Genetic engineering and biotechnology

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Notas de aula

Big idea: editing the instructions of life

Big idea (key concept): Systems. Every cell runs on a system of genes, proteins and enzymes. Genetic engineering changes one part of that system, and the change can ripple through the organism, the farm or the environment.
Related concept: Consequences. New technology brings benefits and risks. Scientists, farmers, patients and governments judge them differently, so we practise weighing evidence as well as values.
Global context: Fairness and development. Who gets the medicines, who can afford the seeds, and who decides the rules? These are questions about fairness between people and between countries.
Selective breeding means choosing parents with useful features, breeding them, and repeating over many generations. It only uses variation that already exists in the species, and it takes a long time.
Genetic engineering means taking a gene from one organism and putting it into the cells of another so that it has a new feature. The gene can come from a different species, and the change appears in a single generation. An organism changed this way is called genetically modified (GM).

The steps and tools of genetic engineering

Step 1: find and cut out the gene. Restriction enzymes are enzymes that cut DNA at a specific base sequence. Often they leave short single-stranded ends called sticky ends.
Step 2: choose a vector. A vector carries the gene into the host cell. A common vector is a plasmid, a small ring of DNA found in bacteria. Viruses can also be used as vectors.
Step 3: cut the plasmid with the same restriction enzyme. The cut plasmid has sticky ends that are complementary to the ends of the gene, so the two fit together.
Step 4: join them. The enzyme DNA ligase joins the gene to the plasmid. The result is a recombinant plasmid, which contains DNA from two sources.
Step 5: put the plasmid into host cells such as bacteria, then grow the cells. Plasmids often carry a marker gene (for example one that gives antibiotic resistance) so that scientists can pick out the bacteria that took up the plasmid.
Step 6: collect the product. Bacteria reproduce quickly, so one modified cell soon becomes millions. The genetic code is almost the same in all organisms, so a bacterium can read a human gene and build the human protein.

Building a recombinant plasmid

Uses: medicines and crops

Human insulin. People with type 1 diabetes cannot make enough insulin. Until the early 1980s insulin was extracted from the pancreases of pigs and cattle. Today the human insulin gene is put into bacteria, which are grown in large tanks. The insulin they make has the same amino acid sequence as human insulin.
Insect-resistant crops. The Bt gene comes from a soil bacterium. When it is put into a crop such as maize, the plant makes a protein that is toxic to certain insect pests, for example some caterpillars. In many studies this has meant farmers use less insecticide on these crops.
Nutrient-enriched crops. Golden Rice has been modified to make β-carotene, which the body can turn into vitamin A. It was developed to help tackle vitamin A deficiency, a serious problem in some countries. How useful it will be compared with other approaches is still debated.
Other aims include crops that tolerate a particular herbicide, crops that tolerate drought or salty soil, and animals that make useful proteins in their milk.
Each use has a specific purpose. Judging a technology means asking: what problem does it solve, and for whom?

Three uses of genetic modification

Cloning

A clone is an organism that is genetically identical to its parent. Cloning does not add any new alleles, but it can copy a valuable plant or animal exactly.
Plant tissue culture. Small pieces of tissue from the meristem at a shoot or root tip are placed on a sterile jelly (agar) containing nutrients and plant hormones. Their cells divide by mitosis and grow into many identical plantlets. Growers use this to produce thousands of identical plants, or to save rare species.
Animal cloning by nuclear transfer. The nucleus is removed from an unfertilised egg cell. A nucleus from a body cell of the animal to be copied is put in its place. A small electric shock makes the egg start dividing, and the embryo is placed in a surrogate mother. This is how Dolly the sheep was produced in 1996. Many attempts failed for each success.
Because clones share the same alleles, a whole crop of clones can be wiped out by the same disease. There is less genetic variation to give some individuals a chance of surviving.
Clones can still differ, because the environment (food, light, injury) affects how they grow.

