![]() PABA is then converted to DHFA which is converted inside the cell to THFA then folic acid.Ī gram stain is used as a quick way to check a sample under the microscope to look for bacteria. This chain starts with PABA, which is directly absorbed in to the cell across the cell membrane. Folic acid cannot be created or directly imported into the cell and requires a chain of intermediates to get in to the cell. Ribosomes are where bacteria proteins are synthesised within the bacterial cell.įolic acid is essential for synthesis and regulation of DNA within the bacteria. Nucleic acid is essential component of bacterial DNA. The cell wall is a structure that surrounds the outer cell membrane and is found on gram positive bacteria. There are some key components to learn about as they are the target of antibiotic treatment: Rod shaped bacteria are called bacilli and circular shaped bacteria are called cocci. Atypical bacteria cannot be stained or cultured in the normal way.īacteria can also be classified based on their shapes. Gram negative bacteria don’t have this thick peptidoglycan cell wall and don’t stain with crystal violet stain but will stain with other stains. Gram positive bacteria have a thick peptidoglycan cell wall that stains with crystal violet stain. Learning where bacteria fall within these categories helps you work out which antibiotics will be effective against them.Īerobic bacteria require oxygen whereas anaerobic bacteria do not. They can be categorised into aerobic and anaerobic, gram positive and gram negative and atypical bacteria. These pathogenic bacteria are the most relevant to learning medicine. Most bacteria are not harmful however some are pathogenic and cause infectious diseases. ![]() Both unfinished antibiotic courses and overuse of antibiotics have also led to increased instances of antibiotic resistant bacteria.Bacteria are single celled organisms. It is important to finish all the antibiotics that are prescribed, so that the immune system doesn’t have to work as hard to fight the infection. Bacteria resistant to the effects of the antibiotic remain, but in small numbers they can be eliminated from the body by the immune system. Penicillin kills most of the bacterial cells, but it does not kill them all. Viruses are unaffected by antibiotics because they do not have peptidoglycan cell walls or ribosomes, and they do not replicate their own DNA.īacteria can become resistant to antibiotics through the process of selection and evolution. Ciprofloxacin, one of the strongest antibiotics, attacks bacterial DNA replication while leaving human cellular DNA unaffected.Īntibiotics are highly specific to a certain bacterial function, and are not helpful for treating non-bacterial illnesses. Tetracycline antibiotics bind to bacterial ribosomes that are responsible for protein production and inhibit bacterial protein synthesis. Sulfa antibiotics target a specific enzyme that inhibits bacterial growth. Other antibiotics target different molecules that inhibit bacterial growth while leaving human cells undamaged. Image courtesy of Graevemoore, Wikimedia Commons Human cells do not contain peptidoglycan, so penicillin specifically targets bacterial cells. The cells burst open and are much easier for the immune system to break down, which helps the sick person heal more quickly. Penicillin works best on gram-positive bacteria by inhibiting peptidoglycan production, making the cells leaky and fragile. Gram-negative bacteria have peptidoglycan between membranes. Gram-positive bacteria have a peptidoglycan layer on the outside of the cell wall. Within bacteria, there are two types of bacterial cell walls. Composition of the cell wall in the archaea is more diverse. The cell walls of most fungi are made from chitin. Algae cell walls can be made of cellulose, xylan, silica, carrageenan or a variety of other materials. The cell walls of algae are highly variable. ![]() The cell walls of plants, for example, are made from cellulose. The composition of the cell wall differs depending on the type of organism, so penicillin does not affect other organisms. Nearly every bacterium has a peptidoglycan cell wall. Peptidoglycan molecules form strong links that give the bacterial cell strength as well as preventing leakage from the cytoplasm. Penicillin interferes with the production of a molecule called peptidoglycan. When used as an antibiotic treatment, penicillin operates by a very specific mechanism. Penicillin was first used to treat bacterial infections in 1942 and is derived from the fungus Penicillium sp. ![]() Modern physicians frequently prescribe antibiotic medications to help people fight infections. One of the first antibiotics discovered was penicillin.
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