Download Gene Technology – Revision Pack (B6)

Gene Technology – Revision Pack (B6)
Principles of Genetic Engineering:
The process of genetic engineering involves transferring a gene from one organism
to another. The organism which receives the new gene is known as a transgenic
organism.
There are a number of
steps taken in genetic
engineering:
STEP 1 – the desired
characteristic is identified
and removed
STEP 2 – DNA from another
organism is cut open
STEP 3 – the new gene is
inserted into the DNA
To cut and insert the DNA enzymes are used.
STEP 4 – you must check
that the gene works in the
transgenic organism
Transgenic organisms can often be cloned to produce identical copies. The above
example uses bacteria which produce asexually.
The process of genetic engineering ONLY works because the genetic code is
universal. This means that the genes from one organism will produce the same
protein in another organism.
Restriction enzymes are used to cut open the DNA. They leave several unpaired
bases (single strands) on the cut end. This acts as a ‘sticky end’.
Ligase enzymes will join DNA strands because the ‘sticky’ ends on each cut section
of DNA can join by complementary base pairing (A-T, C-G).
Genetic Engineering Bacteria:
Bacteria can be used in genetic engineering to produce human insulin; this happens
via the following steps:
STEP 1 – cut the gene for producing human insulin out of human DNA
STEP 2 – cut open a loop of bacterial DNA
Gene Technology – Revision Pack (B6)
STEP 3 – insert the insulin gene into the loop
STEP 4 – insert the loop into the bacterium
Many copies of the bacteria are cultured by cloning and large quantities of insulin
are made.
The loops of DNA used are called plasmids. These are found in the cytoplasm of the
bacteria and due to the fact that they are taken up from bacteria means they can
be used as vectors for genes.
Not all of the bacteria will take up a plasmid, so to work out which ones
have/haven’t, scientists use an assaying technique:
STEP 1 – scientists add genes that make the bacteria resistant to antibiotics
STEP 2 – the bacteria are then grown on an agar containing the antibiotic
STEP 3 – scientists ONLY choose the bacteria that survive (that are resistant to the
antibiotic) because they have taken up the antibiotic plasmid, and will have taken
up the insulin plasmid
DNA Fingerprints:
DNA ‘fingerprints’ can be produced to identify
individuals. They can be stored to identify people who
commit crimes and prove the innocence of others.
However, some people disagree with storing this
information because it could be used to assess the
possibility of someone getting a life-limiting disease –
this could be used as a reason to withhold life
insurance.
To produce a DNA ‘fingerprint’, the following steps are
used:
STEP 1 – DNA is extracted from a sample (e.g. blood)
STEP 2 – the DNA is cut up or fragmented using restriction enzymes
STEP 3 – the fragments are separated using electrophoresis
STEP 4 – the fragments are then made visible using a radioactive probe
In the image above, you can clearly see that suspect two was present at the crime
scene, and it is this sort of information which is used by police detectives and
forensic examiners to prove guilt (suspect 2) and innocence (suspects 1 and 3).
Gene Technology – Revision Pack (B6)
Past Papers:
PPQ(1):
PPQ(2):
Gene Technology – Revision Pack (B6)
PPQ(3):
Gene Technology – Revision Pack (B6)
PPQ(4):
Continued on next page...
Gene Technology – Revision Pack (B6)
Gene Technology – Revision Pack (B6)
Mark Schemes:
PPQ(1):
PPQ(2):
PPQ(3):
PPQ(4):