CHEMISTRY IN ANIMAL KINGDOM:
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By SINCHITA GHOSH HAZRA
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Batch 2k19 , Deptt. Of Chemical Engg.
- BIT Sindri , Dhanbad
Chemistry is not limited to beakers and
Laboratories. It's all-round us. Everything we hear, see, smell, taste,
and touch somehow or the other involves chemistry. If we observe the animal
kingdom, we find remarkable and astonishing use of chemistry. The bird and
animal kingdom is flushed with skills and caliber one can only term as
extraordinary. We have taken a lot of inspiration from them. Japan's high-speed
bullet trains have long, beak-like noses nearly identical to Kingfisher's bill
which makes the trains 10% faster and 15% more fuel-efficient and also achieve
quiet exit from tunnels which earlier created a loud boom. Also, the first
highway reflectors were made to mimic cat eyes.
Fluorescence and Bioluminescence in animals:
Fireflies, frogs, worms,
jellyfish, lanternfish, and sometimes even parrots can glow. There are mainly
two principles: Fluorescence and Bioluminescence. Talking of fluorescence- It's
a physicochemical energy exchange where shorter wavelength photons are absorbed
by a molecule and re-emitted as longer wavelength photons. Taking the example
of an American polka dot tree frog, in full sunlight the frog appears yellow
but in twilight the amphibian's fluorescence makes the creature appear in lime
green colour. For any creature to display fluorescence, it needs two things; a
molecule with excitable electrons and the right wavelength of light. In the
case of the frog, the molecules present in its skin and glands is Hyloin.
The molecules absorb a particular wavelength of light and emit a different one
causing the frog to glow.
You may
have seen the sparkle of fireflies in summer nights. The fireflies produce
light through a chemical reaction in their glowing abdomen, a process known as
bioluminescence. To emit light due to bioluminescence, we need a molecule
called luciferin, an enzyme luciferase, and some amount of oxygen.
Luciferase helps luciferin to take in oxygen and convert into
a substance called oxyluciferin whose electrons are in an excited state.
When the electrons in oxyluciferin come to the ground state, they emit
light causing the organism to glow. Luminous species are widely scattered, with
no discernible pattern. Luminous shrimps are known but no luminous crabs.
Luminous centipedes and millipedes are common but scorpions and spiders are
apparently non-existent.
Almost
half the animal phyla contain luminous forms but the number of representatives
is insignificant compared to total number of known animal species.
Bombardier Beetles and their "Chemical Weapon"
This insect has a built-in chemical weapon
in its abdomen which they can spray on the predators. The bug stores
chemicals such as hydrogen peroxide and hydroquinone in one
chamber and another chamber consist of enzymes and peroxidases that can
react with hydrogen peroxide to form oxygen gas and water. The
constituents of both the chamber are released into another chamber known as the
reaction chamber and benzoquinone is formed. The reaction is highly
exothermic and the mixture could reach up to 100-degree Celsius
temperature. The pressure due to the buildup of oxygen causes the hot mixture
to spray out. Once the spraying stops, they can reload the chamber and fire
again. Some beetles can spray the jet about 20 times before reloading it again.
Evolutionists remark that the beetle is actually an excellent example of
survival of the fittest. So, if you happen to encounter one such bombardier beetle,
just leave it alone.
Electric
eel looks like an eel but is actually a knife fish and is more closely related
to catfish than to an eel. Electric eels are in a class amongst the only
species in their genus. Under the water where light is scarce, these types of
fish use electricity to navigate, communicate, and sometimes even prey. There
are more than 350 species of fish which can produce its own electricity,
electric eels being one of them.
The fish's brain sends the signal
through its nervous system to the electric organ (found in a different place in
different species of fish). The organ consists of a special type of cell called
electrolytes. Normally electrolytes pump out Sodium and Potassium
to maintain a positive charge outside and negative charge inside the cells.
When the signal is received by the electrolytes, the ion gate opens causing the
positive ion to flow back in. In this case, one face is positively charged
inside and negatively charged outside but the far side has an opposite charge
pattern. These alternating charges drive a current. The signal from the fish's
brain reaches all the cells at the same time making the stack of cells act as
batteries connected in series. The current produced by electric eels is about
600 volts quite enough to immobilize their prey. Once the prey or predator is
immobilized, the eel can quickly swallow the prey or swim away from the
predator.
Rivalry among Ants:
Fire Ants are an aggressive species of ants mostly
found in America. The fire ant has a very painful sting which causes redness
and swelling. In some cases, people develop allergic reactions from the fire
ant bite, therefore, causing anaphylactic shock. Fire ant venom is mainly
composed of a mixture of >95 % bioactive piperidine alkaloids and
0.01 % of proteins, which comprise mainly allergens, phospholipases,
and neurotoxins. Fire ants and tawny crazy ants fight over food. Despite
being smaller, tawny crazy ants have an advantage because they produce an
antidote to the poisonous drop of venom. Tawny Crazy ants produce formic
acid which they then rub on themselves as an antidote to fire ant venom.
Without this antidote, only half of the poisoned tawny crazy ants could have
survived. More in the ant kingdom, we have bullet ants, bulldog ants, jack
jumper ants, etc. which can give you a hard time if you disturb them. The
bullet ant’s poneratoxin is a small peptide (25 amino acid residues long)
neurotoxin that can cause extreme pain, cold sweats, nausea, vomiting, and
even abnormal heart rhythms.
Underwater adhesion by mussels:
When it comes to underwater adhesion,
mussels are the pro players in this field. Human beings have been trying to
make glues that can sustain a wet environment but we are not up to par. These
tiny marine organisms have the ability to firmly attach in any surface be
glass, rock, plastic, etc. Furthermore, these mussels are capable of achieving
adhesion in a variety of conditions such as wet, dry, and salty environments.
The adhesive power of these mussels is basically due to two functional groups.
The first is 3, 4-dihydroxyphenylalanine (Dopa), which sports a catechol
side chain that can cross-link with rock surfaces or other adhesive proteins
through redox chemistry. The second is a cationic amino acid such as lysine.
Poly (catechol-styrene) may be the strongest underwater adhesive found to date.
Defensive strategy of Fall armyworm:
Fall armyworm is popular in destroying crops such
as wheat, maize, and rye. Plants like these have built defense compounds called
benzoxazinoids. This plant stores this so-called insecticide in a simpler form
i.e. beta-D-glucose. These plants have a special enzyme designed to release
the benzoxazinoids group when these plants are eaten by insects. This group is
toxic for all other kinds of multi-legged freeloaders but not for fall
armyworm. With methods such as chromatography, spectrometry, and nuclear
magnetic resonance it's found that the armyworm contains an enzyme which helps
to reattach the benzoxazinoid group to the sugar molecule but with
opposite stereochemical configuration compared to the original plant molecule.
The plant can no longer unmask the modified toxin. These armyworms are
naturally created chemists, aren't they?
Some
more facts:
1. Bees inject an acidic
compound called melittin which causes pain when they sting.
2. Wasp venom contains
traces of acetylcholine, another chemical that stimulates pain receptors.
3. Pheromones are
chemical signals that have evolved for communication between members of the
same species.
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