19 Genetic technology
19.1 Principles of genetic 4) the gene is inserted into a vector (e.g., plasmids,
technology viruses, liposomes)
5) the vector delivers the gene to the cells of the
a) Recombinant DNA organism
The aim of genetic engineering is to remove a gene (or 6) cells expressing the new genes are identified (using a
genes) from one organism and transfer it into another so marker) and are then cloned
that the gene is expressed in the new host.
This DNA that has been altered is called recombinant c) Polymerase chain reaction (PCR)
DNA (rDNA). PCR is an artificial method of rapidly replicating DNA
under laboratory conditions, producing large quantities.
• recombinant DNA (rDNA) – DNA made by joining
pieces from two or more different sources Each PCR reaction requires –
• transgenic organism / genetically modified organism 1) DNA (or RNA) sample to be amplified
(GMO) – organism that expresses the genes that have 2) primers
been attained from another organism because of 3) free nucleotides to be used in the construction of the
rDNA DNA or RNA strands
4) buffer solutions to provide the optimum pH for the
reactions to occur in
b) Overview of gene transfer 5) DNA polymerase
Taq polymerase
Taq polymerase is a heat-stable form of DNA polymerase
extracted from a thermophilic bacterium (Thermus
aquaticus) and is used in PCR
Features of Taq polymerase that enable it to be used in
PCR
1) it’s not destroyed in the denaturation step, so it
doesn’t have to be replaced each cycle
2) its high optimum temperature (72°C) means the
temperature for the elongation step does not have to
be dropped below that of the annealing process, so
efficiency is maximised
Primers
• Taq polymerase can only make DNA if it’s given a
primer
• primers are short sequences of single-stranded DNA
Image: http://conceptreelibrary.com/ that have base sequences complimentary to the 3’
The following steps are always necessary for the transfer end of the DNA or RNA being copied
of a genes into another organism (can be of the same or • they define the region that is to be amplified by
different species as the source) – identifying to the DNA polymerase the starting point
for DNA synthesis
1) the desired gene is identified
2) the desired gene is isolated for it to be extracted
- the gene can be extracted by cutting it from a
chromosome using enzymes called restriction
endonucleases
- the enzyme reverse transcriptase can also be
used to make a single strand of complementary
DNA (cDNA) from mRNA
- the gene can also be also be created artificially
using nucleotides
3) the gene is multiplied using polymerase chain reaction
(PCR) Image: https://www.khanacademy.org/
1 www.alevel-notes.weebly.com
, • when the primers are bound to the template, they
can be extended by the polymerase and the region
that lies between them will get copied
PCR can be summarised in 3 steps, and they all require
different temperatures –
1) denaturation (95°C) – the double stranded DNA is
heated to 95°C which breaks the hydrogen bonds
Image: https://www.khanacademy.org/
and separates the DNA strands
2) annealing (65°C) – the temperature is decreased to Electrophoresis of proteins
65°C so that primers can bind to their • gel electrophoresis of proteins is used to separate
complementary sequences on the single-stranded polypeptides produced by different alleles of the
template DNA same gene e.g., the haemoglobin variants (⍺-globin,
3) elongation (72°C) – the temperature is increased to β-globin, and the sickle cell anaemia variant of β-
72°C as this is the optimum temperature for Taq globin)
polymerase
• they can be separated as the different polypeptides
- Taq polymerase builds the complimentary strand have different net charges
of DNA by extending the primer and produces
• the charge on proteins is dependent on the
new identical double-stranded DNA
ionisation of R groups of amino acids
• the charge of the R groups depends on the pH
• therefore, buffer solutions are used during the
separation of proteins to keep the pH constant
• once electrophoresis has been performed, the
results can be compared against known industry
standards (e.g., from a bioinformatics database)
Image: https://www.bio-rad.com/
Electrophoresis of DNA
Image: https://www.khanacademy.org/
Electrophoresis of DNA is used to separate DNA
fragments for DNA fingerprinting to investigate crime
d) Gel electrophoresis scenes (part of 19.2g) or to analyse genes.
Gel electrophoresis is a technique used for separating These steps are for the electrophoresis of DNA for
and analysing nucleic acids or proteins based on their genetic profiling (fingerprinting) –
size and electrical charge.
1) DNA quantity is increased using PCR
1) sample is placed in well at the end of the gel 2) restriction enzymes cut the DNA into fragments
2) electric field is passed through the gel (different restriction enzymes cut the DNA at
3) negatively charged molecules are attracted to the different base sequences, so enzymes that will cut
anode close to the VNTR regions need to be used)
4) shorter fragments move further in unit time 3) electrophoresis is carried out on the DNA sample
4) fragments separate as DNA is negatively charged
due to the presence of phosphate groups
2 www.alevel-notes.weebly.com
19.1 Principles of genetic 4) the gene is inserted into a vector (e.g., plasmids,
technology viruses, liposomes)
5) the vector delivers the gene to the cells of the
a) Recombinant DNA organism
The aim of genetic engineering is to remove a gene (or 6) cells expressing the new genes are identified (using a
genes) from one organism and transfer it into another so marker) and are then cloned
that the gene is expressed in the new host.
