Eukaryotic Cell

An eukaryotic cell is a cell whose DNA genetic material is contained in a nucleus, which is also enveloped by a membrane. It also has organelles which perform different biological functions as they float in the cytoplasm. They are the mitochondrion, Golgi apparatus, endoplasmic reticulum, ribosome, lysosome, and the vacuole. The nucleus and the organelles are what differentiate the eukaryotes from the prokaryotic cells. The outstanding cell organelle is the mitochondrion, which provides the cell with energy, in the form of ATP (adenosine triphosphate). But what makes the mitochondrion unique is the fact that it has its own genetic materials, which, like the cell, is also enveloped by a two-layer lipid membrane; thus, it is a cell within a cell in a perfect and harmonious state of symbiosis. This ATP-producing power plant made possible the emergence of multi-cellular organisms and their evolution. A nerve cell in our brain contains around 3,000 mitochondria.

The ribosome is an intracellular ribonucleoprotein, which means it is composed of ribonucleic acid (RNA) and protein. Its main function is protein synthesis. Ribosomes are found in large numbers as they are either bound to the endoplasmic reticulum or free in the cytoplasm. They may occur singly or in clusters. The Golgi apparatus, on the other hand, is a network of stacked membranous vesicles which stores and modifies proteins and other macromolecules, packs them up with a layer of glycoprotein, and then transports them within the cell or excretes them from the cell. The lysosome is a sac-like structure, which is surrounded by a single membrane and contains hydrolytic enzymes; the lysosome breaks down and digests loose materials in the cytoplasm; it also regulates apoptosis (programmed cell death). The endoplasmic reticulum is a network of tubular membranes found within the cytoplasm of the cell, occurring either with a smooth surface (smooth endoplasmic reticulum) or studded with ribosomes (rough endoplasmic reticulum), involved in the transport of materials from the nucleus to the Golgi apparatus.

The genetic material of the nucleus of eukaryotes is organized into chromosomes that are capable of duplication and distribution through mitosis between daughter cells. The molecular basis of the chromosomes is deoxyribonucleic acid (DNA), which is closely associated with histones and other proteins. In most eukaryotes there is a typical sexual process, with the fusion of cell nuclei during fertilization and reduction division during meiosis. The eukaryotic cell nucleus, in turn, contains a nucleolus, which a small rounded body which contains RNA and proteins and is involved in the production of ribosomes.