Cloning plants by tissue culture

Benefits, risks and ethics: evaluating the evidence

Possible benefits. More affordable and reliable medicines; crops that lose less to pests and so may need less insecticide; foods with added nutrients; faster results than selective breeding.
Concerns that people raise. Genes might spread by pollen to wild relatives or non-GM crops. A herbicide-tolerant crop can encourage heavy use of one herbicide, and weeds may become resistant. Some people worry about effects on other insects, or on health, and ask for long-term monitoring. Seeds may be patented, so small farmers can find them expensive.
What the evidence says. Regulators test GM foods before they are approved, and many scientific reviews have found approved GM foods as safe to eat as their non-GM equivalents. Environmental effects depend on the crop, the trait and how it is farmed, so each case is judged separately.
Science and values. Evidence can tell us whether a protein is toxic to insects. It cannot alone tell us whether it is right to alter an organism's genes, how to share the benefits, or how much risk is acceptable. Those are value judgements, and different people and cultures weigh them differently.
Useful questions to ask: Who did the study and who paid for it? How many plants, animals or people were tested? Was it repeated by independent scientists? Who benefits and who carries the risk? What are the alternatives?

Think like a scientist: testing a claim

Claim: a seed company says its new insect-resistant maize loses less leaf to caterpillars. How could you test it fairly?
Take leaf discs of the same size from GM maize and from ordinary (non-GM) maize of the same variety, grown in the same soil and light. Place equal numbers of discs in dishes with the same number and age of caterpillars.
The independent variable is the type of maize (GM or non-GM). The dependent variable is the leaf area eaten after 24 hours, or the mass of leaf eaten.
Control variables: disc size, number and age of caterpillars, temperature, time, and the leaf age. Use at least five dishes per type and calculate a mean so that chance matters less.
Inquiry task 1: write a method for this test and say how you would record the results. Inquiry task 2: a farm trial found the GM crop had a higher mean yield at three of four farms, and the seed company paid for the trial. Evaluate how far the data supports the claim, and say what extra evidence you would want.

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CADASTRE-SE — GRÁTIS ENTRAR

Questões de prática

Prévia grátis — 8 de 51 perguntas. Cadastre-se para ver todas.

1.What is genetic engineering?
Easy
- AChoosing parents with useful features and breeding them over many generations
- BMoving a gene from one organism into another to give it a new feature
- CMaking an identical copy of an organism from one of its cells
- DMixing two different foods to make a new product
2.Which process uses only the variation that already exists in a species?
Easy
- ASelective breeding
- BGenetic engineering using a plasmid
- CMoving a gene between two species
- DCutting DNA with a restriction enzyme
3.Genetic engineering can move a gene from one species into a different species.
Easy
True or false?
4.Selective breeding changes an organism's genes directly in a single generation.
Easy
True or false?
5.Which type of enzyme cuts DNA at a specific base sequence?
Easy
- AA DNA ligase enzyme
- BA lipase enzyme
- CA restriction enzyme
- DAn amylase enzyme
6.Which enzyme joins a gene into a cut plasmid?
Easy
- ARestriction enzyme
- BProtease
- CCatalase
- DDNA ligase
7.What is a vector in genetic engineering?
Easy
- AA carrier, such as a plasmid, that takes a gene into a cell
- BAn enzyme that digests a gene so that it can be read
- CA disease-causing bacterium found in the soil sample
- DA machine that measures the amount of DNA in a cell
8.Complete the sentence.
Easy
A small ring of DNA in a bacterium that can be used as a vector is called a ____.