This DNA that has been altered is called recombinant c) Polymerase chain reaction (PCR)
DNA (rDNA). PCR is an artificial method of rapidly replicating DNA
under laboratory conditions, producing large quantities.
• recombinant DNA (rDNA) – DNA made by joining
pieces from two or more different sources Each PCR reaction requires –
• transgenic organism / genetically modified organism 1) DNA (or RNA) sample to be amplified
(GMO) – organism that expresses the genes that have 2) primers
been attained from another organism because of 3) free nucleotides to be used in the construction of the
rDNA DNA or RNA strands
4) buffer solutions to provide the optimum pH for the
reactions to occur in
b) Overview of gene transfer 5) DNA polymerase
Taq polymerase
Taq polymerase is a heat-stable form of DNA polymerase
extracted from a thermophilic bacterium (Thermus
aquaticus) and is used in PCR
Features of Taq polymerase that enable it to be used in
PCR
1) it’s not destroyed in the denaturation step, so it
doesn’t have to be replaced each cycle
2) its high optimum temperature (72°C) means the
temperature for the elongation step does not have to
be dropped below that of the annealing process, so
efficiency is maximised
Primers
• Taq polymerase can only make DNA if it’s given a
primer
• primers are short sequences of single-stranded DNA
Image: http://conceptreelibrary.com/ that have base sequences complimentary to the 3’
The following steps are always necessary for the transfer end of the DNA or RNA being copied
of a genes into another organism (can be of the same or • they define the region that is to be amplified by
different species as the source) – identifying to the DNA polymerase the starting point
for DNA synthesis
1) the desired gene is identified
2) the desired gene is isolated for it to be extracted
- the gene can be extracted by cutting it from a
chromosome using enzymes called restriction
endonucleases
- the enzyme reverse transcriptase can also be
used to make a single strand of complementary
DNA (cDNA) from mRNA
- the gene can also be also be created artificially
using nucleotides
3) the gene is multiplied using polymerase chain reaction
(PCR) Image: https://www.khanacademy.org/
1 www.alevel-notes.weebly.com
, • when the primers are bound to the template, they
can be extended by the polymerase and the region
that lies between them will get copied
PCR can be summarised in 3 steps, and they all require
different temperatures –
1) denaturation (95°C) – the double stranded DNA is
heated to 95°C which breaks the hydrogen bonds
Image: https://www.khanacademy.org/
and separates the DNA strands
2) annealing (65°C) – the temperature is decreased to Electrophoresis of proteins
65°C so that primers can bind to their • gel electrophoresis of proteins is used to separate
complementary sequences on the single-stranded polypeptides produced by different alleles of the
template DNA same gene e.g., the haemoglobin variants (⍺-globin,
3) elongation (72°C) – the temperature is increased to β-globin, and the sickle cell anaemia variant of β-
72°C as this is the optimum temperature for Taq globin)
polymerase
• they can be separated as the different polypeptides
- Taq polymerase builds the complimentary strand have different net charges
of DNA by extending the primer and produces
• the charge on proteins is dependent on the
new identical double-stranded DNA
ionisation of R groups of amino acids
• the charge of the R groups depends on the pH
• therefore, buffer solutions are used during the
separation of proteins to keep the pH constant
• once electrophoresis has been performed, the
results can be compared against known industry
standards (e.g., from a bioinformatics database)
Image: https://www.bio-rad.com/
Electrophoresis of DNA
Image: https://www.khanacademy.org/
Electrophoresis of DNA is used to separate DNA
fragments for DNA fingerprinting to investigate crime
d) Gel electrophoresis scenes (part of 19.2g) or to analyse genes.
Gel electrophoresis is a technique used for separating These steps are for the electrophoresis of DNA for
and analysing nucleic acids or proteins based on their genetic profiling (fingerprinting) –
size and electrical charge.
1) DNA quantity is increased using PCR
1) sample is placed in well at the end of the gel 2) restriction enzymes cut the DNA into fragments
2) electric field is passed through the gel (different restriction enzymes cut the DNA at
3) negatively charged molecules are attracted to the different base sequences, so enzymes that will cut
anode close to the VNTR regions need to be used)
4) shorter fragments move further in unit time 3) electrophoresis is carried out on the DNA sample
4) fragments separate as DNA is negatively charged
due to the presence of phosphate groups
2 www.alevel-notes.weebly.com
