Genetic modification Cambridge IGCSE Biology (9–1) revision
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In plain words
People with diabetes inject insulin. It used to come from pigs. Now it is made by bacteria that have been given the human gene for insulin: a gene cut out of one living thing and put into another. That is genetic modification.
Three things to know
- Genetic modification is changing the genetic material of an organism by removing, changing or inserting individual genes. Examples: bacteria that make human insulin; crops resistant to insect pests or herbicides; rice with extra vitamins.
- Method: a restriction enzyme cuts the gene out of human DNA. The same enzyme cuts open a bacterial plasmid. DNA ligase joins the gene into the plasmid. The plasmid is put into a bacterium, which multiplies and makes the protein.
- GM crops can give bigger yields with less pesticide, but people worry about genes spreading to wild plants, effects on other species, and seed costs for farmers.
Tips and tricks
- Restriction enzymes are the scissors. Ligase is the glue. The plasmid is the delivery van (the vector).
- Using the same restriction enzyme on the gene and the plasmid gives matching "sticky ends", so they fit together.
It lands in your notebook with its questions as flashcards.
Genetic modification: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What does a restriction enzyme do?
It cuts at particular base sequences.
What does DNA ligase do?
It seals the gene into the plasmid.
What is a plasmid?
It is used to carry a gene into a bacterium.
Which human protein is made by genetically modified bacteria?
It is used to treat diabetes.
Which is a benefit of some GM crops?
Less insecticide has to be sprayed.
Quiz
5 questions
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Worksheet
3 questions, 8 marks. Write your answers on paper, then check them.
Genetic modification
Cambridge IGCSE Biology (9–1) 0970 · 8 marks · papermunch.org
Name ______________________________ Date ______________
State what is meant by genetic modification.[2]
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Changing the genetic material of an organism by removing, changing or inserting individual genes.
Describe how bacteria are modified to produce human insulin.[4]
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The insulin gene is cut from human DNA using a restriction enzyme. A bacterial plasmid is cut open with the same restriction enzyme. The gene is joined into the plasmid using DNA ligase. The plasmid is put into a bacterium, which multiplies and produces insulin.
Give one advantage and one possible disadvantage of genetically modified crops.[2]
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Advantage: higher yield, or resistance to pests so less pesticide is used, or better nutritional value. Disadvantage: the gene could spread to wild plants; possible effects on other species or food chains; cost of seed.
Answers: Genetic modification
- 1. Changing the genetic material of an organism by removing, changing or inserting individual genes.
- 2. The insulin gene is cut from human DNA using a restriction enzyme. A bacterial plasmid is cut open with the same restriction enzyme. The gene is joined into the plasmid using DNA ligase. The plasmid is put into a bacterium, which multiplies and produces insulin.
- 3. Advantage: higher yield, or resistance to pests so less pesticide is used, or better nutritional value. Disadvantage: the gene could spread to wild plants; possible effects on other species or food chains; cost of seed.