Mais perguntas

9.Which type of organism is usually used to make human insulin by genetic engineering?
Easy
- AViruses
- BPigs
- CBacteria
- DMaize plants
10.Before genetically modified bacteria were used, insulin for people with diabetes was extracted from animal pancreases.
Easy
True or false?
11.What does the Bt gene give to a crop such as maize?
Easy
- AThe ability to grow without any sunlight
- BA protein toxic to certain insect pests
- CResistance to every disease that affects it
- DFruit that ripens within a single day
12.Match each part of genetic engineering to its job.
Easy
- Restriction enzyme
- DNA ligase
- Plasmid
- Host bacterium
- Joins pieces of DNA together
- Grows and makes the protein
- Cuts DNA at a specific sequence
- Carries the gene into the cell
13.Put the main steps of making a genetically modified bacterium in order.
Easy
- Put the recombinant plasmid into bacteria
- Cut out the gene with a restriction enzyme
- Grow the bacteria and collect the product
- Cut a plasmid with the same enzyme
- Join the gene into the plasmid with DNA ligase
14.What is a clone?
Easy
- AAn organism with genes from two different species
- BAn organism that has a harmful mutation
- CAn organism that is genetically identical to its parent
- DAn organism grown only in a laboratory dish
15.In plant tissue culture, why are the new plants genetically identical?
Easy
- AThey are all made by meiosis inside the dish
- BThey each take their genes from the nutrient jelly
- CThey are all pollinated by the same type of insect
- DThey all grow from one parent plant by mitosis
16.A GM organism is one whose genome has been changed by adding a gene using genetic engineering.
Easy
True or false?
17.Which of these are made or improved using genetic engineering? (select all that apply)
Easy
- AHuman insulin made by bacteria
- BInsect-resistant maize
- CGolden Rice with β-carotene
- DA sheepdog bred to be calm
- EA wheat plant produced by crossing two wheat varieties
18.Which animal was the first mammal cloned from an adult body cell?
Easy
- AA mouse called Mickey
- BDolly the sheep
- CA bull called Taurus
- DA dog called Rex
19.Complete the sentence.
Easy
Restriction enzymes cut DNA and DNA ____ joins it together again.
20.Which of these is a concern some people raise about GM crops?
Easy
- AGenes might spread to wild relatives by pollen
- BThe crops always taste unpleasant to everyone
- CThe plants can no longer make any seeds at all
- DThe crops need no water to grow in any soil
21.Why must the gene and the plasmid be cut with the same restriction enzyme?
Medium
- AThe enzyme changes the gene so that it works in bacteria
- BThe two pieces then have complementary sticky ends
- CThe enzyme makes the plasmid reproduce much faster
- DIt removes the need for any other enzyme at all
22.Which statement correctly compares selective breeding with genetic engineering?
Medium
- ASelective breeding is faster and more precise than genetic engineering because genes are chosen directly
- BBoth methods can only ever use genes that are already present in the same species
- CGenetic engineering needs many generations of breeding, but selective breeding gives a result in one generation
- DGenetic engineering can add a gene from another species in one generation, but selective breeding uses existing variation and takes many generations
23.Why are bacteria useful host cells for making a protein such as insulin?
Medium
- ABacteria already contain the human insulin gene inside
- BBacteria never need any nutrients in order to grow well
- COne modified cell divides quickly, giving millions of copies
- DBacteria cannot be harmed by restriction enzymes at all
24.Why can a bacterium make a human protein when it is given a human gene?
Medium
- AThe genetic code is almost the same in all organisms
- BHuman genes are always shorter than bacterial genes
- CThe plasmid turns the bacterium into a type of human cell
- DBacteria have a nucleus in the same way as human cells
25.Why is insulin made by genetically modified bacteria the same as human insulin?
Medium
- ABacteria and humans share the same body temperature
- BThe human insulin gene gives the same amino acid sequence
- CBacteria change the insulin to match each separate patient
- DThe bacteria are first grown inside a human pancreas
26.Golden Rice was developed to help with which problem?
Medium
- ARice plants taking far too long to start flowering
- BRice plants needing far too much sunlight to grow
- CRice crops being attacked by large numbers of caterpillars
- DVitamin A deficiency, because it makes β-carotene
27.Plants grown by tissue culture from one parent plant contain new combinations of alleles.
Medium
True or false?
28.How was Dolly the sheep produced?
Medium
- AAn adult body-cell nucleus was put into an egg cell with its nucleus removed
- BTwo different sheep egg cells were fused together in a dish
- CA sheep embryo was split into two separate halves early on
- DA gene for very fast growth was added into a young lamb
29.A newspaper says a new GM crop is safe. Which questions help you judge the claim? (select all that apply)
Medium
- AWho carried out the research and who paid for it?
- BWas the work repeated by independent scientists?
- CHow many samples or trials did the evidence come from?
- DDoes the headline use exciting words?
- EIs the crop's advert popular on social media?
30.Which is a possible benefit of crops that make their own insect-killing protein?
Medium
- AThe crop can never be damaged by any pest
- BThe crop no longer needs water
- CFarmers may need to spray less insecticide
- DThe crop grows without soil
