Prokaryotic and Eukaryotic Cells: Difference, Characteristics and Structure

Prokaryotic and Eukaryotic are the types of cells that help in the protein synthesis process. Every living organism is composed of one of two groups: eukaryotes or prokaryotes. The cellular structure shows which group an organism belongs to.

• Prokaryotic cells are devoid of membrane-bound organelles and a true nucleus.
• Eukaryotic cells have a well-defined nucleus surrounded by a nuclear membrane consisting of clearly defined chromosomes. 
• According to scientists, eukaryotes evolved from prokaryotes around 2.7 billion years ago.
• The first form of life was prokaryotes.

Read more: Packaging of DNA

Keyterms: Prokaryotic cells, Eukaryotic cells, Protein, Protein synthesis process, Membrane, Nucleus, Chromosomes, Nuclear membrane

Read Also: Proteins 

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What are Prokaryotic Cells? 

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The term 'prokaryote' is derived from the two Greek words pro (means earlier or before) and Karyon (means kernel). It is simply translated before the nucleus.

• The prokaryotic cells are the most primitive cell which was discovered nearly 3.4 billion years ago.
• These prokaryotic cells are found in ancient environments.
• Some of the cells use chemical energy while some of them use solar energy from the sun.
• It can be specified by their internal structure.
• The prokaryotic cells have no nuclear membrane around them.
• The prokaryotic cells are smaller in size and simple structure.
• The organisms consist of prokaryotic cells termed prokaryotes.

These cells have an absence of a nucleus and the reproduction in the organisms made up of prokaryotic cells is done by the binary fission process. The structure of prokaryotic cells has a capsule-like structure that works as a protective layer for the cell.

Important Components of Prokaryotic Cells

The following are the important components of prokaryotic cells:

1. Plasma Membrane - It's an outer layer that covers the cell and separates the cell from the outer environment. It consists of phospholipid molecules.
2. Cytoplasm - It is present inside the cell having a jelly-like structure. The cellular components are found in the cytoplasm. It mainly contains salts and enzymes.
3. Ribosomes - It is one of the important components of prokaryotic cells where protein synthesis occurs.
4. DNA - DNA is the genetic material of the cell circular and directs the protein created by the cells and its functions.

Prokaryotic cells are devoid of nuclear membranes, mitochondria, or Golgi bodies, there are various other components that are a part of the structure which include:

• Nucleoid - The nucleoid is a genetic material present within the cell’s cytoplasm that is generally spherical, rod-like, or spiral-shaped.
• Cell Wall - The wall of the cell is the exterior layer of a cell and provides shape and structure to the cell. 
• Capsule - A capsule helps in the protection of the bacterial cells, retaining moisture and attaching themselves to the different surfaces of nutrients.
• Flagella - Flagella refers to the long tail-like structures that help the prokaryotic cells to move from one place to another.
• Pili - They are fine hair-like structures that are in the form of outgrowths that help the cells to attach themselves to other prokaryotic cells. 

Characteristics of Prokaryotic Cells

The prokaryotic cells have various specific characteristics which are as follows:

1. It does not contain a nuclear membrane or nucleus.
2. The mitochondria, Golgi bodies, and chloroplasts are not found in prokaryotic cells.
3. The genetic material of prokaryotic cells' DNA is circular.
4. The prokaryotic cells have a small size and simple structure. The size of cells ranges from 0.5 to 5 micrometers.
5. Reproduction is done by the Binary fission process.

Examples of Prokaryotic Cells

The most common examples of prokaryotic cells are bacteria, cytoplasm, blue and green algae, amoeba, onion peel cells, plants, animals, fungi, protozoa, etc.

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What are Eukaryotic Cells 

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The term Eukaryotes is derived from the two Greek words EU (means good) and Karyon (means kernel).

• This means the cell has a good nucleus.
• It contains almost all the kingdoms of organisms.
• Eukaryotic cells have larger and more complex structures as compared to prokaryotic cells.
• The cell's nuclear membrane covers the outer surface of the cell called the eukaryotic cell.
• The organisms having a nucleus covered with a nuclear membrane are called eukaryotes.

