A gene is a section of DNA that codes for the production of a protein. In I/GCSE Biology, the protein produced could be: 👇👇👇

• An enzyme that controls a particular reaction inside a cell or outside
• A hormone
• A structural protein like keratin in hair, collagen in skin or one of the money proteins found in the membranes of cells
• A protein with a specific function such as haemoglobin or an antibody

Genes can be moved from between different species by cutting a section (gene) out of the DNA of one species and inserted into the DNA of another species. This new DNA is called recombinant DNA. The organism that receives the new gene is a transgenic organism. The organism now has an added capability and will manufacture the protein its new gene codes for. For example, a bacterium receiving the gene from a human that codes for insulin production will make human insulin.

Restriction enzymes cut DNA molecules at specific points, whilst ligase enzymes join cut ends of DNA molecules. Some restriction enzymes make cuts that produce ‘blunt ends’. Others make ‘sticky ends’, which are more easily joined by ligase enzymes.

To transfer a gene from any cell into a bacterium, biologists must insert the gene into a plasmid (small circular pieces of DNA found in bacterium). In I/GCSE Biology, the plasmid is called a vector because it is the means of transferring the gene. The bacterium is then transferred to a fermenter.

Another vector that could be used is a virus that attacks a bacterium. It does this by attaching to the cell wall of the bacterium and injecting its own DNA into the bacterial cell. This DNA becomes incorporated into the DNA of the host cell, and eventually causes the production of many virus particles.

In I/GCSE Biology, different bacteria have been genetically modified to manufacture a range of products. Once they’ve been modified, they are cultured in fermenters to produce large amounts of the product such as:

• Human Insulin:
• Enzymes for Washing Powders:
• Human Growth Hormone:

That's the end of the topic!

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