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GENE TECHNOLOGY
Studying the genomes of organisms
Genetic Engineering- From The Beginning
 Cohen and Boyer isolated a gene for ribosomal RNA from
the DNA of a frog and inserted it into the DNA of E.coli
bacteria.
 During transcription the bacteria produced frog
rRNA, becoming the first genetically altered
organism.
 The process of manipulating genes for practical
purposes is called genetic engineering.
Why do we use Genetic Engineering?
 Drugs
 Vaccines
 Improving crops
 Animal Farming
 Cloning
Why do we use Genetic Engineering?
 One of the first uses of this technology was for the production of
human insulin.
 What is insulin?
 A protein hormone that controls sugar metabolism.
 Who needs it?
 Diabetics who cannot produce enough insulin.
 Where did they get it?
 Before genetic engineering, insulin was
extracted from the pancreases of slaughtered
cows and pigs and then purified.
 Today, the human insulin gene is cloned
into bacteria so that they produce human insulin.
Words You Should Know to Understand
Genetic Engineering
 Recombinant DNA- DNA made from two or
more different organisms
 Restriction enzymes- enzymes that recognize
and then cut the DNA between specific
nucleotides.
EcoR1 recognition site
CTGAATTCCG
GACTTAAGGC

CTG|AATTCCG
GACTTAA|GGC

Many Restriction Enzymes Exist
What do you use
restriction enzymes for?
Molecular Cloning
Genetic Engineering- Molecular Cloning
 What is molecular cloning?
 A set of experimental methods used to assemble
recombinant DNA molecules and direct their
replication in a host organism, like E. coli.
Genetic Engineering- Molecular Cloning
 Why do scientists use molecular
cloning?
 To make multiple copies of a specific DNA
sequence.
 To make large amounts of specific human proteins
which can be used in medicine.
 To genetically modify a cell.
How does molecular
cloning happen?
Genetic Engineering- Molecular Cloning
 Step 1- Cutting DNA
 The DNA from the organism containing the desired
gene is cut using a restriction enzyme.
 EX:
ATTGCC
TAACGG
A
TAACGG
TTGCC
G
The cut produces overhanging ends, called sticky ends,
which will be used to “glue” the DNA.
Genetic Engineering- Molecular Cloning
 Where do you “paste” the cut DNA?
 Vector- an agent used to carry the desired gene into
another cell.
 Plasmid- type of vector; circular DNA molecule found in
bacteria that can replicate independently of the bacterial
chromosome
 The vector DNA is cut with the SAME restriction
enzyme.
 The cut produces the SAME overhanging ends, called sticky
ends, that match the organism’s DNA to the vector DNA.
Genetic Engineering- Molecular Cloning
 Step 1- Cutting DNA
Genetic Engineering- Molecular Cloning
 Step 2- Making recombinant DNA
 The DNA fragments from the organism are combined
with the vector DNA.
 The fragments match up using base pairing rules.
 DNA ligase bonds the ends of the DNA fragments.
Genetic Engineering- Molecular Cloning
 Step 3- Introduction into
a bacterial cell
 The recombinant DNA is
introduced into a bacteria, such
as E. coli
 Because bacteria reproduce by
binary fission, many copies of the
desired gene are made each time
the host cell reproduces.
Molecular Cloning
Video (click here)
Genetic Engineering
Do they always use bacteria?
 No! Eukaryotic cells can be transformed as well,
but not as simply as bacteria.
 Also, viruses can be modified to carry desired DNA
into a eukaryotic or prokaryotic cell.
Which is better:
receiving insulin extracted from
pig and cow pancreases or
receiving insulin produced by
molecular cloning?
Discuss.