In biology, the debate of multicellular vs unicellular organisms is what led to the discovery of the composition of all living organisms on the planet. Every living thing has cells within their body, and these are the building blocks of all life forms. The composition, distribution and the number of cells that are present in an organism determine where they lie in the multicellular vs unicellular spectrum. Cells in the human body play a vital role in the sustenance of life.
In simple terms the difference between unicellular and multicellular organisms arises from the number of cells that are present in them. As the name suggests, unicellular organisms contain one single cell, while multicellular organisms contain more than one cell within them. Multicellular vs unicellular organisms can thus be differentiated on this basis alone. All their physical characteristics and traits can be traced to this difference in the number of cells they contain. Read more about the parts of a cell.
Due to the presence of only one cell in them, unicellular organisms are much smaller in size and are very simple in structure. All unicellular organisms fall under the category of ‘prokaryotes’, or ‘prokaryotic entities’, because their composition and structure is not complex at all. The structure known as the cell nucleus is completely absent in these organisms, and this leads to their inability to handle their surface area to volume ratios. Owing to this reason, their sizes are very small. The differences between multicellular vs unicellular can be accurately traced to the difference in their sizes.
Most unicellular organisms are so small and microscopic in nature, that they are almost invisible to the naked human eyes. They do not have internal organs as well, and this means that the membranes which are organic coats around the organs are also absent. Due to their highly simplistic life form, unicellular organisms can exist in areas that are perceived to be hazardous for human life and are highly acidic or radioactive in nature. Read more about the cell membrane function and cell membrane structure.
It is believed by many scientists that the human race is the result of long term evolution of many unicellular organisms that existed millions of years ago. Multicellular and unicellular organisms exist in harmony with each other on our planet, and all these organisms have their own specific roles to play in nature’s ecosystem.
Examples of unicellular organisms: All forms of bacteria, amoeba, yeast and paramecium.
On the other hand, multicellular organisms are those forms of life that have more than one cell present in them. In fact they have millions of cells present in them. All the differences between multicellular vs unicellular organisms are direct results of the number of cells that are present within their bodies.
The larger number of cells means that these organisms are much bigger in size and are very complex and intricate in their composition and structure. Human beings are the best example of multicellular organisms, and the large number of cells leads to the birth of many different organs for carrying out different functions. These are also known as ‘eukaryotes’ or ‘eukaryotic entities’. The cell nuclei are present in these organisms and the DNA of the organisms are separately placed, unlike the case of unicellular organisms. All these cells work in tandem with each other to keep the life form alive, and this leads to a variety of complex functions working simultaneously. Read more about the similarities between prokaryotic and eukaryotic cells.
Multicellular organisms vs unicellular organisms differ greatly in their appearance, and even though multicellular organisms grow to large sizes some of them are still microscopic in nature. These are also known as ‘myxozoa’.
Examples of multicellular organisms: Human beings, animals, plants, myxozoa and all kinds of fungi.
Scientists discovered all the differences between multicellular organisms and unicellular organisms and this laid the foundation for the rest of biology to develop. The advanced study of the structure of all animals and plants would not be impossible without proper knowledge about the cell structure of these organisms, since the cells are the primary life force and no organism can be alive without the presence of cells in them.
The desire to know the differences between multicellular vs unicellular organisms is an important event in human history, and medical science would not be where it is today without this discovery.