Biology Reference
In-Depth Information
FIGURE 6.2
AceDB vertical description of genome. The area shown represents about 700 base pairs
(roughly 283300-284000) on the X chromosome of the worm genome in the region of a gene called
F09B9. The various boxes in the middle of the image indicate the extent of various features such as
exons, SNPs, and coding start and stop sites. (http://www.acedb.org/Cornell/angis/genetic_maps.html.
Reproduced by permission of Jean Thierry-Mieg.)
on. A simple text fi le format suffi ced to defi ne this structure. Each object
belonged to a particular “class” that defi ned the organization and types
of data permitted for the object.
This system of classes and objects is familiar to software engineers
as “object-oriented” programming. In an object-oriented programming
language, classes defi ne the abstract characteristics of objects (both
things that an object has and things that it can do), while the objects
themselves are particular instances of a class. The advantage of such a
scheme is that it is supposed to mirror how we think of objects in the
real world.
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For example, one could defi ne the class “vehicle” as includ-
ing any object with “wheels” and a “power source”; subclasses would
include “car,” which must have four “wheels” plus an “engine”; “truck,”
which must have six “wheels” or more plus an “engine”; and “bicycle,”
which must have two “wheels” plus two “pedals.” The particular car
that I own would be an object within the class “car.” The i rst object-
