![]() ![]() ![]() It involves two main steps:Īdd a crystal violet stain which binds to molecules in the thick peptidoglycan cell wall in gram positive bacteria turning them violet. 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. Many endospore-producing bacteria are nasty pathogens, for example Bacillus anthracis, the cause of anthrax.Bacteria are single celled organisms. This makes destroying them very difficult. These are dormant structures, which are extremely resistant to hostile physical and chemical conditions such as heat, UV radiation and disinfectants. That’s why we can quickly become ill when pathogenic microbes invade our bodies. After one more hour the number of bacteria will have risen to a colossal 16,777,216. This means that in just seven hours one bacterium can generate 2,097,152 bacteria. When conditions are favourable such as the right temperature and nutrients are available, some bacteria like Escherichia coli can divide every 20 minutes. Each daughter cell is a clone of the parent cell. The bacterial cell then elongates and splits into two daughter cells each with identical DNA to the parent cell. Binary fission begins when the DNA of the bacterium divides into two (replicates). In this process the bacterium, which is a single cell, divides into two identical daughter cells. Most bacteria reproduce by binary fission. © gaetan stoffel / iStockģD illustration of Escherichia coli How do bacteria reproduce? Relatively few bacteria are parasites or pathogens that cause disease in animals and plants. Some types cause food spoilage and crop damage but others are incredibly useful in the production of fermented foods such as yoghurt and soy sauce. Some bacteria live in the soil or on dead plant matter where they play an important role in the cycling of nutrients. A lot of these bacterial cells are found lining the digestive system. There are approximately 10 times as many bacterial cells as human cells in the human body. ![]() Some live in or on other organisms including plants and animals including humans. © ttsz / iStockīacteria are found in every habitat on Earth: soil, rock, oceans and even arctic snow. They can exist as single cells, in pairs, chains or clusters. For example it may contain a gene that makes the bacterium resistant to a certain antibiotic.īacteria are classified into five groups according to their basic shapes: spherical (cocci), rod (bacilli), spiral (spirilla), comma (vibrios) or corkscrew (spirochaetes). The plasmid often contains genes that give the bacterium some advantage over other bacteria. Some bacteria have an extra circle of genetic material called a plasmid rather than a nucleus. Their control centre, containing the genetic information, is contained in a single loop of DNA. Bacteria are microbes with a cell structure simpler than that of many other organisms. ![]()
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