![]() ![]() You can find populations of rock pocket mice all over the Sonoran Desert in the southwestern United States. Rock pocket mice, however, have had an enormous Grams, this tiny mouse weighs about as much as a handful of paper clips. Also embedded in text above.Name _ĬOLOR VARIATION OVER TIME IN ROCK POCKET MOUSE POPULATIONSĪ typical rock pocket mouse is about 170 millimeters long from nose to rump, shorter than an average pencil. Video about natural selection of antibiotic resistant bacteria (5 min). Mutations – selection: the bacteria resist Video from HHMI BioInteractive about a real-life example of natural selection (11 min). Natural Selection and the Rock Pocket Mouse Video that explains selection and spread of antibiotic resistance in an easy to understand manner. This animated TED-Ed video gives an overview of how antibiotics function, how bacteria evolve to resist their action and how selection of resistant bacteria works (5 min). With explanatory article.Īnimation of selection of resistant bacteria in the body, some resistance mechanisms and how they may spread. Video that visualizes the development and spread of antibiotic resistant bacteria in real time, using a giant petri dish with different concentrations of antibiotics. ![]() Narrated presentation from ReAct that describes how bacteria develop resistance and how bacteria can spread. ![]() Short video that explains natural selection of antibiotic resistance Selected ResourcesĮmergence and spread of antibiotic-resistant bacteria By using narrow-spectrum antibiotics (when possible), the risk of selecting for antibiotic resistance in the commensal flora decreases. Thus, the antibiotic can select for resistance genes and mechanisms in both pathogenic bacteria and in commensal bacteria living in the body that have nothing to do with the infection in question. When we treat an infection, selection can occur at any site in the body to which the antibiotic reaches. It is important to understand that selection of antibiotic resistant bacteria can occur anywhere an antibiotic is present at a selective concentration. The end result is a population of mainly resistant bacteria. Only the resistant bacteria will continue to proliferate in the presence of the antibiotic and increase in number over time. A bactericidal antibiotic is added, which kills most of the susceptible bacteria in the population, while the resistant bacteria survive. The starting point in this example is a large bacterial population where most bacteria are susceptible to antibiotics, but a couple of bacteria are antibiotic-resistant by chance. Natural selection of antibiotic resistant bacteria. These bacteria can now increase in numbers and the end result is a population of mainly resistant bacteria.įigure 1. If we were to treat the bacterial population with that specific antibiotic, only the resistant bacteria will be able to multiply the antibiotic selects for them. Some spontaneous mutations (or genes that have been acquired from other bacteria through horizontal gene transfer) may make the bacterium resistant to an antibiotic (See: Resistance mechanisms for information about how bacteria resist antibiotic action). Mutations are one way for bacteria to become resistant to antibiotics. ![]() Mutations can provide resistance to antibiotics If a mutation gives the bacterium an advantage in a particular environment, this bacterium will grow better than its neighbors and can increase in numbers – it is selected for. Here, Darwin’s theory of natural selection comes in. While some mutations are harmful to the bacteria, others can provide an advantage given the right circumstances. Mutations can also form due to external factors like radiation or harmful chemicals. These mutations are random and can be located anywhere in the DNA. Every time the bacterium goes through this process there is a chance (or risk, depending on the end result) that errors occur so-called mutations. Before the bacterium can divide, it needs to make two identical copies of the DNA in its chromosome one for each cell. When bacteria multiply, one cell divides into two cells. Mutationsīacteria grow and multiply fast and can reach large numbers. Resistant bacteria survive antibiotic treatment and can increase in numbers by natural selection. Mutations can result in antibiotic resistance in bacteria. ![]()
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