Biomedical Engineering Reference
In-Depth Information
Table 3.1
Comparison between DNA and RNA
DNA
RNA
Stands for
Deoxyribonucleic acid
Ribonucleic acid
Definition
A nucleic acid that contains the
genetic instructions used in the
development and functioning
of all modern living organ-
isms (scientists believe that
RNA may have been the main
genetic material in primitive
life forms)
A single-stranded chain of alternat-
ing phosphate and ribose units
with the bases adenine, guanine,
cytosine, and uracil bonded to
the ribose. RNA molecules are
involved in protein synthesis
and sometimes in the transmis-
sion of genetic information
Job/role
Medium of long-term storage
and transmission of genetic
information
Transfer the genetic code needed
for the creation of proteins from
the nucleus to the ribosome
Unique features
The helix geometry of DNA is of
B-form. DNA is completely
protected by the body, i.e., the
body destroys enzymes that
cleave DNA. DNA can be dam-
aged by exposure to ultraviolet
rays
The helix geometry of RNA is
of A-form. RNA strands are
continually made, broken down,
and reused. RNA is more resist-
ant to damage by ultraviolet
rays
Predominant structure
Double-stranded molecule with a
long chain of nucleotides
A single-stranded molecule in most
of its biological roles and has a
shorter chain of nucleotides
Bases and sugars
Deoxyribose sugar; phosphate
backbone; four bases: adenine,
guanine, cytosine, and thymine
Ribose sugar; phosphate backbone.
Four bases: adenine, guanine,
cytosine, and uracil
Pairing of bases
A-T (adenine-thymine), G-C
(guanine-cytosine)
A-U (adenine-uracil), G-C
(guanine-cytosine)
Stability
Deoxyribose sugar in DNA is less
reactive because of C-H bonds.
Stable in alkaline conditions.
DNA has smaller grooves,
which makes it harder for
enzymes to “attack” DNA
Ribose sugar is more reactive
because of C-OH (hydroxyl)
bonds. Not stable in alkaline
conditions. RNA has larger
grooves, which makes it easier
to be attacked by enzymes
Propagation
DNA is self-replicating
RNA is synthesized from DNA
when needed
unique luminescence properties of semiconductor QDs also show a great potential to
develop RNA sensors by implementing the QDs as luminescent labels.
3.2.1 Direct Fluorescence Labeling
QDs have high extinction coefficient and high quantum yield, which should dramati-
cally increase the sensitivity in theory. Therefore, it was thought that the direct labe-
ling of miRNA with QDs could be well used in miRNA detection and applied in
microarray. Liang et al. realized microRNA detection in a microarray configuration
