Chapter 17 - Microorganisms and Biotechnology 

Microorganisms:

Tiny living things that can not be seen through the naked eyes.

1. Virus:

• %%Noncellular%%

• Strictly %%parasites%%

• On the border line of living and non living organisms.

• They do not show any life activity outside the host cells.

• They have crystalline shape outside the %%host cell%%.

• They contain %%nucleic acid%%.

• %%Multiply%% inside the host cell.

• Exist in %%various shapes%%

• Rod shaped

• Polyhedral

• Spherical

• 10 to 100 times smaller than bacteria

• Their body consists of %%protein coat%%

• A virus nears a host cell. It attaches itself with the host cell surface with the help of sticking protein. It makes a hole through the wall of the host cell. It injects its DNA/RNA into the host cytoplasm. The viral DNA can insert itself into the host DNA and %%multiplies%% with the multiplication of the host cell. It uses the machinery of the host cell in the cytoplasm and instructs the host cytoplasm to make new viruses. The viruses mature inside the host and cause the host cell to burst.

  

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1. Bacteria:

• %%Unicellular%%

• Cell wall made of %%murein%%

• Lack of double membrane bound organelles

• A double standard circular DNA embedded in the cytoplasm. No nucleus

• May or may not have %%flagella%%

• Shapes: spherical, rod, spiral

• Bacteria obtain their nutrition from other organisms.

  

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1. Fungi:

• May be %%unicellular%% or %%multicellular%%

• The multi cellular forms consist of thread like structures called %%hyphae%%. The hyphae are interwoven together to make the vegetable body of the fungus called %%mycelium%%.

• Each hypha consist of a cell wall made of %%chitin%%

• One or nucleus may be present

• Their mode of nutrition is %%heterotrophic%%.

  

Biotechnology:

The implementation of biological processes for the benefits of mankind.

• %%FERMENTATION%%:

  A biological process which is used for the formation of many food products.

  Glucose —> Alcohol + CO2

               **OR**

Glucose —> Lactic Acid

- CO2 for making bread

- alcohol for beer making

- lactic acid for yoghurt making

• %%BREAD MAKING%%

  • Dough is placed in molds and left at warm temperature for 2-3 hours.
  • During this process anaerobic respiration of yeast produces CO2 and alcohol.
  • CO2 expands due to high temperatures. As it escapes through dough it causes the dough to rise and become soft. %%Yeast%% is killed in the process and the outer crust hardens which maintains the shape of bread.

• %%BEER MAKING%%

  • Soak seeds in water. Allow them to germinate for 2-3 days

  • Roast the germinated seeds grind them.

  • Add hot water into the ground grains . It makes wort.

  • Add yeast into it which converts sugar alcohol.

  • As %%yeast respires%%, it produces CO2. It escapes from the medium and produces foam at the top of the wort. It creates %%anaerobic conditions.%%

    

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• %%YOGURT MAKING%%

  • Pasteurization at 60 degree Celsius for 30 mins
  • Let it cook to room temperature
  • Add starter culture into it
  • Leave the milk to ferment overnight
  • %%Streptococcus%% is aerobic bacterium, it absorbs oxygen from the milk and produces anaerobic conditions
  • %%Lactobacillus%% converts milk sugar into lactic acid. It drops pH of milk which causes milk protein to solidify, the curdled milk is called yoghurt.

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Fermenter:

Transfer of human insulin gene into bacteria E.coli

• %%Human insulin gene%% is isolated by adding restriction enzyme that cuts the gene, producing sticky ends.
• %%Plasmid%% from E.coli is cut with the same restriction enzyme. This produces sticky ends complementary to those of the insulin gene.
• Mix the plasmid with the DNA fragment containing the human insulin gene. The human insulin gene will bind to the plasmid by complementary base pairing between their sticky ends, forming recombinant plasmid
• Add the %%enzyme DNA ligase%% to seal the nick.
• Mix the recombinant plasmid with E.coli bacterium. Heat shock or electric
  shock is applied to open up pores on the cell surface membrane of the bacterium for plasmid to enter. The E.coli that contains this recombinant plasmid is a transgenic bacterium
• The transgenic bacteria are placed in large fermenters under optimal conditions for growth and reproduction.
• Fermenter consists of:
  • a nutrient broth containing glucose water and salts
  • 37°C temperature maintained by a %%temperature probe%%
  • optimal pH maintained by a pH probe
  • air supply for aeration and a %%stirrer%% to mix substances evenly.
• At the end of fermentation, the %%insulin protein%% is extracted and purified before it can be used.

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