• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Antibiotics and Penicillin.

Extracts from this document...


Antibiotics: Penicillin Introduction Antibiotics belong to a group of chemical substances referred to as secondary metabolites. Antibiotics inhibit the growth of, or kill, bacteria. The first naturally-occurring antibiotic and the first to be used therapeutically was penicillin. It was first discovered by Alexander Fleming in 1929 almost by accident. He was growing plates of pathogenic bacteria and noticed that, when they were contaminated with the mould Penicillium notatum, growth of the bacteria was inhibited. Penicillin was isolated from the medium and found to be responsible for the effect. Since the 1940's, Penicillin and other antibiotics of fungal origin have produced a revolution in the history of medicine to the extent that many major infectious diseases have largely been brought under control. ............ As previously mentioned in the introduction, antibiotics belong to a group of chemical substances referred to as secondary metabolites. Secondary metabolites are substances (e.g. penicillin) that are by-products of processes that are not essential to life, but which have a useful role. Penicillin is an antibiotic made to kill off competitors when nutrients are scarce. The rate of production of a secondary metabolite is fastest during stationary phase when nutrients are beginning to run out. ...read more.


induce Penicillium chrysogenum to make lots of penicillin by limiting the amount of food available within the fermenter where the mould is growing. The genes inside the fungal cells don't know that there are not any bacteria out there and are only responding to the decreased availability of food. A supply of oxygen is required, as the growth of the fungus and the production of penicillin require aerobic conditions. The production of penicillin is stimulated by the addition of phenylacetic acid, but the concentration is critical as it is toxic to the fungus. Once the penicillin is released from the fungal cells, the compound is isolated from the fermenter's contents and purified by special biochemical processes. The process of extraction, purification and subsequent chemical modification of penicillin is referred to as downstream processing. The penicillin is extracted firstly by filtration, which separates fungal material from the medium, then by using solvent extraction to isolate the penicillin. The pH is reduced to between 2.0 and 2.5 and penicillin is extracted into an organic solvent such as amyl acetate. Penicillin is then re-extracted back into the aqueous buffer of pH 7.5, concentrated and then crystallised. Penicillin produced in this way is known as penicillin G, which may be converted into semi-synthetic penicillin's as means of overcoming the problems of penicillin-resistant strains of bacteria (see Antibiotic Resistance section). ...read more.


Bacteria most easily acquire resistance to a given antibiotic when bacteria are in a limited geographic environment with routine, consistent exposure to antibiotics or within a single individual on long-term antibiotic therapy. If antibiotics are used extensively, there is an increased likelihood of selection of a bacterial cell that is resistant to the effects of a given antibiotic. Another situation that encourages selection for antibiotic resistance is indiscriminate usage of antibiotics. If an antibiotic is not needed to treat a disease, such as a disease caused by a virus (antibiotics only work on bacteria), the use of antibiotics in this situation increases the opportunity to select a bacterial strain that is resistant to that antibiotic. There is increasing awareness of what we are doing to increase the presence of antibiotic-resistant strains of disease-causing bacteria - both in the medical community and in the food industry. The issue of antibiotic-resistant bacteria is a world-wide problem and continuous efforts are being made to reduce this threat to human health. If action is not taken soon to find ways of combating this problem we may find that in years to come people will die of diseases that we are successfully treating today. Laura Wing Biology PAC 04/27/07 1 / 4 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Cost effectiveness of mainstream bench cleaners against generic supermarket cleaners on the number of ...

    Therefore, it will suggest a cleaner performs better than it truly does and therefore compound the results. I will use areas next to each other for the before and after swabs. 2. Using an auto pipette, add 3cm3 of saline and allow 10 seconds to soak in and spread.

  2. Investigating how different concentrations of a antibiotic effects the growth of a bacterium.

    Penicillin kills bacteria by interfering with the ability to synthesize cell wall. The diagram to the right shows the chemical structure of Penicillin. THE GROWTH OF BACTERIA-BINARY FISSION The next point to consider on the scientific explanation is how the bacteria grow.

  1. Investigating the effect of sodium chloride on the action of antibiotics on bacteria growth

    This is thought to be as a result of the high concentration of sodium chloride ions in the lungs/ in areas of mucus accumulation. [4]"Escherichia coli are Gram-negative bacteria that belong to the g-proteobacteria. They primarily live in the mammalian gut.

  2. Follicular development

    signalling pathway (Vanhaesebroeck and Alees, 2000), resulting in the activation of phosphoinositide-dependent kinases (PDK) -1 and -2, which subsequently leads to protein kinase B (PKB) phosphorylation and activation. In 2003, Zeleznik et al, determined that the presence of protein kinase B is essential in the stimulation of granulosa cell differentiation by FSH, which acts via the Gs?

  1. The Origin of the Mitochondrion.

    The transfer of genes from one organism to another is a plausible explanation, but there are hurdles that would have to be crossed before the two genomes became fully integrated. If a mitochondrial gene were to transfer, it could be possible that the host may see it as an intruder

  2. Before resistance to antibiotics was noticed, the use of antibiotics had to become wide ...

    One major breakthrough was to introduce the flourine atom into the quinolone molecule. This produced several new antibiotics and another class was formed, the fluoroquinolones. Different halogen substituents were placed into the same postition as the flourine. Each showed differences in their effectiveness of antibacterial activity against Escherichia coli, the most effective being fluorine and chlorine.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work