MORPHOLOGY AND STRUCTURE OF BACTERIA

Bacteria are essential to human life as they play a nutritious role, causing disease and helping to convert environmental nitrogen to Nitrate. Cyanobacteria and Rhizobium are Nitrogen Fixing bacteria that help in fixing nitrogen. As nitrogen is a part of amino acids or protein it is essential for human life. Bacteria are prokaryotic cells that lack nuclei and membrane-bound organelles. They composed a Single circular DNA consisting of Chromosomes. Bacteria helps in fermentation of curd, bread and wines as they have an extreme industrial value. They help in digestion in the Ruminant stomach in cattle such as cows, goats and sheep to digest cellulose.  

Morphology and Structure of bacteria

Bacteria are complex and heavily variable structures; they have different shapes and structures as spherical, rod-shaped, arc-based and spiral. Bacteria cells are very small and simple but they have diverse structures and morphology according to their habit and metabolism. A bacterium is an uninuclear prokaryotic cell that lacks a membrane-bound to its nucleus. Unit for measuring size of bacteria is micrometer average ranges of bacteria ranges from 0.5 to 5 ㎛. Size in bacteria plays a significant role in their survival. Most bacteria possess a rigid cell shape that provides structure and protection from the external environment in unfavorable conditions. Shapes and structures of bacteria help them to cope and adapt to external conditions. Cocci is a spherical-shaped bacterium, also called oval-shaped bacteria. These bacteria can live in solitary or in attached forms and often make colonies that are cosmopolitan in nature. Bacilli are Rod-shaped Bacteria, these are the oldest bacteria on earth, they are similar in Behavior with E.Coli with chemotactic movement. Cocci bacteria live in chains and clusters and remain attached during cell division or reproduction. 

Structure of bacteria

Outer layer of the cell envelope of bacteria consists of two components: first is the cell wall and beneath it is the plasma membrane of the cell membrane. Cell wall is rigid and helps to give shape to the bacteria and also prevents cells from expanding and swelling due to water uptake. Cell walls consist of proteins that help bacteria for growth and division. An outer membrane in Gram-negative bacteria functions as a barrier for the external environment and is composed of Lipopolysaccharides or LPS. Cytoplasmic membrane is present just beneath the rigid cell wall found in both gram-positive and gram-negative bacteria; a thin layer is present that separates cell wall from cell membrane in Bacteria. Cytoplasm is surrounded by cell membranes that consist of important organelles such as Ribosomes, Mitochondria, Golgi bodies, Endoplasmic Reticulum and Chromosome. DNA in bacteria is haploid (consist of a number of chromosomes) and circular in structures also consist of plasmids; they are extra circular DNA.

Ribosomes in bacterial cells are smaller than ribosomes of Eukaryotic cells. Mesosomes are tubular forms formed by invagination of cell membranes; they are the principal site for respiratory enzymes and also help in reproduction of bacteria. A nucleus in bacterial cells lacks a nuclear membrane and nucleus. Nucleus of Bacteria does not contain DNA unlike Eukaryotic cells thus lacking genetic materials. Cytoplasm carries genetic information in bacterial cells. Capsule is the outermost layer of bacteria that protects against complements and is antiphagocytic in nature.  Flagellates are an extending cytoplasm originating from axoneme that provides motility and is known as a locomotory organ of bacteria. Monotrichous are known as single flagellated bacteria. 

Structure of Bacterial cell

Composition of cell walls of bacteria varies among different bacteria and cytoplasm or protoplasm of bacteria cells help in growth, metabolism and replication. Gel-matrix of the cell membrane is composed of water, nutrition and enzymes. Cytoplasmic membrane is a protein-lipid structure. Cell membrane composed of phospholipids with hydrophilic heads and hydrophobic tails. Heads of these phospholipids are arranged towards the outside and inside as there is water and tails are arranged towards the inner side as they are hydrophobic. That regulates flow of materials inside and outside of the cell. Structure of bacteria is composed of living cells that act as a barrier that allows them to selectively interact with the environment. Many species of bacteria consist of Pili which are hairlike projections that help to attach with other cells. 

Morphology meaning in Biology

Morphology is defined as an external structure of an organism that includes size, shape, measurement and Color. Morphology is a term that means “study of forms or things”. It helps to identify an organism from outside such as shape of bacteria, size, color and measurement of bacteria. 

Conclusion

Bacteria are single-celled organisms, microscopic organisms consisting of prokaryotic cells. They possess rigid cell walls that protect them from unfavorable external conditions such as extreme hot or cold. They have different morphological structures dependent upon their ability to cope with external environments. Due to their different structure and morphology, identification of bacteria is tough. They have genetic material DNA which is circular and situated in cytoplasm rather than in Nucleus. They have naked nuclei without a nuclear membrane. Bacteria have an important role in nitrogen fixation and fermentation of dairy products.