Genetic engineering is a technique used to deliberately modify a specific characteristic of an organism by transferring a gene from one organism into another.

Genetically modified organism (GMO)

An organism that contains recombinant DNA , having had a gene from another organism transferred into it so that a desired characteristic is expressed.

Which type of enzyme is used to remove a desired gene from an organism's genome?

Restriction enzymes (restriction endonucleases) are used to cut out the desired gene.

Why is the polymerase chain reaction (PCR) used when producing genetically modified micro-organisms?

PCR is used to make many copies of the desired gene.

Which enzyme catalyses the joining of a desired gene to a plasmid vector?

DNA ligase catalyses the joining of the gene to the plasmid.

Genetically modified micro-organisms are grown in large containing nutrients, enabling them to multiply and produce large quantities of the new protein.

Genetically modified micro-organisms are grown in large fermenters containing nutrients, enabling them to multiply and produce large quantities of the new protein.

Name two medicinal proteins produced by genetically modified bacteria.

Human insulin and human blood clotting factors .

How can bacteria be used to introduce a desired gene into plant cells?

The bacterium acts as a vector , infecting the plant cells and introducing the gene into the plant DNA.

Other than using bacteria, how can a desired gene be introduced into plant cells?

Using a gene gun ; tiny pellets coated with the desired DNA are fired into the plant cells.

How are drugs produced using genetically modified animals?

The desired gene is injected into the nucleus of a zygote , which is implanted into a surrogate; the protein can then be purified from the animal's milk .

True or False? Genetically modified plants can be eaten to deliver a drug, such as a cholera vaccine.

True. The protein can be purified from the plant tissues, or the plant can be eaten to deliver the drug.

In a genetically modified animal, which cells contain a copy of the gene coding for the desired protein?

Every cell of the animal contains a copy of the gene.

DNA that has been artificially altered by combining lengths of nucleotides from different sources , typically different species.

Restriction endonuclease

An enzyme that cuts DNA at a specific base sequence known as a restriction site .

The exposed, single-stranded sequences of bases left when a restriction endonuclease cuts the DNA backbone unevenly.

Why does the universal nature of the genetic code allow recombinant DNA to be made?

The same codons code for the same amino acids in all organisms, so genetic information is transferable between species .

What is a restriction site?

A specific sequence of bases that a particular restriction endonuclease binds to and cuts.

Why are sticky ends useful when making recombinant DNA?

They can form hydrogen bonds with complementary sticky ends on DNA cut by the same restriction endonuclease .

Which enzyme joins a desired gene into a vector, and which bonds does it catalyse?

DNA ligase catalyses the formation of phosphodiester bonds in the sugar-phosphate backbone.

To insert a desired gene, the vector DNA must be cut with the restriction endonuclease as the gene, leaving complementary sticky ends.

To insert a desired gene, the vector DNA must be cut with the same restriction endonuclease as the gene, leaving complementary sticky ends.

List the four stages involved in producing a transgenic organism.

Identification , isolation , multiplication and transfer of the desired gene.

Other than cutting it out with restriction endonucleases, how can a desired gene be isolated?

Using reverse transcriptase to convert mRNA into complementary DNA (cDNA) .

A plasmid that has had a desired gene inserted into it using DNA ligase.

True or False? Restriction endonucleases cut the sugar-phosphate backbone of DNA in an even, straight line.

False. They cut the backbone unevenly , leaving single-stranded sticky ends.

The process by which recombinant plasmid DNA is transferred into other cells , usually bacteria.

A means of carrying DNA into a cell , e.g. a plasmid, virus, liposome, gene gun or microinjection.

A gene, such as one for antibiotic resistance , used to identify cells that have taken up the desired gene.

Name four types of vector used to transfer recombinant DNA into cells.

Plasmids , viruses , liposomes and gene guns (microinjection is also used).

How are marker genes used to identify transformed bacteria?

Only transformed cells take up the marker gene, so, for example, they survive treatment with a specific antibiotic .

Why must transferred DNA be incorporated into the cell's genetic material?

So that it can be transcribed and translated to express the desired protein.

The success rate for transferred genes entering the nucleus of a eukaryotic cell is currently very , which is a barrier to gene therapy.

