Biomedical Engineering Reference
In-Depth Information
Hydrogen bond
5end
3end
OH
O
OH
T
P
-O
O
A
O
CH
2
H
2
C
O
2 bonds
O
-
O
P
O
O
O
O
C
P
O
-O
G
CH
2
O
H
2
C
O
O
-
3 bonds
O
P
O
O
O
O
P
T
O
A
-O
O
CH
2
H
2
C
O
O
-
2 bonds
O
P
O
O
O
O
P
C
O
H
2
C
G
-O
CH
2
O
O
O
-
3 bonds
O
P
O
OH
OH
3end
5end
7. 1
Structure of nitrogenous bases that make up the framework of
DNA. Note the hydrogen bonding between the base pairs, and the
anti-parallel nature to the two strands of the double helix. (Image
created by Kamila Dabrowski, St Peter's University, Art Department,
Graphic Arts, Jersey City, NJ.)
nucleic acids into manageable pieces that could accurately be sequenced.
This led to the announcement in 2000 by President Bill Clinton that the fi rst
draft of the entire sequence of base pairs in the human genome had been
established. This undoubtedly is one of the greatest human scientifi c accom-
plishments, and with it came the knowledge that at the nucleotide level all
humans were 99.9% identical. However, it is this 0.1% difference that is at
the heart of the genetic diversity seen in humans. The vast majority of these
differences, many being just a single base difference, are found in the non-
coding areas of the genome. It is those relatively rare changes that occur
