Allows us to combine genetic material from different sources. The first step in recombinant DNA technology is often making a DNA fragment
What is DNA fragment?
A bit of DNA containing a gene
What does Recombinant DNA technology involve?
Transferring a fragment of DNA from one organism to another.
Why can transferred DNA be used to produce of protein in the cells of the recipient organism?
Because the genetic code is universal (the same DNA base triplets code for the same amino acids in all living things), and because transcription and translation mechanisms are pretty similar too
What are organisms that contain transferred DNA known as?
transgenic organisms
In order to transfer a gene from one organism to another, first need to get a DNA fragment containing the gene you're interested in (target gene)
Method using reverse transcriptase
1. Isolate mRNA from cells
2. Mix mRNA with free DNA nucleotides and reverse transcriptase
3. Reverse transcriptase uses mRNA as template to synthesise new strands of cDNA
More recently, technology has been developed so that fragments of DNA can be synthesised from scratch, without the need for pre-existing DNA templates. Instead, a database contains the necessary information to produce the DNA fragment. This means that the DNA sequence does not have to exist naturally - any sequence can be made
How a gene machine works
1. Sequence required is designed (if one doesn't already exist)
2. First nucleotide in the sequence is fixed to some sort of support e.g. a bead
3. Nucleotides are added step by step in the correct order, in a cycle of processes that includes protecting groups
4. Protecting groups make sure that the nucleotides are joined in the right points, to prevent unwanted branching
5. Short sections of DNA called oligonucleotides, roughly 20 nucleotides long are produced
6. Oligonucleotides are broken off from the support and all the protecting groups are removed
7. Oligonucleotides can then be joined together to make longer DNA fragments