GENE TECHNOLOGY (GENETIC ENGINEERING)
By the end of the topic you must be able to:
describe the steps involved in the production of bacteria capable of
synthesizing human insulin:
• identifying the human insulin gene
• isolating mRNA and making cDNA using reverse transcriptase
• cloning the DNA using DNA polymerase
• inserting the DNA into a plasmid vector using restriction enzymes
and DNA ligase
• inserting the plasmid vector into the host bacterium
• identifying genetically modified bacteria using antibiotic resistance
• cloning the bacteria and harvesting the human insulin;
(b) explain the advantages of treating diabetics with human insulin
produced by gene technology
- DNA has two strands that coil around
each other like a twisted ladder. This is
called a double helix.
- Bases on one strand pair up with
bases on the other strand
- These are called complementary
- This is a section of DNA that codes for a
- The sequence of bases on DNA
determine the type and order of amino
acids in a protein.
• Genetic modification is also known as
• Genes from one organism are transferred to
the set of genes (the genome) of another
• Transgenic- means the transfer of genes from
one organism to another of a different species
• An organism that contains a gene from
another species is called a transgenic
• Enzymes used in genetic modification
• Restriction endonuclease
• An enzyme that cuts DNA at specific sites.
• The two ends of the cut DNA have a natural affinity
and are called sticky ends.
• DNA ligase
• An enzyme used to join pieces of DNA
• Either a plasmid/bacterium or virus, it’s used to carry
the desired gene into the organism to be genetically
• Note: after inserting the new gene into a plasmid,
the plasmid is now called recombinant DNA.
General summary of the process of
Genetic modification of bacteria to
• Note: The outcome of genetic modification
are new varieties of organisms, mostly but not
exclusively of micro-organisms.
• Micro-organisms are preferred simply because
they are easier to modify.
• Gene technology has important applications in
biotechnology, medicinal drug production
(pharmaceuticals industry), gene therapy,
agriculture and horticulture.
This technique is used to manufacture
• Enzymes for washing powders, food industry.
• Human growth hormone.
• Human vaccines
• Bovine somatotropin (BST) used to increase
milk yield and meat production.
• Genetic engineering generates many potential
benefits for humans, but there are potential
• The economic advantages may be out-
weighed by environmental and ethical
drawbacks or dangers.
• The diagram below shows part of a DNA
molecule. It consists of two strands linked by a
series of paired bases.
(a) (i) The bases in DNA are adenine (A),
cytosine (C), guanine (G) and thymine
Complete the diagram above by writing in
the correct base to complete each pair.
(ii) The DNA molecule is known as a double
helix. Explain what is meant by the term
(b) Genetic modification (genetic engineering) uses
enzymes to cut and join sections of DNA.
(i) Name the enzyme used to cut DNA at a specific site.
(ii) Name the enzyme used to join two sections of DNA.
(iii) What name is given to an organism that has been
genetically modified to contain DNA from a different
(c) (i) Name one human hormone that is produced by
genetically modified bacteria.
(ii) Give one advantage of using genetically modified
bacteria to produce this hormone.