Imagine that an extraterrestrial life-form has been recovered from a meteorite by a deep space probe that
has a ravenous appetite for sand. Your job is to come up with a preliminary analysis of its bioenergetic
pathway. On close examination you note that the biochemical pathway employed by this creature has
some features in common with your own. You note that the alien has a basic cellular structure similar to
that of Earth-based creatures. It has what you would consider to be a cytoplasm, nucleus, and other basic
organelles. In addition, the creature appears to be capable of using oxygen in the course of its metabolism.
Following a rigorous biochemical analysis, you note the following points:
A glycolysis like process begins with the alien's basic food stuff of sand particles. Specifically, the first
molecule in the pathway contains 126 silicon atoms (Si
b.In the process of metabolizing the Si126, you note that the creature uses up 55 energy- carrying molecules that you have named ZTP (since it is an unknown triphosphate-bearing molecule that gives
the creature 'zip') in converting the Si126to 7 molecules of Si
18. Also, in the process of breaking down one molecule of Si126, 10 molecules of an electron-carrying substance you have called EADH are formed.
c.Each Si18 molecule is broken into two molecule with the creation of 9 ZTP molecules and 10 EADH
molecules. Each molecule of Si18 gives off 4 SiO2 molecules in this step (Si 7 left).
d.Each Si7 goes through a cyclic process in an organelle similar in structure to our own mitochondrion in
which the Si7 is completely oxidized to SiO2. In the process, 5 ZTP, 5 EADH, and 10 EADH2 are released.
e.Each molecule of EADH is converted to 10 ZTP, and each molecule of EADH2 is converted to 5 ZTP.
(NOTE: Each EADH formed in step (b) is converted to two molecules of EADH2 when it passes into
the mitochondrion-like structure.)
How many ZTP and SiO2 molecules will be formed in the complete metabolism of 1 molecule of Si
126? Show all your work in the space below. Include in your calculations appropriate silicon related
names for each of the key steps. [20 Application Marks]