Structure of prokaryotic and eukaryotic cell

Structure of prokaryotic and eukaryotic cell

Structure Eukaryotic Cell

Eukaryotic cells have nuclei enclosed within a nucleus and form larger and more complex organisms. Protozoa, fungi, plants, and animals all have eukaryotic cells. They were divided under the Eukaryota empire.

They can store different areas in a single cell that allows them to perform different metabolic reactions. This helps them grow many times larger than prokaryotic cells.

Characteristics of Eukaryotic cells

The characteristics of eukaryotic cells are as follows:

• Eukaryotic cells have a nucleus trapped inside a nuclear membrane.
• The cell has mitochondria.
• Flagella and cilia are the moving organs in the eukaryotic cell.
• The cell wall is the outer layer of eukaryotic cells.
• Cells divide by a process called mitosis.
• Eukaryotic cells contain a cytoskeletal structure.
• The nucleus contains a single strand of DNA, which carries all the genetic information.

Eukaryotic Cell Structure

The structure eukaryotic cell includes the following:

Plasma Membrane

• The plasma membrane separates the cell from the outer surface.
• It contains a number of embedded proteins, which aid in the exchange of substances within and outside the cell.

The Cell Wall

• The cell wall is a solid structure that exists outside the plant cell. However, it is not present in animal cells.
• It provides the cell structure and assists cell-cell interaction.
• It is a protective layer that protects the cell from any damage or attack by a pathogen.
• It is made up of cellulose, hemicellulose, pectin, protein, etc.

Cytoskeleton

The cytoskeleton exists within the cytoplasm, which contains microfilaments, microtubules, and fibres to provide the complete cell structure, stabilise organelles, and stimulate cell movement.

Endoplasmic Reticulum

It is a network of small, tubular structures that divide the cell surface into two parts: luminal and extraluminal.

Endoplasmic Reticulum of two types:

• The Rough Endoplasmic Reticulum contains ribosomes.
• The Smooth Endoplasmic Reticulum has no ribosomes so it is smooth.

The nucleus

• The nucleoplasm enclosed within the nucleus contains DNA and proteins.
• The nuclear envelope has two layers – the outer layer and the inner layer. Both membranes are able to penetrate ions, molecules, and RNA substances.
• Ribosome production also occurs within the nucleus.

Golgi Apparatus

• It is made up of flat disc-shaped structures called cisternae.
• It is not present in human red blood cells and plant filter cells.
• They are organised and centred around the nucleus.
• It is an important source of glycoproteins and glycolipids.

Ribosomes

These are the major sources of protein synthesis and are made up of proteins and ribonucleic acids.

Mitochondria

• These are also known as “energy cells” because they produce energy.
• It contains the outer layer as well as the inner membrane. The inner membrane is divided into bars called cristae.
• They help regulate cell metabolism.

Lysosomes

They are known as “suicide bags” because they contain hydrolytic enzymes that break down proteins, lipids, carbohydrates, and nucleic acids.

Plastids

These are two-organ structures and are only found in plant cells. There are three types:

• Chloroplast contains chlorophyll and is involved in photosynthesis.
• Chromoplast contains a pigment called carotene that gives plants yellow, red, or orange colours.
• Leucoplasts are colourless and store oil, fats, carbohydrates, or proteins.

Eukaryotic Cell Cycle

Eukaryotic cells divide during the cell cycle. The cell goes through different stages during the cycle. There are different checkpoints between each stage.

Quiescence (G0)

This is known as the resting phase, and the cell does not split during this phase. The cell cycle begins at this stage. Cells from the liver, kidneys, neurons, and stomach all reach this stage and can remain there for a long time. Most cells do not enter this phase and separate permanently during their lifetime.

Interphase

At this stage, cells grow and absorb nutrients to prepare for division. It contains three

checkpoints:

• Gap 1 (G1) – Here the cell grows. Protein is also increasing.
• Synthesis (S) – DNA replication occurs at this stage.
• Gap 2 (G2) – Cells grow to be mitotic.

Mitosis

Mitosis includes the following stages:

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

In the division, each cell of the daughter is exactly the same as the original cell.

Examples of Eukaryotic cells

Eukaryotic cells are found only in plants, animals, skins, protozoa, and other complex organisms. Examples of eukaryotic cells are listed below:

• Plant Cells: The cell wall is made of cellulose, which provides support to the plant. It has a large vacuole that retains turgor intensity. The plant cell contains chloroplast, which aids in the process of photosynthesis.
• Fungus cells: The cell wall is made of chitin. Some fungi have holes called septa that allow organelles and the cytoplasm to pass through them.
• Animal Cells: These do not have cell walls. Instead, they have a cell membrane. That is why animals come in many forms. They have the potential to cause phagocytosis and pinocytosis.
• Protozoa: Protozoans are unicellular organisms. Some protozoa have movement cilia. A thin layer called the pellicle provides cell support.

Prokaryotic Cell and its structure

Prokaryotic cells are single-celled microorganisms known as the world’s first. Prokaryotes include Bacteria and Archaea. Photosynthetic prokaryotes include cyanobacteria that produce photosynthesis.

The prokaryotic cell contains a single cell and therefore, all reactions occur within the cytoplasm. They can be free-living or parasites.

Features of Prokaryotic Cell

Prokaryotic cells have different characteristics. The characteristics of prokaryotic cells are listed below.

• They lack a nuclear membrane.
• Mitochondria, Golgi bodies, chloroplasts, and lysosomes are absent.
• The genes are present in a single chromosome.
• Protein histone, an essential component of eukaryotic chromosomes, is deficient in it.
• The cell wall is made up of carbohydrates and amino acids.
• The plasma membrane acts as a mitochondrial membrane that carries respiratory enzymes.
• They divide the sex into two separate divisions. The sexual reproductive system involves intercourse.

