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Studying the genomes of organisms
GENE TECHNOLOGY
Genetic Engineering- From The BeginningCohen 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?
DrugsVaccinesImproving cropsAnimal FarmingCloning
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.
CTGAATTCCG
GACTTAAGGC
CTG|AATTCCG
GACTTAA|GGC
EcoR1 recognition site
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?
Step 1- Cutting DNAThe DNA from the organism containing the
desired gene is cut using a restriction enzyme.
EX: ATTGCCTAACGG
The cut produces overhanging ends, called sticky ends, which will be used to “glue” the DNA.
Genetic Engineering- Molecular Cloning
A TTGCCTAACGG G
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
Genetic Engineering- Molecular Cloning
Step 2- Making recombinant DNAThe 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 cellThe 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 EngineeringDo 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.
DNA
Which is better: receiving insulin extracted
from pig and cow pancreases or receiving
insulin produced by molecular cloning?
Discuss.