Cell organelles structure and function

Cell organelles are membrane bound little structures that perform activities in the cell. The various cell organelles are – Endoplasmic Reticulum, Ribosomes, Golgi apparatus, Lysosomes, Mitochondria, Plastids, Vacuoles, Peroxisomes and Centrosome.

1. Endoplasmic Reticulum:

The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets which looks like long tubules or round or oblong bags (vesicles). There are two types of ER– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has ribosomes attached to its surface. The ribosomes are the sites of protein manufacture. The SER helps in the manufacture of fat molecules or lipids. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis. Some other proteins and lipids function as enzymes and hormones.

Functions:

1. 1. It serves as channels for the transport of materials between various regions of the cytoplasm or between the cytoplasm and the nucleus.
   2. The ER also functions as a cytoplasmic framework providing a surface for some of the biochemical activities of the cell.
   3. SER plays a crucial role in detoxifying many poisons and drugs.
   4. It forms supporting skeletal framework of the cell.
   5. Golgi Apparatus:

   6. The Golgi apparatus was first described by Camillo Golgi. Golgi apparatus consists of a set of membrane-bounded, fluid filled vesicles, vacuoles and flattened cisternae. Cisternae are usually stacked together (placed one above the other) in parallel rows. Golgi apparatus exists as an extensive network near the nucleus in the animal cells. However, the plant cells contain many freely distributed subunits of Golgi apparatus, called dictyosomes. The Golgi apparatus arises from the membrane of the smooth endoplasmic reticulum, which in turn, originates from the rough endoplasmic reticulum.

      Functions:

   7. 1. Its functions include the storage, modification and packaging of products in vesicles.
      2. In some cases, complex sugars may be made from simple sugars in the Golgi apparatus.
      3. The Golgi apparatus is also involved in the formation of lysosomes, cell wall and plasma membrane.