Question 3

[eo5]

I understand the answer explanation but I thought at 45C the protein might denature because our optimal body is about 37C.
Is it possible for one body part to have such significant temperature increase compared to other body parts?

[admin]

There is great variation of temperatures at which proteins denature.

Consider the proteins in your skin: keratin, collagen, elastin. Humans with sufficient hydration, no direct sunlight which could increase the skin temperature further, can survive exposure to temperatures above 45C, even between 50-60C without any concern over denatured skin proteins nor denatured proteins in the airways.

Different forms of hemoglobin have been found in other types of organisms besides humans. Some thermophilic (thrives at high temperatures) bacteria use hemoglobins that function normally between 50C and 60C: http://content.febsjournal.org/cgi/content/full/272/16/4189.

From the MCAT point of view, it's true that the questions can be a bit tricky at times. However, the fact that denatured proteins are never mentioned and then suddenly while comparing temperatures which, on an experimental scale, are only mildly different from each other, it would not seem fair that you would have had to make a call as to whether or not an 8-10C increase in body temperature is enough to denature hemoglobin. Had the temperature been 100C (which everyone knows denatures proteins in an egg thus changing its form to a "hard boiled" egg) then you would be expected to assume that the temperature was so extreme that hemoglobin would denature.

[admin]

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