The human body is an ecosystem that consists of multiple organs. Cells form the basic structural and functional unit of life. Not only does the cell store DNA but it also consists of multiple cellular components necessary for the working of a human body. Organisms can be broadly divided into two types based on the structure and components of their cells, mainly Prokaryotes and Eukaryotes.
Key ingredients that make up a cell include plasma membrane, cytoplasm, nucleus (majorly the genetic material within), and ribosomes. Single-celled organisms that lack a nucleus and membrane-bound organelles are referred to as prokaryotes and the cell is referred to as prokaryotic cells.
On the other hand, organisms consisting of cells that have a well-defined nucleus and membrane-bound organelles are referred to as eukaryotes and the cell is referred to as a eukaryotic cell.
Prokaryotic Cells
Generally, prokaryotic cells are not divided up inside through membrane walls but have a single open space. The genetic information within a prokaryotic cell is found in a central region of the cell called the nucleoid and appears in form of a large loop called a circular chromosome.
The best example of a prokaryote is bacteria. Most of them however are surrounded by rigid cell walls made up of peptidoglycan, which is a polymer consisting of linked carbohydrates and proteins. The typical prokaryotic cells could range from 0.1-5.0 micrometers in diameter.
Prokaryotes are said to be the earliest and most primitive form of life on earth. They include some archaeans as well. Certain prokaryotic bacteria such as cyanobacteria can also perform photosynthesis.
The distinctive features of prokaryotes also include the fact that they are extremophiles and can thrive in various types of extreme environments including hot springs, swamps, etc.
Eukaryotic Cells
As they possess a well-defined nucleus and membrane-bound organelles they also contain well-defined chromosomes. They hold mitochondria as the powerhouse of the cell which helps in the synthesis of Adenosine Triphosphate (ATP) that supports the energy production of the body.
We are all eukaryotes. Most multicellular organisms are eukaryotes. However, there are certain exceptions for cells like RBC which do not contain mitochondria or nucleus on maturing. It is believed that eukaryotes evolved between 1.7 billion and 1.9 billion. The earliest microfossil depicting eukaryotic cells goes back to 1.8 billion years ago.
Eukaryotic cells are typically much larger than those of prokaryotes, having a volume of around 10,000 times greater than the prokaryotic cell. They have a variety of internal membrane-bound structures, called organelles, and a cytoskeleton composed of microtubules, microfilaments, and intermediate filaments, which play an important role in defining the cell’s organization and shape.
Eukaryotic DNA is divided into several linear bundles called chromosomes, which are separated by a microtubular spindle during nuclear division.
Difference Between Prokaryotic & Eukaryotic Cells
| Eukaryotic Cells | |
|---|---|
| They have membrane-bound organelles. | They do not have membrane-bound organelles. |
| They contain well defined nucleus and the genetic information is within the nucleus. | They do not contain a well-defined nucleus and DNA floats around the cytoplasm. |
| Differentiated cell divisions stages such as Mitosis are present. | Does not contain cell division stages and generally divides through processes like binary fission. |
| Presence of golgi apparatus, lysosomes and mitochondria. | Absence of golgi apparatus, lysosomes, and mitochondria but contain ribosomes. |
| Different folds of the endoplasmic reticulum are present. Eg: Human beings and most multicellular organisms. | No endoplasmic reticulum Eg: Bacteria |
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