STRUCTURE OF THE CELL

The structural and functional building block of life is the cell. It might be thought of as the fundamental building block of every living activity.

                                

   

Prokaryotic and eukaryotic cells

There are two types of cells found in the living world.

1. Prokaryotes have a very simple structure and no clearly identifiable nucleus (Greek: pro-before, karyon, nucleus). Among these are the different bacteria. 

2. Eukaryotes have more complicated structures and functions, and their nuclei are clearly defined (Greek: eu – true, karyon – nucleus). Eukaryotic cells make up the higher organisms, such as plants and animals.

Nucleus

 The largest organelle in a cell is the nucleus, which is protected in a double-layered nuclear envelope. The endoplasmic reticulum's membranes and the outer membrane are continuous. The two nuclear membranes contain 90 nm-diameter nuclear holes at specific intervals. The products that are produced in the nucleus can freely flow through these pores and into the surrounding cytoplasm. DNA is the genetic information's reservoir and is found in the nucleus. A thick structure called a nucleolus can be found inside the nucleus of eukaryotic cells. 

Mitochondria

The mitochondria are the hubs for cellular respiration and energy metabolism (Greek: mitos, thread; chondros, granule). They have varying sizes and shapes and are thought to be the cell's power centres.

Within the mitochondria is a double membrane system. The smooth outer membrane encloses the organelle entirely. Cristae, or "crests" in Latin, are formed when the inner membrane folds to cover a greater surface area. Matrix or mitosol is the term used to describe the inside chamber of mitochondria.

Endoplasmic reticulum

The endoplasmic reticulum (ER) is the network of membrane-enclosed compartments that runs throughout the cytoplasm.

The ER's rough endoplasmic reticulum is a granular look caused by a major section of the ER being studded with ribosomes.

 In the smooth endoplasmic reticulum, ribosomes are absent. In addition to providing Ca2+ for cellular processes, it is engaged in the synthesis of lipids (triacylglycerols, phospholipids, and sterols) and the metabolism of medications.

Golgi apparatus

A Golgi body, sometimes referred to as a Golgi apparatus, is an organelle found in cells that aids in the processing and packaging of lipid and protein molecules, particularly those that are intended for export from the cell. 

References : ‘Biochemistry’ Satyanarayana and Chakrapani