Jaekwan Kim
Professor Marianne Gerard
BIO 104
October 23, 2014
Entropy
Entropy is defined as a thermodynamic quantity representing the unavailability of a
system’s thermal energy for conversion into mechanical work, often interpreted as the
degree of disorder or randomness in the system. For example, one might call a bedroom
with clothes and books scattered all round the floor a high entropy system. If books and
clothes were instead neatly stacked into piles, this will become a low entropy system. If
there were a large number of books and pieces of clothing in the room and we divided the
room into some number of squares, there would be a large number of possible
configurations in terms of which clothes and books were in which squares. If on the other
hand we neatly stacked all the clothes into a pile that occupied only one square and did the
same with the books, then we would see that this is essentially the only configuration. This
same logic also is applied to DNA. Shannon entropy is a simple quantitative measure of
uncertainty in a data set. One qualitative way to think about it in terms of sequences is that
if a sample set is drawn from a large population, the Shannon entropy could be considered
as a measure indicative of your ability to guess what amino acids would be in the next