This “desaturase” enzyme makes the altered fatty acids more crooked and thus less able to stick together. An enzyme is stimulated that begins to add double bonds to the fatty acids of the cell membrane phospholipids. In my Cell Biology class I talk about changes that can be seen in cell membranes in both amphibians (like the green frog) and reptiles (like turtles and snakes) as seasonal temperatures begin to fall. How could they survive this extreme thermal trauma? Frogs are ectothermic (they rely on the heat of their environment for their body heat) and would seem quite vulnerable to freezing solid in the very cold winters of Western Pennsylvania even if they were underground or underwater. But where these frogs sit out the winter was just the beginning of this story. As we talked about her frogs’ appearance, behavior, and songs I decided that they must be Northern green frogs ( Lithobates clamitans melanota), and since her pond is quite shallow and expected to freeze solid over the winter, and also because it is surrounded by a very dense growth of myrtle, I speculated that the green frogs (which can either hibernate underwater or underground) would leave the soon-to-be-solid pond and dig a hibernaculum in the soil under the protective cover of the myrtle. Wikimedia Commons)Ī few weeks ago Jane Viti, one of my teaching colleagues, asked me what was going to happen to the two frogs that had been living in her small, backyard pond all summer. Northern green frog (photo by Contrbaroness.
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