A biotechnology company has produced a genetically modified (GM) bacterium that contains a human gene. The bacterium produces a useful protein that can be used as a medicine. Explain how the bacterium is able to produce this human protein, and evaluate one advantage and one disadvantage of using GM bacteria to produce medicines in this way.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Genetic modification involves inserting a gene from one organism into another. Bacteria can be modified to carry human genes and then grown in large fermenters to produce useful proteins such as insulin.
Model answer (5 marks)
The human gene contains the DNA sequence that codes for a specific protein.
The gene is inserted into the bacterial genome (or a plasmid that replicates in the bacterium).
The bacterium transcribes the inserted gene into mRNA and translates it using its ribosomes, producing the human protein.
Advantage: Bacteria grow rapidly and can be cultured in large fermenters, allowing quick, cheap production of large quantities of the medicine.
Disadvantage: There are safety and ethical concerns – the GM bacterium could escape into the environment and cause unpredictable effects, or the manipulation of genomes raises ethical issues.
The gene is inserted into the bacterial genome (or a plasmid that replicates in the bacterium).
The bacterium transcribes the inserted gene into mRNA and translates it using its ribosomes, producing the human protein.
Advantage: Bacteria grow rapidly and can be cultured in large fermenters, allowing quick, cheap production of large quantities of the medicine.
Disadvantage: There are safety and ethical concerns – the GM bacterium could escape into the environment and cause unpredictable effects, or the manipulation of genomes raises ethical issues.
Examiner tips
- Use the exact terminology: gene, DNA, transcription, translation, ribosomes, plasmid, fermenter. Show the sequence of events: insertion → transcription → translation → protein. Mention rapid growth and cost‑effectiveness as the advantage. State a clear safety/ethical risk as the disadvantage.
- common_mistakes
- :
- Saying the bacterium ‘makes’ the protein without mentioning transcription/translation. Forgetting to note that the gene is inserted into the bacterial genome or plasmid. Giving a non‑specific disadvantage such as ‘cost’ instead of safety/ethical concerns.
Mark scheme (5 marks)
- The human gene (section of DNA) codes for the specific protein / codes for a specific amino acid sequence
- The human gene has been inserted into the bacterium's DNA / genome
- The bacterium uses the gene to produce / synthesise the human protein
- Advantage: large quantities of the protein / medicine can be produced quickly / cheaply (accept: bacteria reproduce rapidly so large amounts can be made)
- Disadvantage: there are ethical concerns about genetic modification / there is a risk the GM bacterium could escape into the environment and have unpredictable effects (accept: concerns about safety or ethics of altering an organism's genome)
Key terms in this question
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →