this a group project

1. The Origin of Life
Group 16 Nat Sci project
Submitted to : Prof. Nerissa Torreta

2. Theories on the Origin of Life
I. Theory of • Emmaruth Fandialan
Spontaneous
Generation/Abiogen
esis Theory
II. Biogenesis Theory • Byron Cayabyab
III. Cosmozic • Paolo Amer
Theory/Panspermia
IV. Theory of Special • Patricia Lijauco
Creation
• Emmaruth Fandialan
V. RNA World Theory

3. Introduction
Biology is known to be the study of life and living organisms. While this
discipline, which seeks to answer the question, “What is Life?”, is already quite
a complicated subject to touch upon in scientific and philosophical terms, a
greater debate arises from the question of “Where did life come from?”.
Indeed, it seems that this topic has not only instigated a variety of discussions
on what is the first life form on Earth, and when it appeared, but it has also
sparked a long-standing division between religion and science.
It is perplexing how a simple question has given birth to a multitude of
hypotheses that aim to present a unique explanation for Creation and the
Origin of life, whether they be supported by tangible evidences and scientific
facts or not. Nevertheless, these theories prove to be quite interesting and
refreshing studies, which will ultimately allow us to comprehend the beginning
of life.
While there have been many theories that propose its own ideas on how life
came into existence, here are some of the more popular theories, which are
still being recognized today: Patricia Lijauco

4. I. Spontaneous
Generation/Abiogenesis
Abiogenesis - or biopoiesis is the
study of how
biological life arises from
inorganic matter through
natural processes. (Abiogenesis.
(2012, February 12). In Wikipedia, The Free
Encyclopedia. Retrieved 22:03, February
13, 2012, fromhttp://en.wikipedia.org/w/index.php?ti
tle=Abiogenesis&oldid=476469737 ) Aristotle (384-322 B.C. )
Spontaneous Generation - A He proposed the theory of
popular theory that was held Spontaneous
throughout the middle ages until
Generation, when he observed
the 19th century, is the hypothesis
that some vital force contained that aphids arise from the dew which
in or given to organic matter can falls on plants, flies from putrid matter,
create living organisms from mice from dirty hay, crocodiles from
inanimate objects. rotting logs at the bottom of bodies of
http://www.microbiologytext.com/index.php?module
=Book&func=displayarticle&art_id=27 water, and so on. Abiogenesis. (2012, February 12).
In Wikipedia, The Free Encyclopedia. Retrieved 22:03,
February 13, 2012,
fromhttp://en.wikipedia.org/w/index.php?title=Abiogenes
is&oldid=476469737

5. Observations
1. mice appeared. In
Egypt, when the Nile river
flooded, along the river
fertile mud is left behind
and with it frogs
appeared.
2. In Europe, when farmers
stored their grains in
barns, molds spreads on
the grains and
3. From carcasses of meat in
the old times, flies
abound everywhere.

6. Conclusions
1. It was perfectly obvious to people
back then that muddy soil gave rise to
the frogs.
2. It was obvious to them that the mice
came from the moldy grain.
3. The rotting meat that had been
hanging in the sun all day was the
source of the flies.

7. Abiogenesis Observations
1. Put dirty shirt or some 2. A dead young
rags in an open pot or
barrel containing a few bull, was buried
grains of wheat or in an upright
some wheat bran, and
in 21 days, mice will position so that
appear. There will be its horns
adult males and protrude from
females present, and
they will be capable of the ground. After
mating and a month, a
reproducing more
mice. swarm of bees
will fly out of the
corpse.

8. Disproving Abiogenesis Theory
• Francesco Redi , an Italian
Physician in 1668 disproved
spontaneous generation for large
organisms by showing that maggots
arose from meat only when flies laid
eggs in the meat.

9. Redi’s Hypothesis & Findings
• In his hypothesis, “rotten meat does not turn
into a fly. Only flies can make more flies.”
• He found that if a flask was closed with a lid
so adult flies could not get in, no maggots
developed on the rotting meat within.
• In a flask without a lid, maggots soon were
seen in the meat because adult flies had laid
eggs and more adult flies soon appeared.

