|MadSci Network: Biochemistry|
Hello Marissa, Heat kills living organisms primarily by denaturing proteins. Proteins typically function in a very narrow range of temperatures; for humans, this temperature is 37 degrees C. Once the temperature rises more than a few degrees above 37, proteins start to denature (literally, fall apart). And since so many of your body's structures and functions are protein-based, once denaturation starts, all heck breaks loose. As an example, consider the structure of cell membranes. You probably know that a cell membrane consists of a phospholipid bilayer. Well, there are also many kinds of proteins embedded in the phospholipid bilayer, doing a variety of jobs - regulating what enters and leaves the cell, maintaining the chemical composition of the cell, identifying the type of cell to other cells, maintaining the integrity of the cell membrane itself, and providing sites for many biochemical processes. You can imagine that if all these proteins were to crumble and fall to pieces, due to heat or some other mechanism of denaturation, the cell wouldn't function very long. Nucleic acids (DNA and RNA) are also susceptible to denaturation by heat. When DNA is denatured, the strands of the double helix unzip and fall apart. As you can imagine, once the nucleic acids are denatured, the organism is toast, so to speak. I hope this helps! Allison J. Gong Mad Scientist
Try the links in the MadSci Library for more information on Biochemistry.