The success rate for transferred genes entering the nucleus of a eukaryotic cell is currently very low , which is a barrier to gene therapy.

How can bacteria be made to take up plasmids during transformation?

By bathing them in ice-cold calcium chloride solution then briefly heating, or by electroporation (a small electric shock).

Why are viruses useful as vectors?

They naturally insert their DNA into host cells , helping transferred DNA reach the nucleus .

What is one disadvantage of using viral vectors?

They can sometimes initiate an immune response .

How do liposomes act as vectors?

These phospholipid vesicles fuse with the cell surface membrane to carry DNA into the cell.

True or False? Microinjection uses a fine glass micropipette to transfer DNA into a cell.

True. It is commonly used to transfer genetic material into animal cells to create transgenic animals.

A small piece of glass, plastic or silicon with DNA probes attached in a grid, used to identify active genes .

A gene that is expressed ; mRNA is transcribed from it and translated into a polypeptide.

A short, single-stranded length of DNA carrying an identifiable label that binds to complementary sequences in a sample.

Why is mRNA, rather than DNA, collected when identifying active genes?

Only active genes are transcribed into mRNA, so collecting mRNA reveals which genes are being expressed.

Which enzyme converts mRNA into cDNA for use on a microarray?

Reverse transcriptase converts mRNA into complementary DNA (cDNA) .

On a microarray, what does it show if a gene spot fluoresces yellow?

The gene is being expressed in equal quantities in the reference and unknown samples.

If the reference sample fluoresces green and the unknown red, what does an overall green spot indicate?

The gene is being expressed more in the reference individual than in the unknown sample.

What does a lack of fluorescence at a gene spot indicate?

The gene is not being expressed at all.

After the labelled samples hybridise with the probes, any DNA that did not hybridise is off before the microarray is scanned.

After the labelled samples hybridise with the probes, any DNA that did not hybridise is washed off before the microarray is scanned.

Give one medical use of microarrays.

Diagnosis and treatment , e.g. identifying harmful mutations or genes linked to certain cancers.

Why is a known reference sample used on a microarray?

It provides a control for comparison, e.g. genetic material from an individual known to have a particular mutation.

True or False? Microarrays can only analyse one gene sample at a time.

False. They can identify active genes in thousands of gene samples simultaneously.

An interdisciplinary science that combines biology , computer technology and statistics to collect, organise, store and analyse biological data .

Why is bioinformatics needed?

New technologies such as microarrays and sequencing generate enormous quantities of data that must be analysed.

Give two examples of biological data generated by new DNA technologies.

Genome sequences and information on gene expression (also amino acid sequences of proteins).

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Gene Technology (Edexcel International A Level (IAL) Biology): Flashcards

