Evolution and Antibiotic Resistance

"Evolution and Antibiotic Resistance"

March 7, 2012

Biology I

Instructor Raven

Shantel Peiffer

South University Online

For this assignment I have chosen to give definitions of both evolution and antibiotic resistance and write about them. Most of my paper may be taken from text, with correct citations in place, but I feel that being done this way I am representing facts and not giving my opinion or "theory" on these subjects.

Evolution is the change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift. (Retrieved from dictionary.com) The term evolution is simply: "Descent of a population with some modification." One misconception is that "an individual evolves", when actually a single organism may gain a new characteristic, but in order for evolution to occur that characteristic has to be passed on to successive generations and integrated into the population. (Week 2: Readings and Assignments. Online lecture: The Principles of Evolution I (1 of 6). In studying evolution at the population level, biologists focus on the gene pool, the total collection of alleles The ancestors of all life, the prokaryote, is the oldest known fossil, dating from about 3.5 billion years ago. (Simon et al. 2010 p. 3).

in a population at any one time. (Simon et al. 2010 p. 19). A nonevolving population is in genetic equilibrium, or Hardy-Weinburg equilibrium. (Simon et al. 2010 p. 24).

Genetic drift, gene flow, and mutations can cause evolutionary change, but don't always lead to adaptation. (Week 2: Readings and Assignments. Online lecture: The Principles of Evolution I (4 of 6). There are two types of genetic drifts, the bottleneck effect and the founder effect. (Simon et al. 2010 pp. 26-28). Through the process of natural selection, species can become highly adapted to their environments. (Simon et al. 2010 p. 1).

Antibiotic resistance is the ability of bacteria or other microbes to resist the effects of an antibiotic. The development of antibiotic and pesticide resistance is often presented as a modern example of evolution by mutations and as clear evidence for Darwinism. Many Darwinists have claimed that the development of antibiotic-resistance is one of the strongest evidences of Darwinian evolution. There is a common claim that the development of resistance to antibiotics provides evidence for the molecules-to-man evolution theory is based at its foundation on mutations.

Non-resistant bacteria commonly become resistant by several different means, most of which have nothing to do with mutations. Palumbi notes that in 'most cases' antibiotic resistance results from selection of an existing genetic trait, especially those traits that are highly variable, such as the natural defences that all organisms possess. (Palumbi, S.R., Evolution--humans as the world's greatest evolutionary force, Science 293:1786-1790, 2001; p. 1787.) An important mechanism by which bacteria become resistant is by obtaining one or more specific resistance genes from other bacteria. This type of resistance can be obtained by the transfer of a plasmid (small circular units of DNA), already existing in the bacterium gene pool, that carries a gene for an enzyme which either destroys or inactivates the antimicrobial substance. (Burton, G. and Engelkirk, R, Microbiology for the Health Sciences, Lippincott Williams and Wilkins, Philadelphia, pp. 199-201, 2000.) Many resistance genes are also carried on self-transmissible genes known as transposable elements, that can jump between plasmids and chromosomes. (Walkup, L., Junk DNA, Journal of Creation. 14(2):18-30, 2000.)

Antibiotics are produced naturally by fungi and bacteria which have coexisted since Creation as part of their own defence systems. Without innate defences, bacteria could not protect themselves and would soon become extinct. When an antibiotic reaches the bacterial periplasm or cytoplasm it may be inactivated by modification, isolation, or destruction, all of which are due not to mutations', but rather to complex, innate, physiological mechanisms. When a bacterial strain has gained resistance to an antibiotics, it is more correct to say that the bacteria it has lost sensitivity to the antibiotic. Bacteria have had resistance to many antibiotics long before humans used them. This has been confirmed by culturing bacteria found on human explorers frozen to death long before human-developed