31.Which is a possible environmental risk of using the same herbicide repeatedly on herbicide-tolerant crops?
Medium
- AThe crop plants themselves become poisonous to humans
- BWeeds may evolve resistance to the herbicide
- CThe soil slowly turns into a layer of pure water
- DThe herbicide changes into a harmless fertiliser
32.Science alone can settle whether it is right to change the genes of an organism.
Medium
True or false?
33.Match each product to its purpose.
Medium
- Bt maize
- Golden Rice
- Bacterial insulin
- Tissue-culture plantlets
- Treats diabetes
- Provides a source of β-carotene
- Produces many identical plants
- Resists certain insect pests
34.Put the steps of making a clone by nuclear transfer in order.
Medium
- Put the body cell nucleus into the empty egg cell
- Place the embryo in a surrogate mother
- Take a body cell from the animal to be copied
- Give a small electric shock so the egg starts to divide
- Remove the nucleus from an unfertilised egg cell
35.A grower makes 500 plants by tissue culture from one parent plant. A new disease then kills nearly all of them. What is the best explanation?
Medium
- AThe plants all have different alleles from each other, so the disease spreads
- BTissue culture always makes plants weaker than plants grown from seed
- CThe disease can only attack plants that were made using mitosis
- DThe plants are clones, so none has a different chance of resisting the disease
36.A breeder wants cows that make more milk, using only the cow species. Which method is being described?
Medium
- AUsing a restriction enzyme to cut a plasmid for bacteria
- BMaking a recombinant plasmid to put into a bacterial cell
- CSelective breeding of the best milk producers over many generations
- DGrowing identical plantlets from the root tips of cows
37.Complete the sentence.
Medium
In selective breeding, individuals with the desired features are chosen to ____ together.
38.A genetically modified bacterium divides every 20 minutes. Starting from one cell, and assuming none die and food never runs out, how many bacteria are there after 2 hours?
Medium
39.In a test of leaf discs from GM maize and ordinary maize fed to caterpillars, what is the independent variable?
Medium
- AThe area of leaf eaten
- BWhether the maize is GM or not
- CThe number of caterpillars in each dish
- DThe temperature of the room
40.In the same leaf disc test, which factor should be kept the same in every dish?
Medium
- AThe number and age of the caterpillars
- BThe type of maize used in each dish
- CThe result that the experimenter expects
- DThe area of leaf that the caterpillars eat
41.
One company trial compared the yield of GM and non-GM maize at four farms (invented data for this question).
Farm GM yield (tonnes per hectare) Non-GM yield (tonnes per hectare)
A 9.2 8.1
B 8.8 8.5
C 7.9 8.0
D 9.5 8.2
Which conclusion is best supported by these data?
Hard
- AGM maize gives a higher yield on every farm everywhere in the world
- BGM maize gives a lower yield than non-GM maize on these farms
- CGM maize gave the higher yield at three of the four farms, but four farms is a small sample
- DThe data prove that GM maize is completely safe for everyone to eat
- EFarm C shows that GM maize can never work in any place
42.Use the same four-farm trial (GM yields 9.2, 8.8, 7.9 and 9.5; non-GM yields 8.1, 8.5, 8.0 and 8.2 tonnes per hectare). What is the mean yield of the GM maize minus the mean yield of the non-GM maize?
Hard
43.The maker of the GM seed paid for the four-farm trial. What is the most reasonable response from someone reading the results?
Hard
- ALook for the same result from independent researchers using more farms
- BIgnore the data completely because companies never tell the truth
- CAccept the data fully because the company is an expert in seeds
- DDecide the result must be wrong because it is a positive result
- EReject the trial because maize is not an animal species
44.A scientist cuts a human gene with restriction enzyme X, but cuts the plasmid with enzyme Y, which leaves different sticky ends. What is the most likely outcome?
Hard
- AThe gene will join the plasmid more strongly than usual
- BThe pieces will not join easily because the sticky ends do not match
- CDNA ligase will cut the plasmid again into smaller pieces
- DThe bacteria will make a different protein from the same gene
45.Which of these statements is a value judgement rather than a scientific claim?
Hard
- ABt maize makes a protein that is toxic to some caterpillars
- BInsulin from bacteria has the same amino acid sequence as human insulin
- CIt is wrong to change the genes of any living organism
- DWeeds can evolve resistance to a herbicide that is used repeatedly
46.Evaluate the use of GM crops. Give one possible benefit, one possible risk, and say what evidence you would want before deciding.
Hard
47.Compare selective breeding with genetic engineering.
Hard
48.Explain the roles of a restriction enzyme and DNA ligase in making a recombinant plasmid.
Hard
49.Which of these would make evidence that a GM crop reduces insecticide use more reliable? (select all that apply)
Hard
- ARecording the number of insecticide sprays on every field in the study
- BComparing with non-GM fields nearby in the same conditions
- CRepeating the study across several farms and years
- DAsking only farmers who already like the crop
- EUsing the seed company's advert as the data
50.Two clones made from the same parent plant can never differ in any feature.
Hard
True or false?
51.A farmer plants thousands of clones of one apple variety. Explain one advantage and one disadvantage of this.
Hard

