Classification of Cells - Plant, Animal and Bacterial Cells
A Cell is the basic structural and functional unit of organisms. The word ‘cell’ is derived from the Latin word “cella” which means “small room”. The type and number of cells in plants and animals vary. The cells can be classified in different ways. For example, based on the presence of a nuclear membrane, the cells are classified into two types i.e Eukaryotic and prokaryotic. Cells may also be classified based on the number of cells an organism is made of i.e unicellular, multicellular, and acellular.
Brief on Animal Cell
An animal cell is typically a eukaryotic type that has a well-defined nucleus and other membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. All cells are surrounded by a cell membrane or plasma membrane which separates the inner and outer components of the cell. The cell components are suspended in a fluid called cytoplasm.
Animals are multicellular organisms. The cells are specialized to perform various functions. Also, they look and function differently from each other even if they belong to the same organism.
Animal Cell Types
There are numerous types of animal cells and each of them is designed to serve specific functions. However, some of the most common types of animal cells are as follows:
Skin Cells
Melanocytes, keratinocytes, Merkel cells and Langerhans cells
Muscle Cells
Myocyte, Myosatellite cells, Tendon cells, Cardiac muscle cells
Blood Cells
Leukocytes, erythrocytes, platelet
Nerve Cells
Schwann cell, glial cells etc
Fat Cells
Adipocytes
Animal cells need to adapt to a more active and non-sedentary lifestyle as animals acquire their food, hence, they do not possess any of the specialized cell organelles such as chloroplasts.
Brief on Plant Cell
A plant cell is mainly a eukaryotic cell with a true nucleus and organelles similar to an animal cell but also consists of certain specific components such as chloroplasts which carry out photosynthesis. Plants are multicellular and have a distinct rigid wall surrounding the cells.
Plant Cell Functions
The plant cells are the building blocks of the plants. Since photosynthesis (the process of preparing food by the plants, by utilizing sunlight, carbon dioxide and water) is the major function performed by the plant cells it occurs in the chloroplasts of the plant cell.
Plant Cell Types
There are different types of plant cells some of which include the following different types:
Collenchyma Cells
These cells are hard or rigid and play a primary role in providing support to the plants if there is restraining growth due to the lack of hardening agents in the primary walls.
Sclerenchyma Cells
These are more rigid as compared to the collenchyma cells and it is because of the presence of a hardening agent. They are usually found in all the plant roots and are mainly involved in providing support to the plants.
Parenchyma Cells
The Parenchyma cells have a significant role to play in all plants. As they are the living cells of plants, which are involved in the production of leaves, they are also involved in the exchange of gasses, production of food, storage of organic products and cell metabolism. The Parenchyma cells are typically more flexible because they are thinner than other cells.
Xylem Cells
The Xylem cells are the transport cells in vascular plants. They are responsible for the transport of water and minerals from the roots to the leaves and other parts of the plants.
Phloem Cells
These are the common type of cells and the most heard ones, the phloem cells are the transport cells in vascular plants as they are responsible for transporting food which is prepared by the leaves to different parts of the plants.
Brief on Bacterial Cell
A bacterial cell is a prokaryotic cell that lacks a well-defined nucleus and membrane-bound organelles. Instead, it contains an irregular-shaped region where the genetic material is suspended. Bacteria is a single-celled organism.
Functions of a Bacterial Cell
The Cytoplasm or protoplasm is the part of the bacterial cells, where the functions for cell growth, metabolism, and replication are carried out. This is a gel-like matrix that is composed of water, enzymes, nutrients, wastes, and gasses and contains cell structures such as ribosomes, a chromosome, and plasmids.
Types of Bacteria Cells
The Bacterial cells are classified into five groups according to their basic shapes:
Spherical (cocci)
Rod (bacilli)
Spiral (spirilla)
Comma (vibrios)
Corkscrew (spirochaetes)
These can exist as single cells, in pairs, chains or clusters.
Difference Between Plant, Animal and Bacterial Cell
Conclusion
Having a brief knowledge about different bacterial cells will certainly help you in learning deeper and understanding it.
FAQs on Difference Between Plant, Animal and Bacterial Cells
1. What are the main differences between plant, animal, and bacterial cells?
The main differences are based on their internal structure and complexity. Plant and animal cells are eukaryotic, meaning they have a true, membrane-bound nucleus and specialized organelles. In contrast, bacterial cells are prokaryotic, which are simpler and lack a nucleus. Key differences also include the presence of a cell wall in plants and bacteria but not in animals, and the presence of chloroplasts for photosynthesis only in plant cells.
2. What key structures are found in plant and animal cells but are absent in bacterial cells?
Plant and animal cells contain several complex structures called organelles that are not found in simpler bacterial cells. The most important of these are:
- A true nucleus, which houses the cell's DNA.
- Mitochondria, responsible for generating energy through respiration.
- The endoplasmic reticulum and Golgi apparatus for processing and transporting proteins.
- Lysosomes and peroxisomes for breaking down waste.
Bacterial cells lack all of these membrane-enclosed structures.
3. How does having a cell wall affect a cell's function and shape?
A cell wall provides critical structural support and protection. In plant cells, the rigid wall made of cellulose helps the plant maintain a fixed shape and withstand pressure. In bacteria, a wall made of peptidoglycan prevents the cell from bursting. Animal cells lack a cell wall entirely, which allows for greater flexibility and movement, essential for functions like muscle contraction and cell migration.
4. How do plant, animal, and bacterial cells differ in the way they get energy?
They use very different strategies for energy production, which defines their role in an ecosystem.
- Plant cells create their own food. They use chloroplasts for photosynthesis to convert light into chemical energy (glucose) and also have mitochondria to break it down for power.
- Animal cells must consume food. They use mitochondria to perform cellular respiration, converting glucose from food into usable energy (ATP).
- Bacterial cells are highly diverse. Some perform photosynthesis, others use respiration, and many can get energy through processes like fermentation or even by breaking down inorganic chemicals.
5. Why is the genetic material in a bacterial cell not enclosed in a nucleus?
This is the fundamental difference between prokaryotes (bacteria) and eukaryotes (plants, animals). In plant and animal cells, the nucleus acts as a protective compartment, keeping the DNA organised and safe. Bacterial cells lack this compartment. Their genetic material, a single circular chromosome, floats in a dense part of the cytoplasm called the nucleoid region. This simpler design allows bacteria to grow and reproduce much more quickly than eukaryotic cells.
6. Despite their differences, what important similarities do plant and animal cells share?
Yes, because they are both eukaryotic cells, plant and animal cells share several complex features not found in bacteria. Both have:
- A cell membrane that regulates what enters and exits the cell.
- A true nucleus containing the cell's DNA.
- Cytoplasm where organelles are suspended.
- Ribosomes to build proteins.
- Mitochondria to generate energy from glucose.
7. Do any structures inside plant and animal cells resemble bacteria?
Yes, this fascinating observation supports a major biological theory. The organelles mitochondria (in both plant and animal cells) and chloroplasts (in plant cells) are strikingly similar to bacteria. They are about the same size, have their own circular DNA, and reproduce independently inside the cell. The Endosymbiotic Theory proposes that these organelles were once free-living bacteria that were engulfed by a larger cell, forming a partnership that has lasted billions of years.
