Prokaryotic cells are single-celled organisms that lack a true nucleus and membrane-bound organelles. Their genetic material is present in a nucleoid region. They are normally smaller than eukaryotic cells, with a size range of 0.1 to 5 μm in diameter. Prokaryotic cells for example bacteria and archaea have a cell wall and fimbriae and pili can often be found on the surface of bacterial cells. They evolved before the eukaryotic cells and live in nearly all environments on Earth. They have the ability to adapt to diverse environments.
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Prokaryotic Cell Definition
Prokaryotic cells is a single celled organism which don’t have a true nucleus and membrane-bound organelle.
What is Prokaryotic Cell?
The prokaryotic cells were discovered by the scientists Antonie van Leeuwenhoek and Robert Hook. The prokaryotic cells are represented by bacteria, blue-green algae, mycoplasma and PPLO (Pleuro Pneumonia Like Organisms). They are generally smaller and multiply more rapidly than the eukaryotic cells. They may vary in shape and size. They are structurally simple and lack a true nucleus. There is no well-defined nucleus. The genetic material is not enveloped by a nuclear membrane. They also contain ribosomes for protein synthesis and a plasma membrane that surrounds the cell. Prokaryotes often have flagella for movement and pili for attachment. These cells can thrive in a wide range of environments and play essential roles in various ecological processes, including decomposition, nitrogen fixation, and disease.
Characteristics of Prokaryotic Cells
The following are characteristics of prokaryotic cells:
- Prokaryotic cells lack organelles and have no nucleus.
- Prokaryotic cells don’t have membrane-bound organelles.
- They are significantly smaller than eukaryotic cells.
- The Cell wall protects every prokaryotic cell, made up of protein and amino acids.
- Many additionally include a polysaccharide-based capsule or slime layer.
- Prokaryotes frequently have protrusions (protrusions) on their surface.
- They have single chromosomes due to their simple body and they are primitive ones.
Prokaryotic Cell Structure
Prokaryotes are unicellular organisms, such as bacteria and archaea. They vary in shapes and can be spherical, rod-shaped, or spiral. A prokaryotic cell structure is as follows:
- Prokaryotic cells lack a true nucleus and their genetic material ispresent in a nucleoid region.
- They have a cytosol that contains a cytoskeleton that organizes cellular materials.
- They have a single, circular DNA that contains the genetic instructions for the functioning of the cell.
- Most prokaryotic cells have a rigid cell wall that provides structural support and protection.
- They have a plasma membrane, tha semi-permeable barrier that separates the cell’s interior from its external environment.
- The cytoplasm is the gel-like substance within the cell membrane where various metabolic processes occur
- The prokaryotic cells have ribosomes, which are organelles that produce proteins, and vacuoles, small spaces in cells that store nutrients and help eliminate waste.
- Pili are short, hair-like appendages on the surface of some prokaryotic cells that serve various functions, such as attachment to surfaces and conjugation.
- Some prokaryotic cells possess flagella, whip-like structures that allow for motility. Flagella help bacteria move through their environment.
Prokaryotic Cell Diagram
Below is a bacterial diagram showing all the characteristics of prokaryotic cells. In the diagram nucleus membrane is absent and the genetic material is in the cytoplasm which is the main difference between the Prokaryotic cell and Eukaryotic cell
Reproduction in Prokaryotes
Prokaryotes can divide in two ways:
- Sexually
- Asexually
Asexually (Binary fission)
Binary fission, also known as asexual body division into two new bodies. When an organism divides into two halves (cytokinesis) through binary fission, it doubles its genetic material, or deoxyribonucleic acid (DNA), with each new organism receiving one copy of DNA.
Recombination
It is a type of asexual reproduction in which the genetic material of one bacterium is inserted into the genetic material of some other bacteria. This happens via 3 processes:
- Conjugation: One bacteria can exchange genetic material with another directly through the process of conjugation. One bacterium acts as the genetic material giver during conjugation, and another bacterium acts as the recipient. The fertility factor, or F-factor, is a DNA sequence that is carried by the donor bacterium
- Transformation: It is also a type of sexual reproduction in which DNA is taken from the surrounding and bacteria add its DNA to that.
- Transduction: In this process, DNA is transferred to the bacteria via the help of a virus. Example Bacteriophage.
Prokaryotic Cells Examples
Examples of prokaryotic cells are primitive Bacterial cells and archae bacteria.
Bacteria
Bacteria are the unicellular simple cell. Bacteria are present everywhere on Earth. The size and shape of bacteria vary. Bactria has pilli and flagella for the locomotion of bacteria. DNA is circular and they also have plasmid (extrachromosomal DNA).
Archaea Cells
These are similar to normal bacteria, but they can survive or be found in harsh conditions because of the composition of the surface layer. The cell wall of archaea don’t have peptidoglycan, they have different types of lipids with different features.
Cyanobacteria
These are the Photosynthetic prokaryotes. They contain chlorophyll and can perform photosynthesis and make their own food. In the aquatic environment, they are the Primary producer.
Gram-staining
The basic dye crystal violet is used to first stain the bacteria. Gram’s iodine solution is then used to treat the bacterium. Then, Gram’s decolorizer, ethyl alcohol, and acetone mixture are added. Safranin, a counterstain that is actually a basic dye, is applied in the last. With this gram-staining method, we classify the bacteria into Gram Positive and Gram Negative bacteria.
Related Links:
- Difference between a prokaryotic cell and eukaryotic cell.
- Prokaryotic Cells and Eukaryotic Cells
- Overview Of Cell Biology
FAQs on Prokaryotic Cell
1. What is a Prokaryotic Cell?
A prokaryotic cell lacks a true nucleus and membrane-bound organelles. It comprise bacteria and archaea that are characterized by a simple structure with a cell wall, nucleoid, and plasma membrane.
2. What are the Structural Features of Prokaryotic cells?
Prokaryotic cells lack a true nucleus and membrane-bound organelles and contains genetic material in a nucleoid. It have a cell wall, plasma membrane, ribosomes, and may contain flagella, pili, and sometimes a protective capsule or slime layer.
3. How do Prokaryotic cells divide?
Prokaryotic cells divide through binary fission and the cell’s DNA replicates and splits into two genetically identical daughter cells. This asexual mode of reproduction is characteristic of bacteria and archaea.
4. What is the difference between Prokaryotic and Eukaryotic cells?
Prokaryotic cells lack a true nucleus and membrane-bound organelles, while eukaryotic cells have a defined nucleus and membrane-bound organelles.
5. Why is the process of cell division in prokaryotic cells different from that in eukaryotes?
The process of cell division in prokaryotic cells is different from eukaryotes because prokaryotes lack a defined nucleus and complex organelles, and their cell division, called binary fission, is a simpler, asexual process without mitosis or meiosis.