I/GCSE Biology - Immobilised Enzymes and Genetic Modification

Immobilised Enzymes 🧬

We immobilise enzymes to make them easier to remove (and use elsewhere). We can immobilise enzymes by either attaching them to a solid surface or capturing them in alginate beads. We can immobilise lactase to produce lactose-free milk. 

Method:

1. Mix sodium alginate and lactase in a syringe
2. Add the mixture to a beaker of calcium chloride, drop by drop
3. Collect the beads that form
4. Fill a burette/large syringe with the beads with the tap open and a beaker at the bottom
5. Pour normal milk over the top
6. Let the milk flow through and the immobilised lactase will break the lactose down into glucose and galactose.
7. Test that it has work by checking if glucose is present (use a glucose test *****)

Pectinase is used to extract the juice from apples. It breaks down pectin in the walls which then forces the cell to release its (apple) juices. This is another example of an immobilised enzyme. This may be asked in I/GCSE Biology.

GM for Human Insulin🕺

1. Cut the gene for human insulin from a chromosome using a restriction enzyme (it automatically detects the right gene)
2. Cut a bacterial plasmid using a restriction, leaving sticky ends (unpaired DNA bases that will pair with the corresponding base)
3. Mix the gene and plasmid together with ligase enzyme which will make the gene fill in the sticky ends, producing recombinant DNA (2 different DNAs stuck together)
4. Put the recombinant DNA into a bacteria and let it divide, producing lots of human insulin
5. This creates transgenic bacteria. (A gene is transferred from another species).

GM in Plants🌸

1. A plant cell resistant to herbicide is taken and the gene responsible is cut using a restriction enzyme.
2. The circular DNA of agrobacterium tumafaciens is extracted and a section cut using restriction enzyme, leaving sticky ends.
3. The resistant gene is inserted and mixed with ligase enzyme, filling in the sticky ends – producing recombinant DNA.
4. 4.       The modified DNA is then inserted back into the vector, agrobacterium tumafaciens.
5. 5.       It is then allowed to multiply exponentially in a fermenter
6. 6.       Plants are then sprayed with agrobacterium tumafaciens and a crown gall is formed
7. 7.       The crown gall moves to other plants
8. 8.       Lots of plants get resistant to herbicide

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Drafted by Catrina (Biology)