Evolution: How does antibiotic resistance in bacteria demonstrate various princi

Question

Evolution:

How does antibiotic resistance in bacteria demonstrate various principles of evolution, including selection, fitness, mutation, adaptation, bottlenecks and alleles? Be sure to underline each of these terms where you explain them in your paragraph.

Where do antibiotics come from? How is this source related to evolution?

What is population diversity, and how is it related to evolution? Why is genetic diversity (genetic variability) critical for evolution to occur? What would happen to a population or a species if it did not have any genetic diversity?

List several ways that a prokaryotic population can become more genetically diverse. What other ways can eukaryotes gain genetic diversity?

Explanation / Answer

* Organisms evolve to develop antibiotic resistance. In true sense, nature puts selective pressure, resistant organisms that exist in the population are selected by the nature, and further evolution of these organisms occur

* Mutations leads to development of antibiotic resistance, either by modifying a receptor that an antibiotic binds, or by modifying an enzyme that results in overcoming the inhibitory effect exerted by the antibiotic

* Adaptation: Antibiotic resistance is an adaptation to survive in the presence of an antibiotic. Bacteria that are constantly exposed to sub-inhibitory levels of an antibiotic develop a temporary resistance to it. It is called epigenetic adaptation.

* For an antibiotic resistant bacterium, lack of antibiotic means a reduction in fitness

* Antibiotics are secondary metabolites synthesized by certain bacteria/actinomyces to compete with other bacterial strains in natural environment

* Population diversity is the variation in genetic and morphological features that define the different populations. Evolution gives rise to population diversity. This occurs through speciation, anagenesis, and extinction. Genetic diversity helps organisms to evolve in different environmental conditions, adapt and evolve to changing environments. The more is the variation, the more are the number of alleles existing in the population that suit the environment. Lack of genetic diversity leads to fast extinction of the population. For example, if all the population have a single allele for a specific protein, and if a pathogen attacks that protein, all the representative organisms are wahsed out, and the entire population will be extinct.

* Prokaryotic population can become more genetically diverse through the mechanisms of * Mutation * Recombination through conjugation, transduction, and transformation

* Eukaryotes gain genetic diversity through sexual reproduction - recombination, mutation, gene amplication

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