The eukaryotic cells have a well-organized structure. In these cells, the cytoplasm consists of mitochondria covered with membranes. The eukaryotic cells have sexual and asexual divisions. In the cellular features, eukaryotic cells are a well-organized structure as compared to prokaryotic cells.

Important Components of Eukaryotic Cells

The eukaryotic cells consist of various components. The main components of eukaryotic cells are as follows:

• Plasma membrane - It covers the outer region of the cell and separates the cell structure from the external environment. It is made up of protein contents and exchanges the substances from the cell.
• Cell wall - The cell wall is made from protein, cellulose, and pectins. It is found only in plant cells and absent in animal cells. It works as a protective shield for the cell.
• Nucleus - Nucleus is the main part of the cells where ribosomes are produced. It also contains nucleoplasm having protein and DNA inside it.
• Ribosomes - Ribosomes are found inside the nucleus of cells made up of ribonucleic acid, and protein. The protein synthesis occurs in the ribosome.
• Lysosomes - These consists of hydrologic enzymes that help in the digestion of proteins like nucleic acid, lipids, carbohydrates, etc.
• Mitochondria - It produces energy and maintains the metabolic activities of the cell. It is called the powerhouse of the cell.
• Cytoskeleton - It is located inside the cytoplasm of the cell. It consists of fibers, microtubes, etc. which lend to shape the cell and are responsible for the movement of the cell.
• Golgi bodies - It is situated close to the nucleus of the cell. These are not found in plant sieve cells and human RBCs. It is disc-shaped and plainly structured.
• Endoplasmic Reticulum - It is a network of structures having small and tubular shapes. It is commonly two types - smooth and rough.

Characteristics of Eukaryotic Cells 

The eukaryotic cells have following characteristics mentioned below -

1. The nucleus of eukaryotic cells is covered with the nuclear membrane.
2. The cell wall is the outermost layer of the eukaryotic cells.
3. These cells are split in parts through the mitosis process.
4. It comprises a cytoskeleton structure.
5. Mitochondria is found in each eukaryotic cell.
6. The genetic material found inside the nucleus consists of single and linear-form DNA. 

Read Also: Excretion in Plants

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Difference between Prokaryotic and Eukaryotic Cells

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Given below are the difference between prokaryotic and eukaryotic cells:

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Points to Remember

• Prokaryotes are unicellular organisms that do not have membrane-bound structures.
• Prokaryotic cells help in nutrient recycling by the decomposition of dead organisms and re-using their nutrients.
• They help in a varied number of metabolic processes.
• Eukaryotes are organisms that have a nucleus and other organelles enclosed by a plasma membrane.
• The cell’s DNA is situated in the nucleus among the eukaryotic organelles. 
• Two other important organelles are the chloroplasts and mitochondria.
• The eukaryotic cells help in keeping the disease causing organisms at bay. 

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Previous Year Questions

• The movement of cilia and flagella is due to the presence of...[JKCET 2013]
• Plasma membrane helps in :...[JKCET 2005]
• Which of the following structure is bounded by single membrane?...[JKCET 2005]
• 70 S ribosomes occur in….[AMUEEE 2014]
• Rough endoplasmic reticulum is actively involved in​...[JKCET 2014]
• Perinuclear space is present in...[JKCET 2014]
• Chloroplast lacks….​[COMEDK UGET 2005]
• Colour of flower petals is due to​...[CUCET 2012]
• Streaming of the cytoplasms within some living cell is known as...[CUCET 2011]
• Example of an oxidative organelle is...[CUCET 2011]
• Lampbrush chromosomes are...[COMEDK UGET 2005]
• Cisternae have a diameter of...[JKCET 2014]
• Cells divide and new cells are formed from pre-existing cells. This concept was given by..[AMUEEE 2010]
• Aleuroplasts in a cell stores...[AMUEEE 2010]
• Axoneme having 9 + 2 doublet microtubule arrangement is found in...[AMUEEE 2009]
• One of the chief functions of smooth endoplasmic reticulum is..[AMUEEE 2009]
• Cilia are :...[JKCET 2004]
• Which is not properly paired?..[JKCET 2004]
• What is true about fluid mosaic model?...[JKCET 2004]
• Besides proteins ribosomes contain :...[JKCET 2004]