BiotechnologyThe use of biological processes,

organisms, or systems to manufacture products intended to improve the quality of human life.

Transgenics• Genetic engineering

makes it possible to transfer DNA sequences from one organism to another

• REMEMBER- DNA is universal

• A gene taken from one species can be replicated in another species.

Recombinant DNA• Recombinant DNA contains DNA from

2 or more different sources.• So how does DNA get from one species

to another?• Vector: a mechanism needed to transfer

DNA from one organism to another– Microinjection– Gene Gun– Bacteria Plasmid– Virus

Recombinant DNA• The host cell is often a bacteria cell• Bacteria are used because they have

plasmids• A plasmid is a circular

piece of DNA that exists

apart from the

chromosome and

replicates independently of it.

• So how do I take a gene from one organism and put it into another?

• We need to use Restriction Enzymes

What are Restriction Enzymes?

• Proteins• Used by bacteria to cut viral DNA• They “restrict” the growth of viruses

• What does this have to do with transgenics?!

Restriction Enzymes• Cut strands of DNA at specific nucleotide

sequences• There are many different restriction

enzymes that each cut DNA at different nucleotide sequences

• Usually occurs at a palindrome

5’ GAATTC3’ CTTAAG

Sticky Ends• Most restriction enzymes cut

DNA with a staggered cut• The staggered cuts leave

the DNA with end pieces “sticking off” – We call these “sticky ends”– These exposed N-bases will

want to join with other complimentary exposed bases

So what ?• What do you predict could happen if two

pieces of DNA are cut with the same restriction enzyme???– YES! They will have the same “sticky ends”

– How could we use this???

• Restriction Enzymes can be used to make Recombinant DNA.

• The gene of interest can be isolated using Restriction Enzymes

Making Recombinant DNA…

• Once the gene is isolated, how do we join it with the organism’s DNA?

• Cut the organism’s DNA with the same restriction enzyme…why– The sticky ends will naturally be attracted to

each other• Add DNA LIGASE: an enzyme that seals

the fragments together

• Now whenever the bacteria plasmid replicates, the gene will be cloned.

• Gene Cloning: the production of many identical copies of the same gene.

• You have created a Transgenic Organism!

–organisms that contain functional recombinant DNA (rDNA) from a

different organism

• http://www.sumanasinc.com/webcontent/animations/content/plasmidcloning.html