The study of genetics can be mind-numbing. But fifth graders participating in the Huntington School District’s SEARCH program embraced the subject matter during a recent 12 week unit that culminated in a fun lab.
Maryann Daly, the SEARCH program’s chairperson-teacher said she scheduled the lab the week before the winter recess on purpose. Having already extracted DNA from wheat germ at the DNA Learning Center in Cold Spring Harbor earlier in the month, the youngsters were looking forward to doing the same from strawberries during their weekly class.
“Not to disappoint, thawed strawberries were placed into poly bags that each team had in their possession,” Mrs. Daly explained. “In order to break through the tough cell wall, each student mashed the strawberries into a puree state, being careful not to open the bag and explode the contents. The next step was to break through the cell membrane, which they did by measuring 10 milliliters of cell lysis solution and then adding it to their poly bag; again carefully mixing both chemical and strawberry with their fingers.”
The messy of part of the lab followed. “While one student slowly poured a small amount of the strawberry mixture over a cheese cloth, the second student had to squeeze the juice out of the cloth in order to collect the lysate in a deep chemplate,” Mrs. Daly said. “This was done several times until at least three quarters of the liquid was collected and separated from the mushy part of the strawberry.”
Students then poured a DNA precipitate solution into a test tube. “This was the final step to the lab; getting through the nuclear membrane of the strawberry,” Mrs. Daly said. “An eyedropper was used to extract the strawberry lysate from the chemplate holding the pink liquid. Slowly, 15 drops of the lysate was squeezed into the tube which held the precipitate. Even though the directions stated to wait several minutes in order for the strawberry DNA to become visible, it was very soon afterwards that the students were able to see the DNA swirl and bubble to the top of their test tube.”
The fifth graders were clearly pleased with the successful outcome of their experiment. “You can see the delight on the faces of everyone, all in awe of the DNA,” Mrs. Daly said. “They wanted to touch the DNA as soon as they collected it from their test tubes using a wooden spindle. Everyone wanted to take the samples home.
The lab made extracting DNA from real strawberries fun. “It also made the SEARCH room smell like strawberries for the rest of the day,” Mrs. Daly said. “When the sixth grade SEARCH students came into the room they remembered how much they had enjoyed their DNA extraction lab the previous year. It always makes me smile to see how fascinated the children are when they see real DNA in front of them. Future scientists; a win-win for all of us.”
The weekly SEARCH (Scholastic Enrichment and Resource for the Children in Huntington) pull-out program involves the top ten percent of students in both the fifth and sixth grades in the district. Students qualify for participation as a result of their respective percentile rank on state assessments and the OLSAT.