Genetic Modification (Genetic Engineering) (Edexcel IGCSE Science (Double Award): Biology): Flashcards
Exam code: 4SD0
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Define genetic modification.
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Define genetic modification.
The transfer of a gene, or section of DNA, from one organism into the DNA of another organism.
What do restriction enzymes do?
They cut DNA at specific sites, so the required gene can be cut out of the original organism's DNA.
Why are there different types of restriction enzyme?
Each targets a different DNA sequence, so a specific enzyme can be selected to cut out exactly the required piece of DNA.
Define sticky end.
The short, uneven end left on a piece of DNA after a restriction enzyme has cut it.
Two sticky ends made by the same restriction enzyme will match, so they can be joined.
Why is the plasmid cut with the same restriction enzyme?
So that the two sticky ends match each other, which is what allows them to join together.
What does DNA ligase do?
It joins pieces of DNA together — if two pieces have complementary sticky ends, ligase links them into a single unbroken molecule.
Which enzyme cuts DNA, and which one joins it?
Restriction enzymes cut DNA at specific sites
Ligase joins pieces of DNA together
Define vector.
Something that takes up a piece of DNA and inserts this recombinant DNA into other cells. Plasmids and viruses can act as vectors.
Which cells do viruses and plasmids transfer DNA into?
Viruses — into human cells or bacteria
Plasmids — into bacteria or yeast
How does a recombinant plasmid spread quickly?
When the bacteria reproduce, the plasmids are copied too, so as the bacteria multiply they all carry the plasmid and express the gene.
Why are genetically engineered bacteria placed in a fermenter?
So they can reproduce quickly in controlled conditions and make large quantities of the human protein.
＿＿＿＿＿＿＿＿ enzymes cut DNA at specific sites to release the required gene.
Restriction enzymes cut DNA at specific sites to release the required gene.
The enzyme ＿＿＿＿＿＿＿＿ joins the isolated gene to the cut plasmid.
The enzyme ligase joins the isolated gene to the cut plasmid.
True or False?
All restriction enzymes cut DNA in the same place.
False.
Different restriction enzymes target different DNA sequences, which is why a specific one can be chosen.
True or False?
A virus can act as a vector for genetic engineering.
True.
Both viruses and plasmids can take up DNA and insert it into other cells.
Why is genetically modified human insulin needed?
It is collected and purified for medical use to treat people with diabetes.
Describe how human insulin is made from GM bacteria.
Restriction enzymes cut the human insulin gene out of the chromosome, leaving sticky ends.
A bacterial plasmid is cut with the same enzyme, giving matching sticky ends.
DNA ligase joins the gene and plasmid into one molecule.
The recombinant plasmid is inserted into a bacterial cell.
The bacteria are grown in a fermenter, and all of them express the gene and make human insulin.
Define plasmid.
A circle of DNA found inside a bacterial cell, separate from the main bacterial chromosome.
Why must the plasmid be cut with the same restriction enzyme?
So that its sticky ends match those of the insulin gene, allowing DNA ligase to join them.
Why does the recombinant plasmid spread so quickly?
Because when the bacteria reproduce, the plasmids are copied too, so all the new bacteria carry it and express the human insulin gene.
Why are the GM bacteria placed in a fermenter?
So they reproduce quickly in controlled conditions and make large quantities of the human insulin protein.
Give three reasons bacteria are useful for genetic engineering.
They use the same genetic code, so they can 'read' human genes and make the same proteins
There are no ethical concerns over their manipulation and growth
Their plasmids sit separate from the main chromosome, so they are easy to remove and manipulate
Where in a human cell is the insulin gene found?
Within a human chromosome.
The insulin gene and the cut plasmid are joined together by ＿＿＿＿＿＿＿＿ enzyme.
The insulin gene and the cut plasmid are joined together by DNA ligase enzyme.
GM bacteria are grown in a ＿＿＿＿＿＿＿＿ to produce large quantities of human insulin.
