Cell

CELL

A cell is the basic unit of life. All life are made up of cells. All living organisms are thus made up of cells. Cells are capable of independent existence. Anything less than a complete structure of a cell does not ensure independent living. Hence, the cell is the fundamental structural and functional unit of all living organisms. There are two distinct types of cells: Prokaryotic cells and Eukaryotic cells.

CELL THEORY

The Cell theory was given by Schleiden and Schwann.

The main principles of cell theory are:

All living organisms are composed of cells and products of cells.

All cells arise from pre-existing cells

PROKARYOTIC CELL VS EUKARYOTIC CELL

’Pro’ means old and ‘Eu’ means new. So, the first point to remember is that Eukaryotic cells evolved from Prokaryotic Cells. Basic difference is that Eukaryotic cells have a membrane bound nucleus, whereas prokaryotic cells do not have any membrane covering their nucleus. Thus, in Eukaryotic cells, there is compartmentalisation of cell organelles.

Prokaryotic Cells

Prokaryotes have a cell wall surrounding the cell membrane except in mycoplasma. The fluid matrix filling in the cell is the cytoplasm. There is no well-defined nucleus. The genetic material is basically naked, not enveloped by a nuclear membrane. In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria have small circular DNA outside the genomic DNA. These smaller DNA are called plasmids. The plasmid DNA confers certain unique phenotypic characters to such bacteria. One such character is resistance to antibiotics. Examples of prokaryotic cells are- Bacteria, blue-green algae, mycoplasma, etc.

Eukaryotic Cells

They have extensive compartmentalisation of cytoplasm through the presence of membrane bound organelles. They possess an organised nucleus with a nuclear envelope. Their genetic material is organised into chromosomes.

Differences