10. Redi’s Experiment

11. Disproving Redi
• 1745, John Needham • Needham theorized that if
he took chicken broth and
heated it, all living things in
it would die. After heating
some broth, he let a flask
cool and sit at a constant
temperature. The
development of a thick
turbid solution of
microorganisms in the flask
was strong proof to
Needham of the existence
of spontaneous generation

12. Disproving Needham
• Lazzaro Spallanzani
(1765) later repeated the
experiments of Needham,
but removed air from the
flask, suspecting that the
air was providing a
source of contamination.
No growth occurred in
Spallanzani's flasks and
he took this as evidence
that Needham was wrong.
Proponents of
spontaneous generation
discounted the
experiment by asserting
that air was required for
the vital force to work.

13. An End to the Conflict
• Louis Pasteur ended the debate with his
famous swan-neck flask
experiment, which allowed air to
contact the broth. Microbes present in
the dust were not able to navigate the
tortuous bends in the neck of the flask.

14. Pasteur’s Experiment

15. • The swan neck flask experiment. Pasteur
filled a flask with medium, heated it to kill all
life, and then drew out the neck of the flask
into a long S shape. This prevented
microorganisms in the air from easily
entering the flask, yet allowed some air
interchange. If the swan neck was broken,
microbes readily entered the flask and grew.

16. References:
• Abiogenesis. (2012, February 12). In Wikipedia, The Free
Encyclopedia. Retrieved 22:03, February 13, 2012, from
http://en.wikipedia.org/w/index.php?title=Abiogenesis&
oldid=476469737
• http://www.microbiologytext.com/index.php?module=B
ook&func=displayarticle&art_id=27
• http://www.newworldencyclopedia.org/entry/Origin_of
_life

17. III. Cosmozic Theory
• Also called
Panspermia Theory
• Panspermia is a
Greek word that
translates literally as
"seeds everywhere"
• It states that life
exists throughout the
Universe, distributed
by
meteoroids, asteroids
and planetoids and
that

18. Life on Earth
• Panspermia theory suggests that life was
brought to the earth via mechanisms that
include the deflection of interstellar dust by
solar radiation pressure and extremophile
microorganisms traveling through space within
an asteroid, meteorite or comet.
• extremophile microorganisms are organisms
that survive in and even may require physically
or geochemically extreme conditions that are
detrimental to the majority of life on Earth.
• These spores/microorganisms then evolved to
other organisms/living things inhabiting the
planet

19. Proponents of Cosmozoic
Theory
• Anaxagoras, a Greek Philosopher, was one
of the first to propose the concept of
Panspermia
• Berzelius (1834), Richter (1865), Thomson
(Lord Kelvin) (1871), and Helmholtz (1871)
were among the first to argue the case for
panspermia from a scientific standpoint
• Swedish chemist Svante Arrhenius (1908)
popularized the concept of life originating
from space

20. Three Variations of Panspermia
• Lithopanspermia or interstellar
panspermia
• Ballistic panspermia or interplanetary
panspermia
• Directed panspermia

21. Lithopanspermia
• Also known as interstellar panspermia
• impact-expelled rocks from a planet's
surface serve as transfer vehicles for
spreading biological material from one
solar system to another.
• Assumes microorganisms survive:
– the impact ejection process from the planet of
origin
– travelling through space, and
– landing on a planet in another solar system.

22. Ballistic panspermia
• Also known as interplanetary panspermia
• impact-expelled rocks from a planet's
surface serve as transfer vehicles for
spreading biological material from one
planet to another within the same solar
system
• Assumes microorganisms survive:
– the impact ejection process from the planet of
origin
– travelling through space, and
– landing on a planet in another solar system.

23. Directed panspermia
• Proposed by the late Nobel prize winner
Professor Francis Crick, OM FRS, along
with British chemist Leslie Orgel in 1973
• the intentional spreading of the seeds of
life to other planets by an advanced
extraterrestrial civilization, or the
intentional spreading of the seeds of life
from Earth to other planets by humans

24. Limitations of the Cosmozoic
Theory
• The theory assumes that life already exists
elsewhere in the Universe and can only explain
the appearance of life on earth. It does not
explain origin of life itself nor does it explain
how life could have originated else-where.
• It also does not necessarily suggest that life
originated only once and subsequently spread
through the entire Universe, but instead that
once started, life may be able to spread to
other environments suitable for replication

25. Gallery
ALH 84001 – meteorite found in Alan
Hills, Antartica in 1984. There are claims that
the meteorite may contain evidence of
traces of life from Mars, as images from an
electron microscope reveal chain structures
in the meteorite fragment.
(image courtesy of wikipedia.org)

26. Gallery
The surface of Mars, while mostly is a
frozen desert, have dried up channels
and crater erosion. This leads us to
believe that Mars was once warmer
and drier, and may have housed rivers
and oceans.
Was Mars once a cradle of life?
(image courtesy of wikipedia.org)

27. Gallery

28. References
• http://www.wikipedia.org
• http://www.panspermia-theory.com
• http://www.youtube.com/watch?v=AgeuRu
kfZLE
• http://www.hssrd.org/journal/summer2002/
origin.htm
• Official Nat Sci 2 Book

30. What is the Special Creation Theory About?
Unlike the other theories on the possible origin of life, the Special Creation
Theory is not supported by scientific facts or evidences. However, it is heavily
influenced by faith, specifically by one’s belief of a Supreme Being, who
created the heavens and the earth, including everything in it, from scratch.
The term “Creationism” is not limited to the Christians, as a Creationist can be
adhering to a Muslim, Buddhist, or an Islamic belief. Nevertheless, this study
will focus on the more popular notion that the Christian God is the Creator of
the universe and everything that lives within it.
In the first chapter of Genesis, which is the first book of the Bible written by
Moses, the story of Creation is narrated, from the time that the heavens and
the earth were formed until the first man was given life. In terms of the Bible’s
timeline, it is said that all of creation was created within six days. The passages
on the next slides are taken from the New International Version Bible.

41. History of the Special Creation Theory
The Special Creation Theory is basically a result of the people’s curiosity of how
life initially came to be. At that time, long before the 14th century, Creationism
has been widely accepted (though the term only became popular during the 19th
century) , most likely because of the lack of evidences and disciplines, which
focus on the disproving of this belief. This Pre-Scientific Era gave attention to
both a literal and allegorical meaning of the creation narrative in the book of
Genesis, which presented the different religions with a viable explanation on
how the world came into existence.
It was in the 14th century when the Renaissance paved the way to modern
science, which sought to disprove this theory, contributing to the development
of other theories that aim to explain when life first came into being. In spite of
the introduction of naturalism, specialization, and skepticism, the religious
groups, particularly the Protestant Reformation, strongly urged its advocates to
immerse themselves into the study of the Bible, as well as to adhere to the
conviction that God is the Creator of all things.

42. History of the Special Creation Theory
During the Renaissance era’s development of the Protoscience, it is surprising
how many scientists and philosophers have developed a study, which seek to
study Creation, by using the book of Genesis as the main guide, such as Carolus
Linnaeus’ research on the taxonomy, which he believed will reveal God’s original
plan in the creation of animal species. Disciplines like natural
theology, naturalism, and even the evolution theory first started as a simple
study to prove that the Biblical Creation story is real. It is perplexing how it
seems that religion and science support and influence one another at this
particular age.
The late 17th century brought about the Scientific era, which contributed to more
questions and arguments against the Special Creation Theory. Many scientists
questioned that if the universe and life have their beginnings and a living Creator
(as the Bible says), then surely this Creator, God, also has a beginning. As there
are no means to prove this, these people relied on their own experimentations
and researches as evidences, creating other theories about life’s origin, which
are leaning toward a scientific sense.

43. History of the Special Creation Theory
In spite of this Scientific Revolution, the Church held on firmly to its stand on the
Special Creation Theory. In 1785, geologist James Hutton introduced his ideas on
Uniformitarianism in his paper entitled, “Theory of the Earth”, which promoted
the thought that the Earth is older than 6000 years old at that time, since great
time is required to develop lands from sediments, etc. With enough evidence
and support from fellow geologists, Hutton’s eventually was accepted by the
scientific community.
By the 18th and 19th century, a compromise was made between the religious and
scientific community in the form of the Gap Theory, which accepted the six-day
creation, while still insisting that the Earth has already existed for several ages.
Charles Lyrell, clergyman and geologist, wrote the Principles of Geology series,
which supported Hutton’s Uniformitarianism, but still explained that God
created each species individually, but these creatures became extinct because of
their habitat’s evolving nature.

