July 16, 2019 Tuesday
Bedtime Story
Thermodynamics of Life-Supporting Molecules
The technical name for these highly
specialized proteins located on the cellular membrane of the vascular smooth
muscle cells is adrenergic receptors which are a class of G protein-coupled
receptors.
The name G comes from the word “guanine”
(they are also known as guanine nucleotide-binding protein) as they have the
ability to bind to guanine and hydrolyze guanosine triphosphate (GTP) to
guanosine diphosphate (GDP) on the lines of the most famous biological reaction
of ATP hydrolysis.
The release of energy stored in the
phosphoannhydride bonds or pyrophosphate bonds having P-O-P linkage transformers
chemistry into biochemistry giving that whiff of life to chemistry.
That certain types of chemical bonds
requiring relatively low chemical energy to break them but which release a
large amount of energy (simply because the total energy of the system is
lowered dramatically as the resulting compound has far greater stability) can
give life to pure chemistry is one of the most counter-intuitive (and rarely
appreciated) facts of life.
The water falling from a massive cascading waterfall
capable of running turbines and thereby generating power that sustains an
entire organized town or a city is perhaps the best analogy that I can give
you.
The water at the top of waterfall has
trapped potential energy in the same manner as the bonds have that it acquired
from solar energy through photons during evaporation.
Evaporation as you would know is an
endothermic process (just like some specific bond formations are) in that it
requires energy in the form of heat for it to occur.
If ATP and its phosphoannhydride bonds or
pyrophosphate bonds is one “miraculous” molecule in biochemistry then so is the
G protein.
If the bonds in the ATP molecules are
analogous to the stored energy in the water at the height of waterfalls then
the G proteins as a class can be compared to diode valves or maybe even
transistors of the computing industry.
If you think this analogy is bit too
farfetched let me surprise you with a 2012 paper published in Nature
Nanotechnology titled “A protein transistor made of an antibody molecule and
two gold nanoparticles.”
The aim of this paper is to give a
demonstration with a single cell that investigations of such single-molecule
based biological functions might lead to large scale manufacture of integrated
bioelectronic circuits.
The only problem that I foresee in such
attempts being made to replicate life is that we apes are most certainly not
likely to get that much luxury of time that the nature got – we should in all
probability annihilate ourselves as species much before 4.3 billion years.
G proteins – much like the historical
thermionic vacuum-tube diodes or triodes and modern day transistors - are the
molecular switches of cells whose primary function to transmit a signal from
outside of cell to its interior.
The state of their binding to GTP or GDP
determines their status of “on” and “off”.
Stay tuned to the voice of an
average story storytelling chimpanzee or login at http://panarrans.blogspot.com
Good night Mon Ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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