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.