Anitbiotic resistant bacteria essays

Anitbiotic resistant bacteria essays Almost 60 years ago the first antibiotics were developed, and they were created at a time when previously untreatable infections such as tuberculosis, gonorrhea, and syphilis could be almost miraculously cured. Infections like these could be a death sentence, and until recently they many be just that again. Microbes are learning the ability to fight of these antibiotics and become resistant to them. They are gaining resistance through a number of different ways, and science is in a race to keep up with there amazing evolution. Bacteria are the common name for prokaryotic cells, which lack a nucleus. Rather they have a nucleoid region where their DNA is stored in direct contact with their cytoplasm. Their DNA, through transcription and translation, directs ribosomes to assemble proteins. They reproduce by binary fission, and are mostly heterotrophic. Bacteria can exchange DNA in three ways: transformation, transduction, and conjugation. In transformation a bacterial cell becomes competent, or able to take up DNA from the surrounding fluids. In conjugation two bacterial cells, a donor and a recipient join and DNA is transferred from one to the other. In these cases the new DNA either incorporates itself into the existing DNA or forms an independent molecule within the cell called a plasmid (Christensen). Antibiotics are substances produced by microorganisms that kill or inhibit other microorganisms from growing or reproducing. Antibiotics are products of the earth and are all-natural. For clinical purposes, bacteria are said to be resistant to an antimicrobial when they are insignificantly affected by concentrations of the drug that can be achieved at the site of the infection. As might be expected, achievable concentrations vary dramatically from place to place in the body. Sensitivity of organisms to antimicrobials may be quantified by the minimum concentration required to inhibit their growth (minimum inhibitory concen...

Electrochemistry Calculations Using the Nernst Equation

Electrochemistry Calculations Using the Nernst Equation The Nernst equation is used to calculate the voltage of an electrochemical cell or to find the concentration of one of the components of the cell. The Nernst Equation The Nernst equation relates the equilibrium cell potential (also called the Nernst potential) to its concentration gradient across a membrane. An electric potential will form if there is a concentration gradient for the ion across the membrane and if selective ions channels exist so that the ion can cross the membrane. The relation is affected by temperature and whether the membrane is more permeable to one ion over others. The equation may be written: Ecell E0cell - (RT/nF)lnQ Ecell cell potential under nonstandard conditions (V)E0cell cell potential under standard conditionsR gas constant, which is 8.31 (volt-coulomb)/(mol-K)T temperature (K)n number of moles of electrons exchanged in the electrochemical reaction (mol)F Faradays constant, 96500 coulombs/molQ reaction quotient, which is the equilibrium expression with initial concentrations rather than equilibrium concentrations Sometimes it is helpful to express the Nernst equation differently: Ecell E0cell - (2.303*RT/nF)logQ at 298K, Ecell E0cell - (0.0591 V/n)log Q Nernst Equation Example A zinc electrode is submerged in an acidic 0.80 M Zn2 solution which is connected by a salt bridge to a 1.30 M Ag solution containing a silver electrode. Determine the initial voltage of the cell at 298K. Unless youve done some serious memorizing, youll need to consult the standard reduction potential table, which will give you the following information: E0red: Zn2aq 2e- → Zns -0.76 V E0red: Agaq e- → Ags 0.80 V Ecell E0cell - (0.0591 V/n)log Q Q [Zn2]/[Ag]2 The reaction proceeds spontaneously so E0 is positive. The only way for that to occur is if Zn is oxidized (0.76 V) and silver is reduced (0.80 V). Once you realize that, you can write the balanced chemical equation for the cell reaction and can calculate E0: Zns → Zn2aq 2e- and E0ox 0.76 V 2Agaq 2e- → 2Ags and E0red 0.80 V which are added together to yield: Zns 2Agaq → Zn2a 2Ags with E0 1.56 V Now, applying the Nernst equation: Q (0.80)/(1.30)2 Q (0.80)/(1.69) Q 0.47 E 1.56 V - (0.0591 / 2)log(0.47) E 1.57 V