Download
1 / 8
80 likes | 212 Vues
Recombinant DNA technology is at the forefront of biotechnology, enabling groundbreaking advances such as genome sequencing, genetic engineering, and cloning. This technology involves the use of restriction endonucleases, enzymes produced by bacteria that cut DNA at specific sequences, often palindromic in nature. With over 100 types of these enzymes identified, scientists can manipulate DNA fragments to create recombinant DNA by ligating pieces together using DNA ligase. This has widespread applications in research, medicine, and agriculture, allowing for the insertion of new genes into various organisms.
E N D
Introduction • If you pay any attention at all to the news, you cannot avoid stories about biotechnology: sequencing a genome, identifying a gene, analyzing ancient DNA, fingerprinting DNA, cloning something, genetic engineering, etc. Have you ever wondered, “How do they do that?”
Making Recombinant DNA (rDNA) • Enzymes called restriction endonucleasesrecognize specific DNA base sequences and cut the DNA at or near the recognition sequence. • Produced by bacteria. • When added to a t.t. containing DNA, they enzyme will cut the DNA molecules at every occurrence of its recognition sequence. • http://www.dnalc.org/resources/animations/restriction.html: Video of restriction enzymes in action!
Palindromes • Most commonly used restriction enzymes recognize palindromes. • Base sequences in which both strands read the same in the 5’ to 3’ direction. • Ex. 5’ GAATTC 3’ and the complimentary strand would read from 3’ to 5’ (left to right) as follows: 3’ CTTAAG 5’.
How many restriction endonucleases are there? • Little over 100. • Names indicate the organism from which they were purified. • EcoRI: Escherichia coli • HindIII: Hamemophilusinfluenzae • BamHI: Bacillus amyloliquefaciens • Each enzyme bind to & cut at specific DNA base sequences every time. • Cut pieces are called restriction fragments.
Now what? • Now we have small pieces of (restriction fragments) DNA in which we could: • Electrophorese the fragments. • Glue 2 or more fragments from different organisms back together. Glue = DNA ligase. Now the DNA is called recombinant DNA! • Ex. If your goal is to insert a new gene into a microorganism, plant, or animal to clone a gene.
