Bacterial Cell Structure

 

The basic components of bacterial cells are:-

• Cell wall
• Plasma membrane
• Cytoplasm
• Chromosome
• Ribosome

The outer most structure of bacteria is the cell wall a semi rigid envelope that maintains the integrity of the cell in the same way that the skin maintains the integrity of the human body.

The cell wall helps protect the cell against environmental changes for example heat, cold and drugs that would otherwise damage or destroy it.

It allows most molecules to pass through it. This layer is composed of molecules calledPeptidoglycans; this is often called Peptidoglycans layer.

Just inside the cell wall is a second less rigid envelope the plasma membrane sometimes called theinner membrane or cytoplasmic membrane which encloses the cell contents; in bacterial cells the plasma membrane has two primary functions:-

First it serves as a selective barrier to molecules that penetrating the cell wall; allowing some - such as water or oxygen - to flow easily into the cell enteria and restricting the passage of another such as proteins.

Second it contains enzymes; proteins that cause chemical reactions to occur as vital to the life functions of the cell.

Bacteria can be divided into two main groups based on differences in the cell walls structure; this difference was first noticed as differences in staining with a dye called gram’s stain.

Gram positive organisms have the structure defined so far.

But Gram negative bacteria have an additional membrane outside the peptidoglycans layer called the outer membrane; this which contains openings called channels some them formed by protein called Porins which allows nutrients, waste products, fluids to flow into and out of the cell.

Some of these channels are non-specific they allow any molecule up to certain size to flow through them; other channels are specific; only certain particular molecules can pass through them while prohibiting the entry of other molecules including antibiotic drugs into the cell; the cell wall channels protect the cell contents and enhance the likelihood of the cells of survival.

Cytoplasm is a viscid, thick, sticky substance that serves as the matrix fully interior contents of the cell; cytoplasm is made up primarily of water accounting for eighty percent of the total content; it also contains enzymes and nutrients such as carbohydrates, lipids, fats and other molecules.

In most bacteria the genetic material is contained in one single circular chromosome and contains all hereditary information required for bacteria; the chromosome consists of genes which made up ofdeoxyribonucleic acid (DNA)

DNA is a material that is composed of long and twisted strands of compounds called nucleotidesarranged in a double helix pattern; DNA Carries the codes of reproducing specific proteins which determine characteristics or functions of the organism; in the higher organisms such as humans and plants chromosomes are enclosed in the cell nucleus; therefore these organisms are calledeukaryotes; in contrast bacterial cells are prokaryotes since they lack of cell nucleus in addition to the existence of a single chromosome.

In addition to single chromosome; many bacterial cells it contains circular molecules of DNA calledplasmid; it may carry genes the codes helps for resistance to antibiotics and for production of toxins both of which are important to bacterial survival; however the DNA contained in the plasmid is not for reproduction or other of basic cell function.

There are more than one type of ribonucleic acid RNA; ribosomal RNA and other proteins complex to form the ribosome; ribosomes are structured to serve as protein factories for the cell; because the cell cannot survive without proteins; ribosomes are vital to cell life like DNA; RNA is a component of all living cells and is composed of nucleotides and arranged in long strands that unlike the double stranded DNA; RNA is a single strand of nucleic acid and the primary function of RNA is the protein synthesis; the genetic code contained in the DNA is transcribed into messenger RNA which then travels to the ribosomes;  the genetic code is then translated into proteins.