2011 National DNA Day Online Chatroom Transcript

This is just one question from an archive of the National DNA Day Moderated Chat held in April 2011. The NHGRI Director and many genomics experts from across NHGRI took questions from students, teachers and the general public on topics ranging from basic genomic research, to the genetic basis of disease, to ethical questions about genetic privacy.

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Can some restriction enzymes not cut the right nucleotide sequence?      David Bodine, M.D., Ph.D.: I currently investigate the genetics of pluripotent hematopoietic stem cells (PHSCs) to improve the effectiveness of bone marrow transplantation and to find better ways to use these unique cells for gene replacement therapy. I'm also studying diseases that interfere with the ability of the stem cells to differentiate into red blood cells. Yes indeed. Restriction enzymes recognize a specific nucleotide sequence, but if one of the bases is modified, it can cause the enzyme not to recognize the site. For example in mammals, some C residues get modified with a CH3 (methyl) group. This can inhibit the activity os some enzymes, but not all. In bacteria, putting a methyl group on As inhibits restriction enzymes. Westview High School in CA (9th grade student)

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