Complete notes for A-Levels BiologyCIE according to syllabus objectives - updated 2025
Biology (9700) notes A-Level - Genetic Technology (CIE)
Principles of Genetic technology
● Recombinant DNA: DNA made by artificially joining together
pieces of DNA from two or more different species.
● Genetic engineering: It is the deliberate manipulation of
genetic material to modify specific characteristics of an
organism, this may involve transferring of a gene into an
A2
organism so that the gene is expressed. (Any procedure in
which the genetic information is changed by altering the base
sequence of a gene or by introducing a gene from another
s
organism).
● Genes transferred into an organism may be extracted from the
am
DNA of a donor organism (using enzymes). Synthesised from
the mRNA of a donor organism (reverse transcriptase to make
a single stranded DNA from mRNA). Synthesised chemically
Ex
from nucleotides (artificially).
● Role of Restriction endonucleases, DNA ligase, plasmids, DNA
polymerase and reverse transcriptase in the transfer of gene
ck
into an organism: Restriction endonucleases → cuts the DNA
strand so that the desired gene can be isolated or inserted
into the vector. DNA ligase → Is used to insert the gene into
ra
the vector. Plasmids → Open plasmid using restriction enzyme,
insert desired gene, seal with ligase, modified plasmid in host
C
cell, cell makes what gene codes for. DNA polymerase → Used
to convert the single stranded DNA into double stranded DNA
molecule of the desired DNA. Reverse transcriptase →
Reverses transcription to produce a single strand
complementary DNA (cDNA) from a mRNA strand with the
code for the desired gene.
CRACK EXAMS A2 1
, Complete notes for A-Levels BiologyCIE according to syllabus objectives - updated 2025
● A promoter is a DNA sequence that controls the expression of
a gene by signalling to begin transcription. When a gene is
transferred into an organism, it may not be expressed properly
if it doesn't have a suitable promoter. Therefore, a promoter
is often transferred along the desired gene to ensure that the
host cell recognizes the gene and expresses it correctly and
efficiently. (The promoter is the region of DNA that
determines which gene will be expressed. (Site where RNA
A2
polymerase binds to begin transcription).
● A marker is a gene that is transferred with the desired gene
to enable it to identify which cells have been successfully
altered and now contain recombinant DNA. The fluorescence is
s
due to the presence of green fluorescent protein (GFP). When
am
the host organism expresses the desired gene it also
expresses the marker gene. The production of fluorescence
can be detected under UV light, confirming that the gene has
Ex
been successfully taken up and is being expressed.
● CRISPR: Using natural defence mechanism bacteria determined
by guide RNA attached to an enzyme. Once cut, scientists can
ck
either insert, delete or replace the faulty DNA with normal
DNA. Gene therapy → treatment of genetic diseases by
altering the person's genotype.
ra
● PCR → DNA profiling (e.g. identification of criminals) (in vitro
method of DNA amplification). It is used to produce large
C
quantities (from small) of specific fragments of DNA/RNA.
● PCR requires: Target DNA or RNA being amplified. Primers
(forward or reverse), these are short sequences of DNA or
RNA being copied. DNA polymerase → enzyme used to build
the new DNA or RNA strand. (Taq polymerase → doesn't
denature at high temperature, its optimum temperature is high
enough to prevent the annealing of the DNA strands that have
CRACK EXAMS A2 2
Biology (9700) notes A-Level - Genetic Technology (CIE)
Principles of Genetic technology
● Recombinant DNA: DNA made by artificially joining together
pieces of DNA from two or more different species.
● Genetic engineering: It is the deliberate manipulation of
genetic material to modify specific characteristics of an
organism, this may involve transferring of a gene into an
A2
organism so that the gene is expressed. (Any procedure in
which the genetic information is changed by altering the base
sequence of a gene or by introducing a gene from another
s
organism).
● Genes transferred into an organism may be extracted from the
am
DNA of a donor organism (using enzymes). Synthesised from
the mRNA of a donor organism (reverse transcriptase to make
a single stranded DNA from mRNA). Synthesised chemically
Ex
from nucleotides (artificially).
● Role of Restriction endonucleases, DNA ligase, plasmids, DNA
polymerase and reverse transcriptase in the transfer of gene
ck
into an organism: Restriction endonucleases → cuts the DNA
strand so that the desired gene can be isolated or inserted
into the vector. DNA ligase → Is used to insert the gene into
ra
the vector. Plasmids → Open plasmid using restriction enzyme,
insert desired gene, seal with ligase, modified plasmid in host
C
cell, cell makes what gene codes for. DNA polymerase → Used
to convert the single stranded DNA into double stranded DNA
molecule of the desired DNA. Reverse transcriptase →
Reverses transcription to produce a single strand
complementary DNA (cDNA) from a mRNA strand with the
code for the desired gene.
CRACK EXAMS A2 1
, Complete notes for A-Levels BiologyCIE according to syllabus objectives - updated 2025
● A promoter is a DNA sequence that controls the expression of
a gene by signalling to begin transcription. When a gene is
transferred into an organism, it may not be expressed properly
if it doesn't have a suitable promoter. Therefore, a promoter
is often transferred along the desired gene to ensure that the
host cell recognizes the gene and expresses it correctly and
efficiently. (The promoter is the region of DNA that
determines which gene will be expressed. (Site where RNA
A2
polymerase binds to begin transcription).
● A marker is a gene that is transferred with the desired gene
to enable it to identify which cells have been successfully
altered and now contain recombinant DNA. The fluorescence is
s
due to the presence of green fluorescent protein (GFP). When
am
the host organism expresses the desired gene it also
expresses the marker gene. The production of fluorescence
can be detected under UV light, confirming that the gene has
Ex
been successfully taken up and is being expressed.
● CRISPR: Using natural defence mechanism bacteria determined
by guide RNA attached to an enzyme. Once cut, scientists can
ck
either insert, delete or replace the faulty DNA with normal
DNA. Gene therapy → treatment of genetic diseases by
altering the person's genotype.
ra
● PCR → DNA profiling (e.g. identification of criminals) (in vitro
method of DNA amplification). It is used to produce large
C
quantities (from small) of specific fragments of DNA/RNA.
● PCR requires: Target DNA or RNA being amplified. Primers
(forward or reverse), these are short sequences of DNA or
RNA being copied. DNA polymerase → enzyme used to build
the new DNA or RNA strand. (Taq polymerase → doesn't
denature at high temperature, its optimum temperature is high
enough to prevent the annealing of the DNA strands that have
CRACK EXAMS A2 2