Prokaryotic Cell Structure

The prokaryotic cell does not have a nuclear membrane. However, genes exist locally in the cytoplasm known as nucleoid. They may be round, rod-shaped, or round. The structure of the prokaryotic cell is as follows:

• Capsule – An external protection found in bacterial cells, above the cell wall. It helps to retain moisture, protects the cell when it is trapped and helps to adhere to nutrient cells and surface surfaces.
• Cell Wall- The outer layer of a cell that makes a cell stand out.
• Cytoplasm- Cytoplasm is made up mainly of enzymes, salts, cell organelles and is a gel-like substance.
• Cell Membrane- This layer surrounds the cytoplasm and regulates the entry and exit of material from cells.
• Pili- These are hairy leaves that attach more to other germ cells.
• Flagella- These are long structures in the form of a whip, which aid in the movement of the cell.
• Ribosomes – These are involved in the synthesis of proteins.
• Plasmids – Plasmids are non-chromosomal DNA structures. These are not involved in reproduction.
• Nucleoid Region – A region in the cytoplasm where genes are present.
• The prokaryotic cell lacks certain organisms, such as the mitochondria, the endoplasmic reticulum, and the Golgi body.

Parts of Prokaryotic Cells

Prokaryotic cells have four main components:

• Plasma Membrane- It is external protection of the phospholipid molecule that separates the cell in the environment.
• Cytoplasm – A gel-like substance inside a cell. All cell organelles are suspended in them.
• DNA – The cell gene. All prokaryotes have round DNA. It regulates what proteins are produced by the cell. It also controls cell actions.
• Ribosomes- Protein synthesis occurs here.

Some prokaryotic structure cells have cilia and flagella that help to break out.

Reproduction in Prokaryotes cell

Prokaryote produces in two ways:

• Asexually by binary fission
• Sex in combination

Binary Fission

The DNA of living organisms replicates and new copies are attached to the cell membrane.

• The cell wall begins to expand in size and begins to move inward.
• A cell wall is then built between each DNA, dividing the cell into two female cells.

Reassembling

In this process, genes from a single bacterium are transferred to the genome of other viruses.

It occurs in three forms — conjugation, conversion, transduction.

• Integration is the process by which genes are transferred between two cells in the form of a protein tube called a pilus.
• The mutation is the process by which a number of DNA strands in an environment are absorbed by a bacterial cell and inserted into its DNA.
• Transformation is the process by which genes are transferred to a bacterial cell with the help of bacteria. Bacteriophages are a virus that starts the process.

Examples of Prokaryotic cells

Examples of prokaryotic cells and structure are listed below:

Bacterial Cells

• These are living things that are found everywhere on earth from the ground to the human body.
• They have different shapes and structures.
• The cell wall is made up of peptidoglycan which provides structure in the cell wall.
• Bacteria have different properties such as pili, flagella and capsule.
• They also have extrachromosomal DNA known as plasmids.
• They have the ability to form strong, stable structures known as endospores that help them survive under adverse conditions. Endospores begin to function when conditions favour.

Archaeal Cells

• Archaebacteria are unicellular organisms similar to bacteria in shape and size.
• They are found in the worst places such as hot springs and other places like soils, swamps, and even within people.
• They have a cell wall and flagella. The cell wall of archaea does not contain peptidoglycan.
• The archaea membrane contains different lipids with completely different stereochemistry.
• Like viruses, archaea have a single circular chromosome. And they have plasmids.

Prokaryotic cells, in particular, have four main components:

• Plasma Membrane- The Plasma Membrane is the outer protective layer of phospholipid molecules that separate the cell from the surrounding environment.
• Cytoplasm- Cytoplasm is a gel-like substance inside a cell and all the organelles of cells are embedded in it.
• DNA- DNA is the genetic component of a cell. All prokaryotes have around DNA and regulate which proteins are produced by the cell and regulate cell actions.
• Ribosomes – Ribosomes are responsible for the formation of proteins.

Some examples of Eukaryotic Cells

• Eukaryotic cells: Cells are found in plants, animals, fungi, protozoa, and other complex organisms. Some examples of eukaryotic cells are:
• Plant Cells: The cell wall is made up mainly of cellulose which provides support for the plant and has a large vacuole that maintains turgor pressure. The plant cell contains chloroplast, which aids in the process of photosynthesis.
• Fungus cells: The cell wall of the fungal cells is made up of chitin. Some fungal cells have holes called septa that allow organelles and the cytoplasm to pass through them.
• Animal Cells: Animal cells do not have cell walls but have cell membranes and this is the reason why animals have so many different shapes and abilities to cause phagocytosis and pinocytosis.
• Protozoans: Protozoans are known as unicellular organisms. Even some protozoa have movement cilia. A thin layer of protozoa called the pellicle provides cell support.

FAQs

What is a Prokaryotic cell?

A prokaryotic cell is an old type of cell characterised by the absence of a nucleus. In addition, prokaryotes do not have cellular organelle bound to the membrane. Prokaryotes are not only unicellular.

What is a Eukaryotic cell?

Eukaryotic cells are cells that have a real nucleus and organelles bound to the membrane. Eukaryotes can be unicellular or multicellular.

What is the difference between a Prokaryotic and a Eukaryotic cell?

A descriptive feature that distinguishes between a prokaryotic cell and a eukaryotic nucleus. In prokaryotic cells, the true nucleus is absent, in addition, membrane-bound organelles are present only in eukaryotic cells. Another major difference between prokaryotic and eukaryotic cells is that prokaryotic cells are only unicellular, while the same does not apply to eukaryotic cells.