form of tubular membranes or spherical one to seperate it from cytoplasmic materials of cytoplasm.

These membranes are called CISTERNAE(singular cisterna)

FORMS OF ENDOPLASMIC RETICULUM

There are two forms of Endoplasmic reticulum.

1-ROUGH ENDOPLASMIC RETICULM(RER):

It is called rough because on it surface a tiny type of organelle is present called as Ribosome.

RER is continous with nuclear membrane or in other words it is adjacent to nuclear membrane.

It involved in protein synthesis because it has ribosome which is the fundamental organelle for the protein synthesis so in this way it help in protein synthesis because it provide place for ribosome and aslo transport or export the newly made Proteins.

COMPOSITION OF RER:

It is composed of Protein and lipids.

FUNCTION OF RER:

It have two main functions.

1- Synthesis of proteins

2-Secretion of Enzymes

MCQ POINT

It is abundant in rapidly growing cells.

2- SMOOTH ENDOPLASMIC RETICULUM(SER):

It is the 2nd morphological form of Endoplasmic reticlum.

It is adjacent or discontinous with Nuclear Membrane means not in personal contact with nuclear membrane and it is mostly nearer to cell membrane while RER is in personal contact with Nuclear membrane.

FUNCTION OF SER:

It is involve in different kind of functions which are given below:

1-Synthesis of lipids(steroids).

2-Involved in transport of materials within cell.

3-Hormone corticosteroids made in adrenal cortex and sex hormones like testosterone and estrogen are also initiated by Smooth endoplasmic reticulum.

4-Provide mechanical support to cell also help in maintainance of shape.

5-Impulse transmission

6-Detoxification of harmful drugs.

7-SER make lipids from fattyacid and glycerol absorbed in gut and passes to them to another organelle called Golgi bodies which the proceed it and packed it and then transpot or export it outside of the cell.

OVERALL FUNCTION OF ENDOPLASMIC RETICULUM

1-Circulation of materials.

2-Synthesis of Proteins.

3-Synthesis of lipids.

4-Detoxification of drugs.

5-Mechanical support

6-Communication between different organelles and with outside enviornment of cell.

IMPORTANT MCQS IN THIS TOPIC

1-The membranic channels present in cytoplasm above each other called as:

Answer: CISTERNAE while whole system is called ER

2-In Eukaryotic Cells ER are seen with which microscope:

Answer: ELECTRON MICROSCOPE