What is a Cell?
A cell is referred as a structural and functional unit of all living organisms. It is derived Latin word meaning small room and was first observed by a Robert Hook – an English natural philosopher in the year 1953. All living beings on this earth are composed of one or many cells that perform their individual functions. These cells are said to be the building blocks of life. During the 1950s, scientists created the concept of prokaryotic cell and eukaryotic cell. Their cells have two basic features: the cell membrane and a plasma membrane.
Prokaryotic cell Vs. Eukaryotic cell
Prokaryotes are unicellular in nature, as they possess a single cell like bacteria and archaea. While few single cell and all multicellular organisms are known as Eukaryotes, although they have the cytoplasm and genetic material in common.
Prokaryotic cell: They happen to be simpler and smaller. A prokaryotic cell doesn’t possess nucleus or other cell organelles. It is derived from a Greek word meaning before nuclei. They are reproduced through nuclear fission. It has a capsule which covers the outside of the wall, a cell wall which provides strength and rigidity, cytoplasm helping in cellular growth and a plasma membrane containing proteins, etc. The cytoplasm region contains ribosomes which are the smallest part and play a vital role in protein synthesis, mesosomes or the folding that help in cellular respirations, plasmids the small circle of DNA, pili, and flagella. Organisms belonging to the kingdom Monera possess prokaryotic cell.
Eukaryotic cell: They are complex and larger than the prokaryotic cells. It is also derived from a Greek word meaning good or true nuclei. They include all life kingdoms except monera. They consist of the cell wall which protects and supports the plasma membrane, the plasma membrane surrounds the cell and controls the entry and exit of certain substances, the nucleus containing DNA that stores all information, nuclear membrane surrounds the nucleus, nucleolus playing a vital role in protein synthesis, mitochondria are involved in performing their cellular functions, chloroplast being the subcellular sites of photosynthesis, endoplasmic reticulum helping in movement of materials, ribosome composed of proteins, Golgi bodies, lysosomes, vacuoles, cytoplasm, chromosomes, and centrosomes.
A difference between Prokaryotic and Eukaryotic Cell:
|Cell and cell size||Always unicellular and the size lies in between 0.2- 2.0 micrometers in diameter||Mostly multi-cellular and the size lies in between 10 – 100 mm in diameter|
|Cell wall||Usually present; chemically complex in nature||When present, chemically simple in nature|
|Nucleus||Is absent||Is present|
|Ribosomes||These cells consist of ribosomes which are smaller in size and circular in shape when compared to the cells of eukaryotes.||The ribosomes of eukaryotes are larger in size and are linear in shape.|
|DNA arrangement||Circular in shape||Linear in shape|
|Mitochondria||Is absent||Is present|
|Cytoplasm||The cytoplasm in prokaryotes does not contain the endoplasmic reticulum||In this, the cytoplasm has the endoplasmic reticulum|
|Plasmids||Present in prokaryotes||Very rarely found in eukaryotes|
|Ribosome||small ribosomes.||large ribosomes.|
|Lysosome||In this, the lysosome, mesosome, and centrosome is absent||Mesosome, Lysosomes, and centrosomes are usually present in Eukaryotes|
|Cell division||Through binary fission||Through mitosis|
|Nucleus||It has no nucleus.||It has a true nucleus, bounded by a double membrane.|
|Flagella||The flagella is smaller in size in prokaryotes||The flagella is larger in size in case of eukaryotes|
|Reproduction||Asexual||Both asexual or sexual|
|Example||Bacteria and Archaea||Plant and Animal cell|
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