Animal anti-freeze - The chemistry of almost everything (3/31)

Uploaded by OUlearn on 03.09.2009

It's not just astronauts that have to survive in hostile environments.
Some creatures have to cope with freezing conditions on Earth.
Deep below the ice and snow of the Canadian tundra
is a hibernating frog.
But unlike most hibernating creatures,
it survives not by avoiding the extreme low temperature,
it succumbs to it.
Most of its blood, even its eyes, have frozen solid.
But what about the thaw?
Most living creatures can't survive freezing
because as the water in their cells turns into ice, it expands.
The cells would burst, destroying their structure.
But he survives because his cells have specially elastic walls
and some of them are filled with high levels of a key chemical -
Glucose stops the water in these delicate cells from freezing
and so prevents destruction.
No human could tolerate concentrations of sugar
at this level.
And the frog has a mechanism to reabsorb the sugar
as it thaws out.