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Biotechnology and Genetic Engineering

  • Bacteria are useful in biotechnology and genetic engineering due to their rapid reproduction rate and their ability to make complex molecules

Why Bacteria are Useful in Biotechnology and Genetic Engineering

  • No one minds what is done to bacteria and fungi. There are no ethical issues like those that might arise if we used animals
  • Although bacterial cells are very different from animal and plant cells; in fact, we all share the same kind of genetic material; DNA, the genetic code is the same for bacteria as it is for humans and all other organisms. So we can take a gene from a human cell and place it into a bacterial cell, it will work to produce the human protein
  • Bacteria also have loops of DNA called plasmids. These are quite easy to transfer from one cell to another. We can use plasmids for moving genes from one organism’s cell to another

The Role of Anaerobic Respiration in Yeast during the Production of Ethanol for Bio-fuels

  • To make beer, yeast is dissolved in a warm liquid containing the sugar maltose
  • The yeast respires anaerobically by a process called fermentation
  • This process produces ethanol, making the drink alcoholic, and carbon-dioxide which makes the drink fizzy

The Role of Anaerobic Respiration in Yeast during Bread Making

  • Yeast is mixed with water and sugar to activate it
  • The mixture is added to flour to make dough, and left in a warm place
  • Thou dough rises as the yeast respires and releases carbon-dioxide, which gets trapped in the dough
  • When the dough is cooked, the high temperature kills the yeast and evaporated any alcohol formed
  • Air spaces are left where the carbon-dioxide was trapped. Which gives the bread a light texture

Pectinase in Fruit Juice Production

  • Juice is extracted more quickly if pectinase is added to the fruit than if it is not
  • The effect of pectinase varies on different kinds of fruits
  • People cannot tells the difference between juice extracted with pectinase and the juice not extracted with pectinase
  • Pectinase added to the extracted juice can make it clear

Biological Washing Powders

  • Biological washing powders contain protease and lipase to remove stains and fat/grease from clothes
  • The enzymes break down proteins or fats on the fabric, forming water-soluble substances that can be washed away
  • This makes the washing powder more effective than detergent alone, especially at lower temperatures but if the temperature is too high, the enzyme will be denatured

Lactose-free Milk

  • Lactose is the sugar found in milk
  • It can be broken down by the enzyme lactase into glucose and galactose
  • However, some people lack this enzyme and so cannot break down lactose leading to lactose intolerance
  • People that are lactose intolerant need to drink milk that is lactose-free
  • Lactose-free milk can be made in two ways:
    • The first involves adding the enzymes lactose to the milk so the milk contains the enzyme
    • The second way involves immobilizing the enzyme on a surface or in beads of a porous material. The milk is then allowed to flow past the beads or surface with the immobilized lactase. This method avoids having lactase in the milk

Antibodies

  • When micro-organisms are used for the production of antibiotics, it is not their fermentation products that are wanted, but complex organic compounds, called antibiotics that they synthesize
  • Most of the antibiotics we use come from bacteria or fungi that live in the soil
  • The function of the antibiotics in this situation is not clear
  • One theory suggests that the chemical help to suppress competition for limited food resources, but the evidence does not support this theory
  • One of the most prolific sources of antibiotics is Actinomycetes. These are filamentous bacteria that resemble microscopic mould fungi
  • The actinomycete Streptomyces produces the antibiotic streptomycin
  • Perhaps the best known antibiotic is penicillin, which is produced by the mould fungus Penicillium and was discovered by Sir Alexander Fleming in 1928
  • Penicillin is still an important antibiotic but it is produced by mutant forms of a different species of penicillium from that study by Flwming
  • The different mutant forms of the fungus produce types of penicillin
  • The penicillin types are chemically altered i the laboratory to make them more effective and to ‘tailor’ them for use with different diseases
  • ‘Ampicillin’, ‘methicillin’, and ‘oxacillin’ are examples
  • Anitbiotics attack bacteria in a veriety of ways
  • Some of them disrupt the production of the cell wall and so prevent the bacteria from reproducing or even cause them to burst open
  • Some interfere with protein synthesis and thus arrest bacterial growth
  • Those that stop bacteria from reproducing are said to be bacteriostatic
  • Those that kill the bacteria are bacteriocidal
  • Animal cells do not have cell walls, and the cell structures involved in protein production are different
  • Consequently, antibiotics do not damage human cells although they may produce some side effects such as allergic reactions

Genetic Engineering

  • Genetic engineering is changing the genetic material of an organism by removing, changing, or inserting individual genes
  • Examples of genetic engineering:
    • the insertion of human genes into bacteria to produce insulin
    • the insertion of genes into crop plants to confer resistance to herbicides
    • the insertion of genes into crop plants to confer resistance to insect pests
    • the insertion of genes into crop plants to provide additional vitamins

Genetic Engineering using Bacterial Production of a Human Protein

  • Extraction of the gene for insulin from human cells, this is done using enzymes called restriction enzymes which leave sticky ends
  • The particular length of the DNA is identified and extracted from other DNA
  • We use plasmid to insert DNA into a bacterium
  • The DNA plasmid is cut with the same restriction enzyme so it will leave complimentary sticky ends to the ones on the human DNA
  • The human insulin gene and cut plasmids are now mixed together
  • The sticky ends on the insulin gene join together with the sticky ends on the plasmids
  • An enzyme called DNA ligase links the two strands firmly together
  • Now we have plasmids that contain human insulin gene called recombinant plasmids
  • Plasmid is now inserted into the bacteria and some of them take these plasmids into their cells
  • These bacteria are put in fermenters to reproduce asexually to form a larger production

Advantages of Genetically Modified Crops

  • Resistance to herbicides
  • GM cotton plants contain By that is toxic to insects
  • GM rice produce more vitamin A than normal rice

Disadvantages of Genetically Modified Crops

  • Herbicide resistant genes might spread to plants growing nearby, producing weeds that cannot be killed with herbicides any longer
  • Some pests are evolving to become resistant to Bt toxin
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