Bacteria can be engineered to act as tiny factories for producing human proteins, a process fundamental to biotechnology and medicine.
The Process of Creating Human Proteins in Bacteria
Creating human proteins using bacteria involves several key steps. Essentially, the genetic instructions for building a human protein are inserted into bacterial cells, which then read these instructions and manufacture the protein.
Here is a simplified breakdown of the process:
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Introduction of the Human Gene:
- First, scientists isolate the specific gene that contains the instructions for making the desired human protein.
- This human gene is typically inserted into a small circular piece of DNA called a plasmid. Plasmids are commonly found in bacteria and can replicate independently.
- The plasmid, now containing the human gene, needs to be introduced into bacterial cells. Getting DNA across the bacterial cell wall and membrane can be challenging.
- The provided reference states: "This can be done using heat shock or electroporation, both of which make the bacterial cell wall permeable to DNA."
- Heat Shock: This method involves briefly exposing the bacteria and the plasmid DNA to a rapid temperature change (e.g., from ice to a warm bath). This sudden change creates temporary pores in the bacterial cell membrane, allowing the plasmid to enter.
- Electroporation: This technique uses a short electrical pulse to create temporary pores in the bacterial cell membrane, through which the plasmid DNA can pass.
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Replication and Expression:
- Once the plasmid containing the human gene is inside the bacterial cell, the bacteria are grown in a nutrient-rich environment.
- As the bacteria multiply, they also replicate the plasmid, creating many copies within each cell and throughout the bacterial population.
- More importantly, the bacteria's cellular machinery reads the instructions on the human gene within the plasmid.
- The provided reference explains the outcome: "The bacteria replicate, producing many copies of the plasmid and the human gene. The bacteria then express the gene, producing the human protein."
- "Expressing the gene" means the bacteria use their internal systems (like ribosomes) to translate the genetic code of the human gene into the corresponding human protein.
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Protein Collection and Purification:
- After the bacteria have produced a sufficient amount of the human protein, the protein needs to be collected.
- This usually involves breaking open the bacterial cells and separating the desired human protein from all the bacterial components and other proteins.
- Various purification techniques are used to obtain a clean sample of the human protein.
This technique, often referred to as recombinant DNA technology, allows for the large-scale production of valuable human proteins like insulin (for diabetes), human growth hormone, and many enzymes and antibodies, which are crucial for medical treatments and research.
