1. Ligase + Methylation Biotech Crash Course By: Alice, Mandy, and Sageban

2. What is Ligase?  The specific type of enzyme found in DNA  Repairs single strand discontinuities in double stranded DNA  The formation of ligase is two nucleotides joined together by a phosphodiester bond

3. How is Ligase Used?  The overhang that is left after DNA is cut, is repaired by ligase, it catalyzes the chemical reaction that rejoins the DNA sugar-phosphate bonds  Ligase is used in gene cloning to join DNA molecules

5. Video of Ligase  http://www.dnalc.org/view/15476- Genetic-engineering-inserting-new-DNA- into-a-plasmid-vector-3D-animation-with- with-basic-narration.html http://www.dnalc.org/view/15476- Genetic-engineering-inserting-new-DNA- into-a-plasmid-vector-3D-animation-with- with-basic-narration.html

6. What is Methylation?  DNA methylation is the modification of a strand of DNA after it has replicated  This is done by the addition of a methyl group to position 5 of the cytosine pyrimidine ringmethyl groupcytosine  Can be inherited through cell division

7. How Methylation is Used  Methylation is used to alter the gene expression pattern in cells so that they can “remember where they have been”  It also can be used to suppress the expression of viral genes that have been incorporated over time  When the methyl group is added it inhibits transcription initiation and it inhibits cell growth and differentiation

9. Video of Methylation http://www.youtube.com/watch?v=EBbQw m0HJK0 1:32