44. History of the Special Creation Theory
In 1859, Charles Darwin published his well-known theory of Evolution in the
Origin of Species. His work is the most famous paper, which focused on how life
forms first existed on Earth, rather than the usual researches on how Earth came
to be. The main gist of his paper is that all species has a common descent, with
man’s gradual evolution from primates as one of his main examples. Darwin’s
death in 1882 didn’t stop his followers from pursuing further studies on his
Evolution theory, in spite of the controversy that Darwin supposedly became a
Christian before he died.
The early 20th century brought new life and hope to the Special Creation
Theory, though it came not without drastic measures. Christian Fundamentalists
rejected Darwin’s Theory completely, and succeeded in banning his Evolution
ideals from being taught in schools, in the place of Genesis’ Creation and Flood
stories. This became the beginning of Darwinism’s eclipse, as many have started
to question his belief on natural selection, as well as the mechanics of evolution.
As a result, Creationism became widely accepted again.

45. History of the Special Creation Theory
Nowadays, there’s no doubt that the scientific and religious communities still
have a raging battle to prove the true origin of life, based on viable evidences
and faith in the Bible. Nevertheless, both science and religion give people the
chance to adhere to their own beliefs. Science even goes so far as to allow
people to believe in any god.
One probable reason why the Special Creation Theory has survived the test of
time is because of the equal survivability of the Bible. The traditions and
practices that the Churches have also established, in terms of studying the Bible
and looking at it in both the literal and allegorical sense, have also stayed
throughout the centuries, making the Special Creation Theory as one of the most
popular, not to mention widely accepted, theories of how life came into being.

46. How is the Special Creation Theory Acceptable?
The Special Creation Theory is widely accepted in the Christian community,
with BIBLE as the sole basis. In spite of the lack of evidences, which serve as
proof that life was created within six days, Christians have held on to their
faith, as well as to the Scriptures. Simply put, the Christian community insists
that everything you need to know about life is written in the Bible. Since the
Bible is said to be free from errors and non-contradictory, Christians have also
quoted the New Testament as to oppose those people who say that the
Creation Theory is only touched upon in the Old Testament portion.
“Through him [Jesus Christ] all things were made; without him nothing was
made that has been made.” – John 1:3 (NIV)
“.. by his Son, through whom he made the universe.” – Hebrews 1:2b (NIV)
These two verses are only two verses in the Scriptures that clearly states and
repeats that God is the Creator of everything, including man.

47. How is the Special Creation Theory Acceptable?
The Christian community also believed that God is the head of everything in
creation, including science.
“And God placed all things under his feet and appointed him [Jesus Christ] to be
head over everything for the church.” – Ephesians 1:22 (NIV)
In terms of the lack of evidence, which supports the Special Creation Theory
as true:
“We live by faith, not by sight.” – 2 Corinthians 5:7 (NIV)
“For since the creation of the world God’s invisible qualities—his eternal power
and divine nature—have been clearly seen, being understood from what has
been made, so that men are without excuse.” – Romans 1:20 (NIV)

48. How is the Special Creation Theory Acceptable?
In the logical sense, the Special Creation Theory is considered by many as a
divine miracle, which needs no further evidence or scientific support because
nobody has seen God, nor has the credibility and comprehension to
understand how He created life in general. In terms of scientific
data, Creationists will only have to look at the complicated, Biological design of
each species, which can only be created instantly by a Superior Being.
As the scientific community still continues to probe into the possibility of
evolutionary theories as the best explanation for Creation, it is surprising how
the Christian community is being patient and tolerant of science’s further
search for the truth. Christians hold on to the fact that in spite of these several
disciplines and studies, there’s still no infallible data or works that haven’t yet
been disproved, which suggests that the Special Creation Theory did not
happen. Thus, until Creationism is thoroughly disproved, it remains to be a
credible, and even scientific, explanation for the origin of life.

