DNA as molecular LEGO brick (part 2)
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Transcript of DNA as molecular LEGO brick (part 2)
DNA as molecular lego brickpart 2: introduction to self-assembly
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for a long time, we have been mostly rely on
TOP-DOWN fabrication to build our daily objects
example 1: balinese wood carving
in TOP-DOWN assembly:
the final product is smaller than the starting material
and there must be a constructor, such as the balinese sculptor
in the example shown above
contrary to most NON-LIVING objects,
LIVING MATERIAL assembles by itself from
smaller components
example: cells -> human
this process is commonly called as
SELF-ASSEMBLY
or
BOTTOM-UP ASSEMBLY
the macro-scale analogy of molecular self-assembly
is LEGO bricks that bounce around and form
elaborate structures by itself !!!
“do it yourself” self-assembly
the movie (1.4 MB) can be freely downloaded at
http://www.pnas.org/content/suppl/2007/12/05/0709489104.DC1/09489Movie1.mov
shaking a bottle containing of
magnetized lego brick
(3)
(1) initial state:
unordered system(2)
(4) product:
ordered structure
the movie (1.4 MB) can be freely downloaded at
http://www.pnas.org/content/suppl/2007/12/05/0709489104.DC1/09489Movie1.mov
“do it yourself” self-assembly
yellow components represents smaller subunit
magnet represents physical interactions between subunits
shaking represents thermal vibrations
shaking a bottle containing of
magnetized components
thermal energy grows increasingly important as we look
at smaller scale
using equipartition theorem, at room temperature
we, human, shakes at the speed of ~0.00000000001 m/sec
hydrogen atom shakes at the speed of ~100 m/sec; so
thermal energy MATTERS at small scale
molecular self assembly uses thermal energy to shake
its components
v !!
kBT
mfrom the equipartition theorem
where KB is boltzmann’s constant, T is temperature in kelvin, and m is mass
PRINCIPLES of self-assembly
1. larger structure is built from smaller subunits
2. there are some physical interactions between
subunits- the shape and physical interactions determine the final
structure
3. energy source is required for shaking the subunits.
- life utilizes thermal energy for its self-assembly
4. the process is random (Stochastic). - Subunit can attach or detach to other subunit or a larger
structure.
- Larger structures form and disassemble by themselves all
the times
Achievements of DNA nanotechnology
CatalystALGORITHMIC
SELF ASSEMBLYMolecularmachinesCIRCUITDNA origami
Next: DNA ORIGAMI