What Is Biotechnology? - Biotechnology and Your Health: Pharmaceutical Applications - page 3

Gregor Mendel figured this out in the late 19 th century by carefully
conducting breeding experiments with peas. However, his work
was not noticed until 34 years later, when several scientists came
upon his papers and realized the importance of his discoveries.
Building on Mendel's findings, scientists studied plants, animals,
and humans, and determined several things: 1) genes are carried
on chromosomes , structures in the cell's nucleus ; 2) genetic informa-
tion resides in the chemicals that make up the chromosomes; and
3) traits are generally based directly or indirectly on the proteins
produced in cells.
Stop and Consider
It took 34 years for biologists to appreciate Gregor Mendel's work on
the genetics of peas. Does it surprise you that something that now
seems like a profound discovery was not immediately recognized?
What do you think keeps people, even scientists, from understanding
the importance of a discovery when it is first made?
Proteins (also called polypeptides ) are composed of one or more
linear chains of amino acids . There are 20 different amino acids that
share a common structure, with side chain groups that vary in size,
shape, charge, chemical reactivity, and solubility in water. Proteins
can be small (made up of just a few amino acids) or very large
(composed of thousands of amino acids). The biochemical prop-
erties, three-dimensional shape, and function of each protein
primarily result from the sequence of the amino acids that make
up the particular protein. Proteins do many things: they provide
structure, allow cells and whole organisms to move, and permit cells
to produce and break down all kinds of chemicals to gain nutrition
and energy. In complex organisms such as animals, plants, and
insects, many proteins travel around the body to carry gases for
respiration (breathing) and to carry signals between and among cells