49. What Makes the Theory Unacceptable?
Of course, the Special Creation Theory will not remain a theory without
arguments or rejections from the scientific community. Without any scientific
evidences that will guarantee that a Supreme Being created the universe and
the life forms, then it is just not possible for Creationism to be true. For the
Creationists, the biggest foe that they’ve encountered so far are the
Evolutionists.
There are basically three main points, which the evolutionary theorists have
relied on to try and explain Creation, although these theories have been
debunked by Creationists, as well:
Fossil Evidence
In terms of the role of fossils in evolution, there has been a long-standing
debate on how an invertebrate (worm) became a vertebrate (fish) upon
fossilization. Harvard University professor, Alfred Romer, said that while this is
possible, the time it will take to do so is 100 million years.

50. What Makes the Theory Unacceptable?
Fossil Evidence (Cont.)
However, there are no records that show the invertebrates in the process of
evolution. Indeed, Stephen Stanley from Johns Hopkins University has
confirmed that not one fossil sample can support the theory of evolution, in
which a species will continue to evolve, given the right time and conditions.
Thus, it seemed that the remains were simply buried into the recesses of the
earth and preserved by minerals. This basically has the same context of
Darwin’s primate to man theory, too.
Genetics
Genetics has always been pointed as the key to evolution, since it involves the
mutation theory, which is supposed to contribute to the new creation of
species, and this is also concerned with the support of Darwin’s Evolution
Theory, by which he said that mutations happen to allow the creature to adapt
to an ever-changing environment. While this can be quite possible, particularly
because of the RNA’s ability to reproduce, scientists have failed to accept that

51. What Makes the Theory Unacceptable?
Genetics (Cont.)
evolution by mutation has its limitations, and it is not possible for the RNA
chromosome to produce other samples, which it doesn’t have. Going back to
the creation narrative in Genesis 1, it clearly said that God allowed the plants,
animals, and man to reproduce according to its kind. Therefore, the possibility
of an extraordinary genetic variation is very limited, regardless of the time or
environmental conditions.
Molecular Biology
This has basically the same thrust in evolution as Genetics, in the sense that
the scientists are pointing to the unique characteristics of a DNA structure to
change its frameworks overtime, resulting to a genetic variation, which could
ultimately produce a new species. However, instead of focusing on the actual
DNA and RNA materials, this is concerned more with the molecular activity in
the body. However, just to re-iterate, genetic variation through molecules and
atoms is limited, if not impossible.

52. What Makes the Theory Unacceptable?
The Special Creation Theory also doesn’t give the science community a
scientific explanation of the origin of life. Since this theory is completely based
on faith, thorough experimentations and researches haven’t been done to
support this belief. Plus, those who’d be willing to do such experiments will
find it impossible to do so because it’s not possible to measure God as a
subject, as well as the precise environment at that time.
As far as the scientific community is concerned, it is perfectly okay for some to
accept the Special Creation Theory out of faith. Nevertheless, this will not stop
them from trying to find out the truth about existence.

53. References
• http://www.noanswersingenesis.org.au/creation_model_is_unscientific.htm
• http://en.wikipedia.org/wiki/Creation%E2%80%93evolution_controversy
• http://en.wikipedia.org/wiki/History_of_creationism
• http://plato.stanford.edu/entries/creationism/
• http://www.parentcompany.com/csrc/basics.htm
• http://www.bibarch.com/concepts/origins/creation.htm
• http://www.smashinglists.com/top-10-theories-on-beginning-of-life-on-
earth/
• NatSci2 Biology Book

54. II. Biogenesis Theory

55. • The history of Earth and its life are
two concepts that are inseparable.
Researchers and scientists in different
disciplines of science are still
debating about the history of Earth
and how and where life originated
(Campbell et al., 1999). Many
theories about the origin of life on
Earth were formulated throughout
the years. However, the validation of
the said theories can be difficult
because life is incessantly evolving.

