Electromagnetic Signals from Bacteria

Topics: Bacteria, Magnetic field, Cell Pages: 10 (3092 words) Published: April 16, 2013


J Vindhya Vasini
III year, EIE
CVR College of Engineering
Ph. 9963857871

Mirza Faizaan Baig
III year, EIE
CVR College of Engineering
Ph. 9700484422

K Sandeep
III year, EIE
CVR College of Engineering
Ph. 9618268386

Bacteria were among the first life forms to appear on Earth, and are present in most habitats on the planet, growing in soil, water, acidic hot springs, radioactive waste, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals, providing outstanding examples of mutualism in the digestive tracts of humans, termites and cockroaches. Bacteria constitute a large domain of prokaryotic microorganisms(organisms whose cells lack a cell nucleus which contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, to form chromosomes.). Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria display a wide diversity of shapes and sizes, called morphologies. Bacterial cells are about one tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometres in length. 

Intracellular structures:
The bacterial cell is surrounded by a lipid membrane, or cell membrane, which encloses the contents of the cell and acts as a barrier to hold nutrients, proteins and other essential components of the cytoplasm within the cell. As they are prokaryotes, bacteria do not tend to have membrane-bound organelles in their cytoplasm and thus contain few large intracellular structures. The localization of proteins to specific locations within the cytoplasm have been found to show levels of complexity. These sub cellular compartments have been called "bacterial hyper structures". Extracellular structures:

Bacterial cell walls are different from the cell walls of plants and fungi, which are made of cellulose and chitin. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of Peptidoglycan(also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria , forming the cell wall.). There are broadly speaking two different types of cell wall in bacteria, called Gram-positive and Gram-negative. Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Most bacteria have the Gram-negative cell wall. Growth and reproduction:

Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced.

In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media such as agar plates are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient or with antibiotics added) can help identify specific organisms. Movement:

Many bacteria can move using a variety of mechanisms: flagella are used for swimming through water; bacterial...
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