Question

Write an essay about bacteria (400 word). Use your own words. Essay should continue introduction, body (3 paragraphs),and conclusion.

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Answer 1

Bacteria are the unicellular /prokaryotic organism. They vary in size ranging from 0.5 to 2 µ. The structure of bacterial cell is very simple, there is no nucleus or membrane bound organelles such as golgi bodies, mitochondria, endoplasmic reticulum in the cell. They have a single circle of DNA and very few bacterias have an extra genetic material called as plasmid. Plasmid contains genes which has certain advantages over other bacteria. They reproduce by binary fission and it is also evident that sexual reproduction takes place by exchange of genetic material by 3 modes of transmission such as conjugation, transformation and transduction.

Structure:

The ultra structure of bacteria is seen under the electron microscope which is noted for years. The bacterial cell contains 2 compartments 1) Outer cell wall covering 2) Inner cell body. The outer cell wall is made of 3 layers such as a) capsule or slime layer, b) cell wall and c) cell membrane. a) The slime layer forms the capsule or sheath. Generally the capsule is made up of polysaccharides in rare occasion’s polypeptides. The slime layer is very important in terms of protecting the bacteria from unfavorable conditions. The layer also has a vital role is causing disease to animals and humans. The capsule or the slime layer is followed by cell wall also called the protective layer (protects the cytoplasm) of the bacterial cell which majorly differentiate a bacteria as gram positive and gram negative. b) The presence of the cell wall depends on environmental factors. It is a strong and rigid (due to presences of mcucopeptide) part of the cell which is granular and porous. Cell wall contains, carbohydrates, lipids, phosphorous, proteins, inorganic substances and aminoacids such as alanine, glycine etc. c) The third component is cell membrane or cytoplasmic membrane that lies beneath the inner surface of cell wall. It contains lipids and proteins arranged in mosaic model composed of phospholipids. The phospholipid can be are hydrophilic (affinity towards water/ mix with water) and hydrophobic (repel from water/do not mix with water). The cell membrane has many infoldings called mesosomes (key player in DNA replication and cell division). 2) Inner cell body or protoplasm consists of a) cytoplasm and b) nucleoplasm. a) Cytoplasm is present between plasma membrane and nuclear region filled with granular cytoplasm. It is a mixer of proteins, lipids minerals including water. It contains the oraganells (ribosomes, mesosomes, ribonucleic acid, chromatophores , nucleoplasm) and inclusions such as (volutin storage granules, glycogen, lipids and globules). b) Nucleoplasm which is always a debate in this place the genetic material is concentrated. It looks like a rudiment were it does not have nucleolus, nuclear membrane etc and divide by a process called amitosis (A cell division without spindle fibres formation and chromosomes appearance). Therefore, the bacterial nuclear region is termed as nucleoid.

Classification:

It is classified mainly based on 6 important factors their shape, cell wall type, nutrition uptake, cell appendages/flagella, temperature in which they are living and the oxygen requirement (Fig 1).

Merits and demerits of bacteria

Till now there are more than 2500 species are identified, but the usefulness of the same is still a debate. Though many microbes (bacteria) have a great role in causing disease they play a major role for the benefits of other living organism. Merits of having bacteria is well appreciated in agriculture by decomposition process (eg: saprophytic bacteria such as Bacillus vulgaris are called the scavengers which decompose the waste), industries (dairy, leather, textile) Eg: Food fermentation process eg: cheese, pickles, wine etc) and soil fertility by increasing the fertility of the soil Eg: nitrifying bacteria: Nitrobacter. Used for medicinal purpose such as antibiotics (many antibiotics are obtained from bacteria Eg Streptomycin from Streptomyces griseus) also in production of vaccines against many diseases. Few bacteria used to synthesis vitamins, pest control etc. There are always a good and a bad in this way the demerits of bacteria are causing food poisoning or producing toxins. Eg botulism by Clostridium botulinum, De-nitrification in the soil, causing pollution in water which is the main concern in many developing countries Eg: Salmonella typhi contaminating the drinking water and also these bacteria can be used as warfare agents Eg: anthrax. By studying the merits and demerits scientists and the researchers perform the latest technologies such as genetic engineering to improve the quality of life by using these single cell organism (bacteria) to introduce the commercial viable products such as hormones, insulin, enzymes to the world.