Resumos de revisão

## The big idea - **Genetic engineering** moves a gene into another organism. It changes one part of a living **system**, so we must weigh the **consequences** (**Fairness and development**). ## Selective breeding or genetic engineering - **Selective breeding:** slow, uses existing variation in one species. - **Genetic engineering:** fast, can use a gene from another species. ## The steps - Cut out the gene with a **restriction enzyme** (sticky ends). - Cut a **plasmid** with the same enzyme. - Join with **DNA ligase** to make a **recombinant plasmid**. - Put it into **bacteria** and grow them. The genetic code is almost universal. ## Uses - **Human insulin** from bacteria. - **Bt maize** (insect resistance) and **Golden Rice** (beta-carotene). ## Cloning - **Tissue culture** makes identical plants. **Nuclear transfer** made Dolly. - Clones share alleles: **low variation**, so a disease can harm them all. ## Evaluating - Benefits: medicines, less crop loss. Concerns: gene spread, resistant weeds, seed cost. - **Evidence** informs, **values** decide. Ask who did the study, how large it was, and whether it was repeated.

Genetic engineering: Transferring a gene from one organism into another so that it has a new feature.
Genetically modified (GM): Describes an organism whose genes have been changed using genetic engineering.
Selective breeding: Choosing parents with desired features and breeding them over many generations.
Restriction enzyme: An enzyme that cuts DNA at a specific base sequence, often leaving sticky ends.
Sticky ends: Short single-stranded ends of cut DNA that can pair with complementary ends.
DNA ligase: An enzyme that joins pieces of DNA together.
Vector: A carrier, such as a plasmid, that takes a gene into a host cell.
Plasmid: A small ring of DNA found in bacteria, often used as a vector.
Recombinant plasmid: A plasmid that contains DNA from two different sources.
Clone: An organism genetically identical to its parent.
Tissue culture: Growing many identical plants from small pieces of tissue on a nutrient jelly.
Nuclear transfer: Putting a body-cell nucleus into an egg cell whose nucleus has been removed.
Value judgement: A view about what is right or wrong, rather than a claim that evidence can test.

Flashcards

What is genetic engineering?

Moving a gene from one organism into another so that it has a new feature.

What is selective breeding?

Choosing parents with useful features and breeding them over many generations.

Give two differences between selective breeding and genetic engineering.

Genetic engineering is faster and can use genes from other species. Selective breeding is slow and uses only existing variation.

What does a restriction enzyme do?

Cuts DNA at a specific base sequence, often leaving sticky ends.

What does DNA ligase do?

Joins pieces of DNA together, for example a gene into a plasmid.

What is a vector?

A carrier, such as a plasmid, that takes a gene into a host cell.

Why cut the gene and plasmid with the same enzyme?

They get complementary sticky ends that pair up.

What is a recombinant plasmid?

A plasmid containing DNA from two different sources.

Why can bacteria make human proteins?

The genetic code is almost the same in all organisms.

Why are bacteria good host cells?

They divide quickly, so one modified cell soon becomes millions.

How is human insulin made today?

By bacteria carrying the human insulin gene, grown in large tanks.

What is the Bt gene used for?

To make crops produce a protein that is toxic to certain insect pests.

What is Golden Rice?

Rice modified to make β-carotene, which the body turns into vitamin A.

What is a clone?

An organism genetically identical to its parent.

How does plant tissue culture work?

Cells from shoot or root tips grow on nutrient jelly into many identical plantlets.

How was Dolly the sheep made?

A body-cell nucleus was put into an egg cell with its nucleus removed, then the embryo was placed in a surrogate.

Why can a crop of clones be at risk?

They share the same alleles, so one disease can harm them all.

What is the difference between evidence and a value judgement?

Evidence can be tested. A value judgement is a view about what is right or acceptable.

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Farm	GM yield (tonnes per hectare)	Non-GM yield (tonnes per hectare)
A	9.2	8.1
B	8.8	8.5
C	7.9	8.0
D	9.5	8.2