The Hammerling Experiment By Danny Nemeth Michael Leonard

The Hammerling Experiment By: Danny Nemeth Michael Leonard Allie Wrabel

Acetabularia 1. Danish biologist Joachim Hammerling needed cells large enough to operate on conveniently and differentiated enough to distinguish the pieces. 2. He chose the unicellular green alga Acetabularia, which grows up to 5 centimeters, as a model organism for his investigations. 3. Just as Mendel used pea plants and Sturtevant used fruit flies, Hammerling picked a model organism that was suited to the specific environmental question he wanted to answer, assuming that what he learned could then be applied to other organisms.

Acetabularia 1. Individuals of the genus Acetabularia have distinct foot, stalk, and cap regions; all are differential parts of a single cell. The nucleus is located in the foot. 2. As a preliminary experiment, Hammerling amputated the caps of some cells and the feet of others. 3. He found that when he amputated the cap, a new cap regenerated from the remaining portions of the cell (foot and stalk). 4. However, when he amputated the foot, no new foot regenerated from the cap and stalk. 5. Therefore, Hammerling hypothesized that the hereditary information resided within the foot of Acetabularia.

Surgery on Single Cells 1. Testing the Hypothesis: 1. select individuals from two species of the genus Acetabularia 1. Caps of cells look different 2. A. mediterranea 1. Disk shaped cap 3. A. crenulata 1. branched, flowerlike cap 2. 1. Cut the cell into 3 parts (Cap, Stalk, Foot) 3. 2. Combine the foot and cap of the cell with the stalk of the different cell 4. 3. Watch how the cap grows on both cells.

Conclusion The Experiment determined that: 1. If the caps would grow the same as before, the heredity information would have to be stored in the foot of the cell. 2. If the cell would have regrown different caps, the nucleus would not be found in the foot. 3. Now we understand that genetic instructions pass from the nucleus in the foot upward through the stalk to the developing cap.

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