56. Solar Nebula Theory or Nebular
Hypothesis
• This theory is the most accepted widely accepted theory that explains the
formation and evolution of the solar system (Coffey, 2010). The said theory was
first proposed in the 18th century by Immanuel Kant, Emanuel Swedenborg and
Pierre – Simon Laplace. In 1755, Kant disputed that gaseous clouds—
nebulae, which slowly rotate, gradually collapse and flatten due to gravity and
eventually form stars and planets. Laplace’s proposed a similar model in which a
protosolar cloud (a nebular cloud) contracted and cooled, flattening and
shedding rings of material in the process which later collapsed to form the
planets. Laplace proposed in his text, “The System of the World”, in 1796 a
similar model in which a protosolar cloud (a nebular cloud) contracted and
cooled, flattening and shedding rings of material in the process which later
collapsed to form the planets. Over the course of the 20th century, this model
came to be challenged by a number of theorists who proposed numerous
models in an attempt to replace it. However, none of these attempts were
successful and it was not until the 1970’s with Soviet astronomer Victor
Safronov that the modern (and widely accepted) Solar Nebular Disk Model
(SNDM) came into being (Williams, 2010).

57. • The key idea behind the solar nebula hypothesis is that once a rotating
interstellar gas cloud has commenced gravitational collapse, then the
conservation of angular momentum will force the cloud to develop a
massive, central condensation that is surrounded by a less massive flattened
ring, or disk of material. The nebula hypothesis asserts that the Sun forms
from the central condensation, and that the planets accumulate from the
material in the disk. The solar nebula model naturally explains why the Sun is
the most massive object in the solar system, and why the planets rotate
about the Sun in the same sense, along nearly circular orbits and in
essentially the same plane (Net Industries, 2012).

58. The stages of solar nebula theory
• Originally a large cloud of dust and gas
(75% H and 24% He) became unstable.
The densest part of the cloud started
to collapse under the force of gravity
Gravity pulled the dust and gas toward
the center of the cloud, causing the
cloud to take on a spherical shape.
• As the size (radius) of the cloud
decreased, the collapsing cloud
increased its rate of rotation. The
principle on which this conclusion is
based is a law of physics called “the
conservation of angular momentum”.
The effect is similar to that of an ice
skater who must pull in his or her arms
in order to increase his or her rate of
spin.

59. • The increased rotation of the cloud caused the cloud to change shape. It became flattened at the
rotational poles. Thus the once spherical cloud became disk shaped. This rotating disk of dust and gas
became the “solar nebula”. Most of the matter in the collapsing cloud ended up in a central bulge
• As the cloud collapsed, gravitational energy was released, heating the central portion of the nebula
where a protosun formed.
• Meanwhile, condensation was occurring within the disk surrounding the protosun. Because temperatures
within the disk varied with distance from the center of the nebula, different materials condensed at
different locations within the disk. Closer to the center, where temperatures were high, high temperature
condensates such as iron and silicates formed. Farther from the center, where temperatures were
low, hydrogen, water and other low temperature condensates formed.
• Collisions between the newly condensed particles caused larger bodies called planetesimals to accrete.
This accretion process continued eventually forming the planets and moons. This violent and cataclysmic
process of planetary formation is today evidenced by the cratered surfaces of Mercury and our Moon.
The recent collision between comet Shoemaker-Levy and Jupiter also gave us a glimpse at what probably
happened on a much grander scale when the solar system was very young.
• The heat generated by these impacts and by radioactive decay of elements resulted in molten planets
which subsequently became differentiated.
• The evolving star at the center of the solar nebula passed through a T-Tauri star at which point it released
bursts of energy. These bursts swept light elements such as hydrogen out of the outer solar system and
into the outer solar system where it is swept up by the distant jovian planets.
• The young protosun got hot enough to ignite the hydrogen its core. Thermonuclear reactions in the core
are what distinguish a “sun” from a protosun.
• The terrestrial planets evolved their secondary (Venus and Mars) and tertiary (Earth) atmospheres.

60. Miller – Urey Experiment
This experiment is
conducted in 1953 by
Stanley Miller under
the supervision of
Harold Urey; the first
experiment to test the
Oparin-Haldane
theory about the
evolution of prebiotic
chemicals and the
origin of life on Earth.
Figure 1. The Miller – Urey
experiment

61. • A mixture of methane, ammonia, hydrogen, and water vapor, to simulate
the version of Earth's primitive, reducing atmosphere proposed by Oparin,
was introduced into a 5-liter flask and energized by an electrical discharge
apparatus to represent ultraviolet radiation from the Sun. The products
were allowed to condense and collect in a lower flask which modeled a
body of water on the Earth's surface. Heat supplied to this flask recycled
the water vapor just as water evaporates from lakes and seas, before
moving into the atmosphere and condensing again as rain.
• After a day of continuous operation, Miller and Urey found a thin layer of
hydrocarbons on the surface of the water. After about a week of operation,
a dark brown scum had collected in the lower flask and was found to
contain several types of amino acids, including glycine and alanine,
together with sugars, tars, and various other unidentified organic
chemicals (The Encyclopedia of Science, N.D.).