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Genetic engineering

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Genetic engineering
Genetic engineering is a technique used to deliberately modify a specific characteristic of an organism by transferring a gene from one organism into another.
Genetically modified organism (GMO)
An organism that contains recombinant DNA, having had a gene from another organism transferred into it so that a desired characteristic is expressed.
Which type of enzyme is used to remove a desired gene from an organism's genome?
Restriction enzymes (restriction endonucleases) are used to cut out the desired gene.
Why is the polymerase chain reaction (PCR) used when producing genetically modified micro-organisms?
PCR is used to make many copies of the desired gene.
Which enzyme catalyses the joining of a desired gene to a plasmid vector?
DNA ligase catalyses the joining of the gene to the plasmid.
Genetically modified micro-organisms are grown in large containing nutrients, enabling them to multiply and produce large quantities of the new protein.
Genetically modified micro-organisms are grown in large fermenters containing nutrients, enabling them to multiply and produce large quantities of the new protein.
Name two medicinal proteins produced by genetically modified bacteria.
Human insulin and human blood clotting factors.
How can bacteria be used to introduce a desired gene into plant cells?
The bacterium acts as a vector, infecting the plant cells and introducing the gene into the plant DNA.
Other than using bacteria, how can a desired gene be introduced into plant cells?
Using a gene gun; tiny pellets coated with the desired DNA are fired into the plant cells.
How are drugs produced using genetically modified animals?
The desired gene is injected into the nucleus of a zygote, which is implanted into a surrogate; the protein can then be purified from the animal's milk.
True or False?
Genetically modified plants can be eaten to deliver a drug, such as a cholera vaccine.
True.
The protein can be purified from the plant tissues, or the plant can be eaten to deliver the drug.
In a genetically modified animal, which cells contain a copy of the gene coding for the desired protein?
Every cell of the animal contains a copy of the gene.
Recombinant DNA
DNA that has been artificially altered by combining lengths of nucleotides from different sources, typically different species.
Restriction endonuclease
An enzyme that cuts DNA at a specific base sequence known as a restriction site.
Sticky ends
The exposed, single-stranded sequences of bases left when a restriction endonuclease cuts the DNA backbone unevenly.
Why does the universal nature of the genetic code allow recombinant DNA to be made?
The same codons code for the same amino acids in all organisms, so genetic information is transferable between species.
What is a restriction site?
A specific sequence of bases that a particular restriction endonuclease binds to and cuts.
Why are sticky ends useful when making recombinant DNA?
They can form hydrogen bonds with complementary sticky ends on DNA cut by the same restriction endonuclease.
Which enzyme joins a desired gene into a vector, and which bonds does it catalyse?
DNA ligase catalyses the formation of phosphodiester bonds in the sugar-phosphate backbone.
To insert a desired gene, the vector DNA must be cut with the restriction endonuclease as the gene, leaving complementary sticky ends.
To insert a desired gene, the vector DNA must be cut with the same restriction endonuclease as the gene, leaving complementary sticky ends.
List the four stages involved in producing a transgenic organism.
Identification, isolation, multiplication and transfer of the desired gene.
Other than cutting it out with restriction endonucleases, how can a desired gene be isolated?
Using reverse transcriptase to convert mRNA into complementary DNA (cDNA).
Recombinant plasmid
A plasmid that has had a desired gene inserted into it using DNA ligase.
True or False?
Restriction endonucleases cut the sugar-phosphate backbone of DNA in an even, straight line.
False.
They cut the backbone unevenly, leaving single-stranded sticky ends.
Transformation
The process by which recombinant plasmid DNA is transferred into other cells, usually bacteria.
Vector
A means of carrying DNA into a cell, e.g. a plasmid, virus, liposome, gene gun or microinjection.
Marker gene
A gene, such as one for antibiotic resistance, used to identify cells that have taken up the desired gene.
Name four types of vector used to transfer recombinant DNA into cells.
Plasmids, viruses, liposomes and gene guns (microinjection is also used).
How are marker genes used to identify transformed bacteria?
Only transformed cells take up the marker gene, so, for example, they survive treatment with a specific antibiotic.
Why must transferred DNA be incorporated into the cell's genetic material?
So that it can be transcribed and translated to express the desired protein.
The success rate for transferred genes entering the nucleus of a eukaryotic cell is currently very , which is a barrier to gene therapy.
The success rate for transferred genes entering the nucleus of a eukaryotic cell is currently very low, which is a barrier to gene therapy.
How can bacteria be made to take up plasmids during transformation?
By bathing them in ice-cold calcium chloride solution then briefly heating, or by electroporation (a small electric shock).
Why are viruses useful as vectors?
They naturally insert their DNA into host cells, helping transferred DNA reach the nucleus.
What is one disadvantage of using viral vectors?
They can sometimes initiate an immune response.
How do liposomes act as vectors?
These phospholipid vesicles fuse with the cell surface membrane to carry DNA into the cell.
True or False?
Microinjection uses a fine glass micropipette to transfer DNA into a cell.
