Prokaryotic Cells

Prokaryotic Cell: The cell is the smallest unit of a living entity, the cell is the foundation of all life. There are some species with only one cell, like bacteria. Then there are species with 100 trillion cells or more, like humans. All the different cells have the same chemical composition but carry because of the expression of other genes according to the environment or requirement of the cell. The cell is of two types i.e. Prokaryotic and Eukaryotic cells.

Prokaryotic Cell Definition

Prokaryotic cells are those primitive cells which don’t have a true nucleus and membrane-bound organelle.

Table of Contents
About
Characteristics
Diagram
Structure
Components
Reproduction
Examples
FAQ’s

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

Prokaryotic Cells Examples 

Examples of prokaryotic cells are primitive Bacterial cells and archaebacteria.

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 have chlorophyll inside and they can do photosynthesis and make their own food. In the aquatic environment, they are the Primary producer.

Prokaryotic Cell Structure

• Prokaryotic cells doesn’t have a nucleus but it contains genetic material. 
• Cell  Envelope: The cell envelope is a combination of the cell membrane, cell wall, and outer membrane if it is present. Prokaryotes like bacteria exhibit this envelope. It consists of a bacterium’s cell wall and inner cell wall. The integrity of the cell’s structure is provided by the cell envelope.
• Glycocalyx: Prokaryotic cells are covered in a layer of glycoproteins and glycolipids called the glycocalyx. Although the composition varies depending on the species and the environment, all bacteria secrete a glycocalyx. The glycocalyx has a number of functions, including desiccation resistance, nutrition storage, substrate adherence, surface enhancement (biofilm development), and resistance to phagocytosis. Layers of bacterial populations attaching to a substrate (or host cells) that is covered with a typical glycocalyx make up a biofilm.
• Cell wall: It is below the Glycocalyx and is formed of peptidoglycan. Its work includes giving the bacteria structure and structural support as well as preventing them from bursting or collapsing.
• Flagella: Flagella, which are present in various eukaryotes as well as prokaryotes, are largely used for cell motility. A filament in the prokaryotic flagellum spins to propel the cell forward. A prokaryote may have one or more flagella, which may be confined to one pole or may be dispersed throughout the cell.
• Pilli: Prokaryotic cells have a small, hair-like structure called pili on their surface. Although they can play a part in mobility, their involvement in adhesion to surfaces, which promotes infection, is a crucial virulence trait.
• Plasmids: A plasmid is a type of double-stranded, circular, tiny DNA molecule that differs from a cell’s chromosomal DNA. Both bacterial and certain eukaryotic cells naturally contain plasmids. Plasmid genes frequently provide genetic advantages to bacteria, such as antibiotic resistance. 
• Nucleoid Region: In prokaryotic cells, DNA is found in the nucleoid area. The cytoplasm contains the nucleoid, which is without a membrane. In addition to DNA, the nucleoid area also contains RNA and proteins, including enzymes. 

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. 

Components of Prokaryotic Cell

• Plasma Membrane: A prokaryotic cell’s cytoplasm is encased by a lipid bilayer called the plasma membrane. The cytoplasm is physically isolated from the outer world by it. Additionally, the plasma membrane functions as a barrier that regulates what enters and leaves the cell in a selectively permeable or semipermeable manner.
• Cytoplasm: Cytoplasm in prokaryotes, which are cells without nuclei, is the entirety of the plasma membrane. The gel-like cytosol, a water-based fluid containing ions, tiny molecules, and macromolecules, is a significant part of the cytoplasm in both prokaryotes and eukaryotes.
• Ribosomes: 80S ribosomes are found in eukaryotes while 70S ribosomes are found in prokaryotes. RNA makes up around 62% of ribosomes, with proteins making up the remaining 38%. Similarities in the structure of free and bound ribosomes are related to protein synthesis.
• DNA: Prokaryotes have circular DNA. DNA formed all the proteins which are required by cells to perform all essential functions.

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.

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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 last. With this gram-staining method, we classified the bacteria into Gram Positive and Gram Negative bacteria

Related Links:

Difference between a prokaryotic cell and eukaryotic cell

FAQs on Prokaryotic Cell

Q1: What is a Prokaryotic Cell?

Answer:

Prokaryotic cells are unicellular primitive cells. These cells don’t have any complex structure. Prokaryotic was taken from the words pro and karyon means before and kernel/nucleus. Prokaryotic consists of eubacteria and archaebacteria. Prokaryotes are having simple structures and do not contain membrane-bound organelles. Prokaryotic cell DNA is not attached to the histone protein while Ek cell has histone protein attached to the DNA.

Q2: What are the Structural Features of Prokaryotic cells? 

Answer:

These are the components of prokaryotic cells,

• Cell wall
• Cell membrane
• Capsule
• Pili
• Flagella
• Ribosomes
• Plasmids

Q3: How do Prokaryotic cells divide? 

Answer:

Prokaryotic cells reproduce asexually. The majority of prokaryotic cells divide via binary fission, which produces two daughter cells from each parent cell.

Q4: Do Prokaryotes have DNA?

Answer:

Yes prokaryotic cells have circular DNA. The DNA is present in the cytoplasm because nuclear membrane is not present in pk cell.

Q5: What is the difference between Prokaryotic and Eukaryotic cells?

Answer: 

Prokaryotic cell are primitive ones and they don’t having cell compartmentalization. Ek cell is a complex structure having true nucleus and other membrane bound organelles.

Q6: Can prokaryotes survive without a cell wall?

Answer:

Nearly all prokaryotes have a cell wall outside of their plasma membrane, a protective structure that enables them to endure harsh conditions. Some eukaryotes do have cell walls while some don’t.