Slide on the topic, gene technology (genetic engineering) for IGCSE Biology.

1. 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
genes(markers)
• cloning the bacteria and harvesting the human insulin;
(b) explain the advantages of treating diabetics with human insulin
produced by gene technology

2. Defination of terms
Chromosome
DNA
Gene

3. DNA (DeoxyriboNucleic Acid)
-DNA is the genetic material of a cell.
- It’s found in the nucleus.
-It is organized into thread like
structures called chromosomes.

4. Structure of DNA
- Made up of small units called nucleotides

5. • Structure of nucleotide
There are four organic bases
- Adenine (A)
- Guanine(G)
- Cytosine (C)
- Thymine (T)

6. Nucleotides form a strand

7. - 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
A-T
C-G.
- These are called complementary
base pairs.

9. Gene
- This is a section of DNA that codes for a
protein.
- The sequence of bases on DNA
determine the type and order of amino
acids in a protein.

10. • Genetic modification is also known as
genetic engineering.
• Genes from one organism are transferred to
the set of genes (the genome) of another
unrelated organism.
• 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
organism.

11. • 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
• Vector
• Either a plasmid/bacterium or virus, it’s used to carry
the desired gene into the organism to be genetically
modified.
• Note: after inserting the new gene into a plasmid,
the plasmid is now called recombinant DNA.

12. Structure of a bacterium

13. General summary of the process of
genetic modification
Genetic modification of bacteria to
produce insulin

15. • 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.

16. 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
hazards, too.
• The economic advantages may be out-
weighed by environmental and ethical
drawbacks or dangers.

17. Questions
• The diagram below shows part of a DNA
molecule. It consists of two strands linked by a
series of paired bases.

18. (a) (i) The bases in DNA are adenine (A),
cytosine (C), guanine (G) and thymine
(T).
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
‘double helix’.

19. (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
species?
(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.