Genetic engineering - bacterial cells to produce insulin
Laura Armstrong & Joe Wolfensohn
Teachers
Contents
Recall Questions
This topic requires prior knowledge of desirable traits and prokaryotic cell structure.
Give one desirable trait that might be genetically engineered into a crop.
Disease resistance, pest resistance, herbicide resistance or faster growth for increased yield.
What is a plasmid?
A small circular piece of DNA found in bacteria.
Name one product made by genetically engineered bacteria.
Human insulin.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains genetic engineering- making bacterial cells that produce insulin, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
What Is Genetic Engineering?
Genetic engineering is the process of modifying the genome of an organism by inserting a gene from another organism to give a desired characteristic.
-
Used in agriculture (e.g. disease-resistant crops).
-
Used in medicine (e.g. insulin production by bacteria).
Examples of Genetic Engineering
GM crops – this will be covered in the next study note but here are some examples of how we can genetically modify crops:
-
crops resistant to diseases / pests.
-
crops resistant to frost.
-
crops resistant to drought.
-
crops / foods with added nutrients.
-
crops with more / bigger fruits or higher yield.
-
crops with improved taste.
-
crops with improved shelf life.
Bacteria:
-
Genetically engineered to produce human insulin to treat diabetes
Steps in Genetic Engineering
In genetic engineering, genes from the chromosomes of humans and other organisms can be ‘cut out’ and transferred to cells of other organisms.
Higher tier only
-
Use enzymes to cut out the desired gene from DNA.
-
Insert the gene into a vector (e.g. plasmid or virus).
-
Insert the vector into the target cells (such as bacterial cells).
Example 1 - making human insulin using bacteria
-
The human insulin gene is cut out of human DNA using enzymes.
-
It is inserted into a plasmid vector.
-
The plasmid is inserted into bacterial cells.
-
The bacteria are cultured and begin to produce insulin.
-
All bacteria will contain the new gene as they use asexual reproduction so offspring are genetically identical.
-
This allows us to produce insulin on a large scale to treat diabetes.
No answer provided.
Key Terms
- Genetic engineering – Modifying DNA to give an organism a desired trait.
- GM crops – Plants that have had genes inserted to improve their characteristics.
- Plasmid – A small loop of DNA in bacteria, often used as a vector.
- Vector – A mechanism used to transfer DNA into cells (e.g. plasmid or virus).
No answer provided.
Exam Tip
Always mention a specific gene, the organism it is transferred to, and the resulting benefit. For high-tier (HT) questions, include the use of enzymes and vectors.
No answer provided.
Practice Questions
Question 1
Insulin is now made by a biotechnological process.
Complete the gaps in the sentences.
The first step in the process is that a special enzyme is used to cut
the insulin ___________________ out from a human ______________________ .
In a separate step, a ring of bacterial _______________________ is cut open
using a special enzyme.
These two pieces of genetic material are combined together to form a new plasmid ring which is inserted into a bacterium.
(3 marks)
gene or allele
chromosome
DNA
Question 2
Explain why large quantities of insulin are produced when this bacterium is put into a culture medium. (2 marks)
bacteria grow or reproduce
asexually, meaning all bacteria have the insulin gene.
More Practice
Try to answer the practice question from the TikTok video on your own, then watch the video to see how well you did!