IGCSE curriculum biology

1. Biotechnology
and
Genetic Engineering

4. role of anaerobic respiration in
yeast during production of ethanol for
biofuels
• Micro-organisms that bring about fermentation are using the
chemical reaction to produce energy, which they need for their
living processes.
• The reactions that are useful in fermentation biotechnology are
mostly those that produce incompletely oxidised compounds.
• Ethanol (alcohol), produced from fermented sugar or surplus
grain, could replace, or at least supplement, petrol, oil from
rapeseed or sunflower seed, can with suitable treatment
replace diesel fuel

6. Advantage
• renewable resource
• Ethanol/diesel produces less pollution than petrol.
Disadvantage
• not yet economical
– the energy used to grow, fertilise and harvest sugar-cane,
plus the cost of extracting the sugar and converting it to
ethanol, uses more energy than the ethanol releases when
burned.
– environmental costs

7. Role of anaerobic respiration in
yeast during bread-making
• Yeast is the micro-organism used in bread-
making but the only fermentation product
needed is carbon dioxide.
• The carbon dioxide makes bubbles in the
bread dough.
• These bubbles make the bread ‘light’ in
texture.

9. Pectinases
• Pectinases are used to separate the juices from
fruit such as apples.
• The enzymes can be extracted from fungi such as
Aspergillus niger.
• They work by breaking down pectin, the jelly-like
substance that sticks plant cell walls to each other.
• The enzymes can also be used to clarify fruit juice and
wine (make it more transparent).
• During the breakdown process a number of different
polysaccharides are released, which make the juice
cloudy, but pectinases break these down to make the
juice clearer.
• The sugars produced also make the juice sweeter.

10. Biological Washing Powder
• Many stains on clothes are organic molecules – oil
from skin, protein from blood, fat and protein from
food
• Biological washing powder contain enzymes similar
to the digestive enzymes produced in the alimentary
canal that help to break down large food molecules.

11. Lactose-Free Milk

12. Penicillin Production
• Penicillin was the first antibiotic discovered
in 1928 by Alexander Fleming
• He noticed that some bacteria he had left in a
Petri dish had been killed by the naturally
occurring Penicillium mould
• The penicillium mould produces a chemical to
prevent it being infected by certain types of
bacteria
• The chemical was isolated and
named penicillin
• Since the discovery of penicillin, methods

17. Recombinant DNA
• The ability to combine
the DNA of one
organism with the
DNA of another
organism.
• Recombinant DNA
technology was first
used in the 1970’s
with bacteria.

18. Recombinant Bacteria
1. Remove bacterial DNA
(plasmid).
2. Cut the Bacterial DNA with
“restriction enzymes”.
3. Cut the DNA from another
organism with “restriction
enzymes”.
4. Combine the cut pieces of DNA
together with another enzyme
and insert them into bacteria.
5. Reproduce the recombinant
bacteria.
6. The foreign genes will be
expressed in the bacteria.