Download yr9&10 engineered insulin

B1b 6.5 Genetic engineering
Genetic engineering
Remember: In addition to their nucleoid
(main chromosome)bacteria have additional
small circular pieces of genetic material in
their cells called plasmids.
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B1b 6.5 Genetic engineering
Remind me about genes again
A human cell nucleus contains 46 chromosomes.
These chromosomes are made from DNA.
Along the length of the chromosome are genes.
One of these genes codes for the hormone insulin
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B1b 6.5 Genetic engineering
Genetic engineering
Sticky ends
It took decades of research to find out which
chromosome contained the insulin gene and where
the insulin gene was in that chromosome.
Finally the insulin gene was cut out of the chromosome
using a restriction enzyme that leaves “sticky ends”
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B1b 6.5 Genetic engineering
Genetic engineering
First the bacterium is cut
open using lysozyme
enzyme and the plasmid
is removed
Sticky ends
plasmid
First the bacterium was cut open using lysozyme
enzyme
Then the same restriction enzyme that was used to
remove the insulin gene is used to cut into the
plasmid leaving matching sticky ends
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B1b 6.5 Genetic engineering
Genetic engineering
The sticky ends on the insulin gene and the plasmid DNA are
matched up and joined using another enzyme called Ligase.
Ligase is rather like DNA glue
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B1b 6.5 Genetic engineering
Genetic engineering
Bacteria multiply rapidly and produce many millions of
copies of themselves, all able to make insulin using the
incorporated insulin gene.
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B1b 6.5 Genetic engineering
Genetic engineering
The insulin producing bacteria can be grown in large batches.
They secrete the insulin into the liquid medium that they grow in.
The liquid is collected and purified to produce sufficient insulin for all
diabetics.
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B1b 6.5 Genetic engineering
Engineered v Pig Insulin
• Engineered is better because it :
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Is identical to Human insulin
Is faster acting
Is less likely to cause immune reactions
Is less likely to transmit diseases
Can be produced fast enough to match
demand
• Has fewer ethical and religious objectors
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B1b 6.5 Genetic engineering
Insulin v pancreas transplant
• Advantages of injecting insulin
• Readily available to all diabetics
• Relatively inexpensive short term
• Disadvantages
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Only a treatment not permanent
Blood sugar requires constant monitoring
Diet needs constant control
Some patients find it difficult to inject themselves
Expensive over life of patient
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B1b 6.5 Genetic engineering
Insulin v pancreas transplant
• Advantages of pancreas transplant
• Permanent cure
• No more injections
• No more diet control
• Disadvantages
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Risk associated with surgery
Expensive one off treatment
Need immunosuppresant (anti-rejection) drugs
Immunosuppresants may lower immunity to
infectious disease
AQA Science © Nelson Thornes Ltd 2006
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B1b 6.5 Genetic engineering
Possible new treatment
Stem cells
It may be possible in future to take stored stem
cells from a person and encourage them to
differentiate into the Islets of Langerhans of
the pancreas (insulin and glucagon producing
cells)
This would mean the person would not need
anti rejection drugs after the operation as the
cells would be his own.
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