The simplest form of cell, prokaryotic cell is also the oldest form of life on the earth. Distinctively known for the cellular structure, prokaryotic cells are those which lack membrane-bound nucleus and other cell organelles.
Structure of Prokaryotic Cell
Microscopic in size, prokaryotic cells are as small as mitochondria in eukaryotic cells and have diameter ranging from 0.1-10µm.
The smallest among the cells, prokaryotic cells have DNA located at the region called nucleoid. Other organelles like ribosome, plastids, chlorosome, etc. are found scattered in cytoplasm. The cytoplasm is covered by the protective layer called plasma membrane, which is further protected by the cell wall. Thread like structures such as pili, fimbria, flagella, etc. are found on the external surface of the cell. They help in transfer of genetic material, attaching to the host cell and locomotion, respectively.
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Eukaryotiv cell is more developed, advance and complex than prokaryotic cells, eukaryotic cells are those with the defined nucleus, along with other membrane-bound organelles.
Structure of Eukaryotic Cell
Although larger than the prokaryotic cells, eukaryotic cells are also microscopic in size having diameter ranging from 10-100µm.
Eukaryotic cells have various cell organelles such as mitochondria, Golgi bodies, endoplasmic reticulum, ribosome, vacuole, etc. Other than these, there may be presence of other cell organelles depending upon the type of the cell.
Similar to the prokaryotic cells, organelles in eukaryotic cells are also held in position by the cytoplasm which is composed of various organic substances. The cytoplasm is entirely covered by the lipid layer called plasma membrane, which is further covered by an extra layer called cell wall (only in plant cells).
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Similarities between Prokaryotic and Eukaryotic Cell
- Although eukaryotic cells are larger than the prokaryotic cells, both of them are visible only through light and electronic microscope.
- Flagellum, the part in prokaryotic cell which helps in locomotion, is also present in unicellular eukaryotic cells.
- Both prokaryotic and eukaryotic cells have DNA as their genetic material.
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Differences between Prokaryotic and Eukaryotic Cell
- Generally, prokaryotic cells are unicellular while most of the eukaryotic cells are multicellular.
- The DNA in prokaryotic cell is not enclosed within the nucleus but the DNA in eukaryotic cell is enclosed inside the nucleus.
- Transfer of DNA in prokaryotic cell occurs through transformation, transduction and conjugation while it occurs through meiosis in eukaryotic cells.
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