GM bacteria are grown in a fermenter to produce large quantities of human insulin.
True or False?
Bacteria can read human genes because they share the same genetic code.
True.
This is why they can express a human gene and produce the same protein.
True or False?
A plasmid is part of the main bacterial chromosome.
False.
Plasmids are separate circles of DNA, which is what makes them easy to remove and manipulate.
Define genetically modified plant.
A plant that has had foreign genes inserted into its genome to give it new traits, such as pest or herbicide resistance, improved nutrition or drought tolerance.
How have wheat and maize been modified to resist insect pests?
They contain a gene from a bacterium that makes them produce a poison that kills insects, such as caterpillars, which improves crop yields.
Why are some crops made resistant to herbicides?
So that when the herbicide is sprayed, it only kills the weeds and does not affect the crop plant.
What is golden rice, and why was it developed?
Rice containing genes from another plant and a bacterium, so the grains produce a chemical the body turns into vitamin A.
It could help prevent deficiency diseases.
Why are some crops modified to be drought-resistant?
So they grow better in very dry conditions, which improves crop yields.
Give three advantages of GM crops.
Reduced use of herbicides and pesticides, which is better for the environment
Cheaper and less time-consuming for farmers
Increased yields, as crops do not compete with weeds or suffer pest damage
Why can GM seeds disadvantage smaller farmers?
Companies charge more for GM seeds to cover development costs, so smaller, poorer farmers cannot compete with larger farms.
Why is gene transfer to wild plants a concern?
Inserted genes could be transferred by pollination. If weeds gained herbicide resistance, the GM crop would lose its usefulness.
How can GM crops reduce the number of species on farmland?
Herbicide use leaves fewer plant species, which in turn affects the insects that feed on them and the insect-eating birds.
Give two further disadvantages of GM crops.
Increased dependency on the specific herbicides the crops resist, often made by the same companies
Some research suggests GM plants do not grow as well as non-GM plants
Golden rice was modified so its grains produce a chemical turned into vitamin ＿＿＿＿＿＿＿＿ in the body.
Golden rice was modified so its grains produce a chemical turned into vitamin A in the body.
Inserted genes could spread to wild plants by ＿＿＿＿＿＿＿＿.
Inserted genes could spread to wild plants by pollination.
True or False?
GM crops can reduce the amount of pesticide a farmer needs to use.
True.
Insect-resistant crops need less pesticide, which is better for the environment.
True or False?
The health effects of eating GM crops are fully understood.
False.
Some people feel the effects on human health have not been fully explored.
Define transgenic.
The transfer of genetic material from one species to a different species.
Define transgenic organism.
An organism containing DNA from a different species.
Define genetically modified organism.
Any organism that has had new genetic material introduced. Abbreviated to GMO.
What is genetic modification?
The process of artificially altering the DNA of an organism to give it new traits, by combining DNA from different sources.
What is the relationship between GMOs and transgenic organisms?
All transgenic organisms are GMOs, but not all GMOs are transgenic.
Give an example of a GMO that is not transgenic.
A plant modified with DNA from the same species. To be transgenic it would need DNA from a different species.
What distinguishes a transgenic organism from other GMOs?
Its genetic material has been transferred from one species into a different species — not within the same species.
Transgenic means the transfer of genetic material between different ＿＿＿＿＿＿＿＿.
Transgenic means the transfer of genetic material between different species.
Any organism that has had new genetic material introduced is called a ＿＿＿＿＿＿＿＿.
Any organism that has had new genetic material introduced is called a GMO.
True or False?
Every genetically modified organism is transgenic.
False.
All transgenic organisms are GMOs, but a GMO modified with DNA from its own species is not transgenic.
True or False?
Genetic engineering and genetic modification mean the same thing.
True.
Both describe artificially altering an organism's DNA to give it new traits.
Is a bacterium given the human insulin gene transgenic?
Yes — the gene has come from a different species, so it is both a GMO and transgenic.
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