True.
It is commonly used to transfer genetic material into animal cells to create transgenic animals.
Microarray
A small piece of glass, plastic or silicon with DNA probes attached in a grid, used to identify active genes.
Active gene
A gene that is expressed; mRNA is transcribed from it and translated into a polypeptide.
DNA probe
A short, single-stranded length of DNA carrying an identifiable label that binds to complementary sequences in a sample.
Why is mRNA, rather than DNA, collected when identifying active genes?
Only active genes are transcribed into mRNA, so collecting mRNA reveals which genes are being expressed.
Which enzyme converts mRNA into cDNA for use on a microarray?
Reverse transcriptase converts mRNA into complementary DNA (cDNA).
On a microarray, what does it show if a gene spot fluoresces yellow?
The gene is being expressed in equal quantities in the reference and unknown samples.
If the reference sample fluoresces green and the unknown red, what does an overall green spot indicate?
The gene is being expressed more in the reference individual than in the unknown sample.
What does a lack of fluorescence at a gene spot indicate?
The gene is not being expressed at all.
After the labelled samples hybridise with the probes, any DNA that did not hybridise is off before the microarray is scanned.
After the labelled samples hybridise with the probes, any DNA that did not hybridise is washed off before the microarray is scanned.
Give one medical use of microarrays.
Diagnosis and treatment, e.g. identifying harmful mutations or genes linked to certain cancers.
Why is a known reference sample used on a microarray?
It provides a control for comparison, e.g. genetic material from an individual known to have a particular mutation.
True or False?
Microarrays can only analyse one gene sample at a time.
False.
They can identify active genes in thousands of gene samples simultaneously.
Bioinformatics
An interdisciplinary science that combines biology, computer technology and statistics to collect, organise, store and analyse biological data.
Why is bioinformatics needed?
New technologies such as microarrays and sequencing generate enormous quantities of data that must be analysed.
Give two examples of biological data generated by new DNA technologies.
Genome sequences and information on gene expression (also amino acid sequences of proteins).
What kind of information is stored in the large databases created by bioinformatics?
Information such as gene sequences and the amino acid sequences of proteins.
Why is it useful that bioinformatics databases are available online?
Research groups worldwide can contribute to and analyse central databases and raise queries.
How can bioinformatics be used to study evolutionary relationships?
The DNA sequences of different species can be compared to establish evolutionary relationships.
How does bioinformatics speed up drug development?
New drug candidates can be identified quickly by scanning libraries of molecules, and tested safely using computer simulations.
Data from microarrays and gene sequencing can be analysed to develop medical treatments tailored to individuals.
Data from microarrays and gene sequencing can be analysed to develop personalised medical treatments tailored to individuals.
How can bioinformatics support genetic testing?
New types of genetic testing can be developed to identify genetic diseases.
How does bioinformatics help in producing recombinant DNA?
It helps identify desired genes and the best site to insert new genes into a GMO's genome.
Biological database
A large, often online, store of biological data such as gene and amino acid sequences that scientists can analyse.
True or False?
Bioinformatics uses only biological knowledge, with no input from computer technology or statistics.
False.
It combines biology, computer technology and statistics.
Genetically modified organism (GMO)
An organism whose genome has been altered by genetic engineering to introduce a desired characteristic.
Why do many people have concerns about GMOs?
There is concern about the potential impacts of changing organisms' genes and the ethics of modifying animals.
Why are concerns about GMOs often greatest for crop plants?
Because the crops are often destined for human consumption.
Give one agricultural benefit of genetically modifying crop plants.
Crops can be given pest resistance or higher yields, reducing the need for chemical pesticides.
How can GMOs benefit human health?
They can produce medicines such as insulin cheaply and in large quantities, and crops with improved nutritional value.
How might GM crops improve nutrition in some regions?
Crops can be engineered to contain added nutrients, e.g. vitamin A, helping to reduce deficiency diseases.
What is one environmental risk of growing GM crops?
Introduced genes may spread to wild populations (gene flow), e.g. creating herbicide-resistant weeds.
How might GM crops reduce biodiversity?
Widespread planting of a single modified variety encourages monocultures, reducing biodiversity.
Genes introduced into GM crops could be transferred to non-target organisms, potentially harming populations such as beneficial insects.
Genes introduced into GM crops could be transferred to non-target organisms, potentially harming wild populations such as beneficial insects.
Give one economic concern associated with GM crops.
Companies can patent GM seeds, making farmers dependent on buying them each year.
Give one ethical concern about genetically modifying animals.
It raises concerns about animal welfare and whether it is right to alter animals for human benefit.
True or False?
Genetic modification of organisms brings only benefits and no risks.
False.
GMOs bring both benefits and risks, which must be weighed against each other.

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