Introduction to Cell Structure and cell Organelles

Cell is the simplest unit of life. Every living organism is made up of one or more cells. Different and enormous number of micro molecules and macromolecules arrange themselves in a particular way to form cells and their organelles.In simple organisms, like bacteria and protists, the entire organism is made up of one cell, but in complex organisms like animals and plants, the body is multicellular.

Organelles are sub-cellular structures that are highly organised discrete structures that have a specific function in the metabolism of cell. There are numerous organelles,each specific for its role such as mitochondria, chloroplast, ribodomes, cytoskeleton, centriloes, Golgi complex, lysosomes, peroxisomes, glyoxysomes, nucleus, chromosome, uncle plus etc. Some organelles may be present in large amounts in particular types of cells in which their is more demand of them for instance, in muscle cells their is large amount of smooth endoplasmic reticulum that function to pump calcium ions for muscle activity.

Occurrence of organelles varies in different types of cells. In prokaryotes (relatively simple cells ), no organelles are found except ribosomes(which are needed to create proteins). Whereas in eukaryotes(complex cells), all membrane bound organelles are found due to their complex functions. (I'll write a separate blog on prokaryotes and eukaryotes)

In some organisms, rather unique cell organelles are found such as in cnidarians(animals of phylum cnidaria) their animals have special kinds of cells called nematocytes, that contain special cell organelles called nematocysts that release certain chemicals used to immobilized the prey (these cells are present in the tentacles of such animals)

Some common organelles and their functions are stated below:

1). Endoplasmic Reticulum: it is a continuous network of elongated closed sacs called cisternae, extending from the membrane of nucleus to the plasma/cell mambrane.Its function is to receive proteins from the nucleus and send them to Golgi complex and also the numerous ribosomes attached to it gives it a function in protein synthesis.

2).Ribosomes: they are spherical non membrneous organelles that function in protein sysnthesis. They are receive message from DNA and translate the code into configuring a protein that is used for various purposes in the cell.

3).mitochondria: they are the power house of the cell. They make the currency of energy used I side cells that is ATPs. They have double membrane covering the outer membrane containing pores for diffusion of proteins and ions. It contains its DNA, enzymes and proteins. Mitochondria are independent from the cell in its needs.