Chemistry Reference
In-Depth Information
Figure 2.
Chromosomal DNA,
DNA double helix, genes. The
top part of this figure gives the
basic “building blocks” of
nucleic acids, i.e., the
nucleotides, and their
elementary components, the
ribose (or deoxyribose) sugar
units and purine/pyrimidine
bases. The carbon numbering
scheme for ribose and
deoxyribose sugars is given as
well. A simplified
representation of double-
stranded DNA(dsDNA) is
likewise presented. Although
not shown in this drawing,
A
T base pairs form 2
hydrogen bonds, G
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C base
pairs form 3 hydrogen bonds,
and the DNA helix itself
exhibits a twisted helical
structure. Lastly, chromo-
somes are DNA-protein
complexes that are extremely
condensed and supercoiled.
The chromosome contains
numerous genes, and if we
were to magnify or enlarge a
small region of the
chromosome, we would
observe that the chromosome
is organized into chromatin
and nucleosome DNA-protein
superstructures. Such compact
packing allows an incredible
amount of genetic information
to be stored in a very small
volume within the nucleus.
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