This document summarizes several theories on the origin of biomolecules:
The Oparin-Haldane theory and Miller-Urey experiment suggested that simpler organic molecules could form from carbon dioxide and a reducing agent like hydrogen in the conditions of early Earth. These molecules could then combine to form more complex biomolecules through chemical evolution.
The theory of mica sheets proposed that the spaces between thin mica layers provided conditions for the first biomolecules to arise and evolve, similar to primitive cells. Heating and cooling could drive chemical reactions.
A Japanese study found that ocean impacts from meteorites containing carbon, iron, and nickel produced amino acids and other organic molecules, suggesting impacts could have contributed
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Origin of biomolecules.. sairam
1. Name of the Student: D.Sairam ( Ist
Semester IBT)
Name of Teacher: Vineet Sharma
Course Code: BSBT ā 102
Assignment Code: U1A1
Presentation Title: Origin of
Biomolecules and the Cause of their
Formation
3. What are Biomolecules?
ā¢ Biomolecules can be defined as molecules that are produced by
living organisms and form the structural basis of all living
organisms
ā¢ Hence, one may also call them as āBiogenicā molecules too. The
most common Biomolecules are proteins, lipids, nucleic acids,
carbohydrates and vitamins.
ā¢ They have existed since time immemorial and there are numerous
theories propounded describing their origin.
ā¢ Most notably people believe that the conducive environment in the
past resulted in the binding of simpler molecules such as amino
acids and others together, thus forming Biomolecules.
4. Foreword to Theory
ļThe Oparin-Haldane Theory first brought about a concrete
analysis of the origin of Biomolecules.
ļThe Miller Urey Experiment determined that molecules
can spontaneously combine and form organic molecules in
primordial Earth conditions
ļIt was thought that evolution, from a chemical standpoint,
was simply one archaic autocatalytic reaction branching out
to numerous different reactions, using different substrates
and generating different products over the course of billions
of years.
ļThe primordial Earth did not have Biomolecules; thus,
reactions were not catalyzed by enzymes. Inorganic catalysts
must have been used for reactions to take place.
5. Theory of
Chemical
Evolution
ā¢ This theory was proposed by
Oparin and Haldane based on the
Urey- Miller Experiment. The
chemoautotrophic origin of life
model, the starting material for all
Biomolecules and organic
molecules was carbon
dioxide.[1] Because carbon dioxide
is in a fully oxidized state, all
reactions involving carbon
dioxide must have been reductive,
and a reducing agent must have
been necessary. The reducing
agent must have fit the following
criteria:
Urey- Miller
6. ļ¶It had to be strong enough to reduce carbon dioxide
in order for a reaction to occur.
ļ¶I t must have been readily available in the
environment of primordial Earth.
ļ¶It must be somehow connected to today's known
biochemistry.
ļ¶It must remain stable even after going through many
reactions.
ļ¶This is the most wide spread and accepted theory
however there are several other thesis that state that
Biomolecules were created from external sources.
7.
8.
9. Theory of Mica Sheets
ā¢ In 2007, Professors from University of California (including Helen Hansma)
claimed that life and Biomolecules on earth may have originated as an organic
filing between layers of Mica Sheets.
ā¢ It proposes that proposes that the narrow confined spaces between the thin layers of
mica could have provided exactly the right conditions for the rise of the first
Biomolecules ---- effectively creating cells without membranes.
ā¢ . The separation of the layers would have also provided the isolation needed for
Darwinian evolution RNA plays an important part in translating the genetic code,
and is composed of nitrogenous bases, sugar, and phosphates
ā¢ The theory adds on by saying that Mica layers are held together by potassium. The
concentration of potassium inside the mica is very similar to the concentration of
potassium in our cells. And the seawater that bathed the mica is rich in sodium, just
like our blood.
ā¢ The heating and cooling of the day to night cycle would have caused the mica
sheets to move up and down, and waves would have provided a mechanical energy
source as well, according to the new model.
10.
11. Theory of Ocean Impacts
ā¢ Another theory published in 2009 by a group of Japanese scientistsā claims that
Biomolecules have originated owing to oceanic impacts
ā¢ In a Letter written to Nature Geo science they assert āIntense impacts of
extraterrestrial objects melted the embryonic Earth, forming an inorganic body with
a carbon-dioxide- and nitrogen-rich atmosphere1,
ā¢ Certain simple organic molecules have been shown to form under conditions
resembling meteorite impacts, although the link between these events and the
development of more complex molecules remains unclear3.
ā¢ Ordinary chondrites, the most common type of meteorite, contain solid carbon, iron
and nickelāelements essential to the formation of organic chemicals4, 5. Here we
use shock experiments to recreate the conditions surrounding the impact of
chondritic meteorites into an early ocean. We used a propellant gun to create a high-velocity
impact into a mixture of solid carbon, iron, nickel, water and nitrogen.
12. After the impact, we recovered numerous organic molecules,
including fatty acids, amines and an amino acid. We suggest
that organic molecules on the early Earth may have arisen from
such impact syntheses. As the natural impacts that were
frequent on the early Earth are more sustained and reach higher
pressures than our experiments6, 7, they may have resulted in the
synthesis of a greater abundance, variety and complexity of
organic compounds.ā
This theory also does not have any concrete backing yet.