62. From Coacervates to Heterotrophs
to Autotrophs

63. Formation of Complex Organic
Compounds
• The smaller and simpler organic compounds that were formed initially in the
earth, gradually started combining among themselves to form complex organic
compounds. Simple sugars combined among themselves to form complex
polysaccharides such as starch and cellulose. Fatty acids and glycerol
molecules combined to form lipids. Amino acids combined among themselves
to form polypeptides and proteins. Purines and pyrimidines combined with
simple sugars and phosphates to form nucleotides, which in turn combined to
form nucleic acids. Heat of the sun probably provided the energy required for
the formation of complex organic compounds.
• Haldane suggested that due to the accumulation of complex organic
molecules, the sea ultimately became a sort of 'hot, dilute soup' where in, the
molecules collided, reacted and aggregated to form more complex molecules.

64. Formation of Molecular Aggregates
• It is suggested that the large organic molecules formed abiotically in the primitive
earth came together spontaneously and due to intermolecular attraction, formed
large colloidal aggregates called Coacervates. An envelope of water molecules
formed around each such aggregate due to the hydrophilic nature of some of
these compounds. A membrane of fatty acids protected and enclosed these
molecules, increasing the chances of chemical reactions. Gradually, breakdown
and building up reactions started for which the energy required was provided by
the breakdown reactions. The coacervates selectively absorbed proteins and other
materials from the ocean resulting in their active growth. The coacervates not only
started growing rapidly but also started multiplying.

65. Formation of First Cells (Protobionts)
• The coacervates were in a state of dynamic equilibrium, constantly taking in new materials
from the oceans and releasing degraded materials. Thus, they had all the basic properties of
life such as metabolism, growth and reproduction. However, they lacked the complexity of
molecular organization, catalytic proteins (enzymes) and precise control of nucleic acids.
Later, the nucleic acids are said to have taken control of coacervate and the process of
replication became precise in the due course of time. With the nucleic acids being
established as the genetic material, the coacervates got transformed into the primitive living
systems which have been called as protobionts or eobionts.
• Some of the proteins in protobionts are said to have developed the ability to catalyse
chemical reactions, thereby functioning as the first enzymes. The formation of enzymes
greatly enhanced the rate of synthesis of various molecules in the protobionts.
• In the course of time, the protobionts became enclosed by a protein lipid
membrane, allowing the accumulation of some molecules and the exclusion of others. This
property improved the ability of protobionts to survive and compete with others. With the
processes of metabolism, growth and reproduction becoming regular, precise and
regulated, the first cells or organisms were formed. The termprogenote has been suggested
by Carl Woese to describe the first cell which served as the ancestor of all the forms of life
existing today.
• The first forms of life developed among the organic molecules, in the oxygen free
atmosphere. Hence, they presumably obtained energy by the fermentation of organic
compounds. They were heterotrophs, requiring ready-made organic compounds as food.

66. • Chemoheterotrophs-They were prokaryotic like bacteria. They were anaerobes.
They must have been dependent on the organic molecules present in the broth for
body building and obtaining energy.
• Chemoautotrophs-They were unable to synthesize organic molecules from
inorganic raw materials, with the help of chemical energy obtained by the
degradation of chemical compounds present in the sea.
• Photoautotrophic-The next step was to development of pigment molecules
chlorophyll. It would absorb solar energy and convert it into chemical energy. This
process is termed as photosynthesis. The earliest formed organisms were
photoautotrophic bacteria. They were anaerobic and did not produce O2 as
byproduct during photosynthesis, because they did not use water as a reagent.

67. Aerobic Photoautotrophs
• They evolved 3300 to 3500 million
years ago. They were like present day
cyanobacteria and could release
O2 into the atmosphere because they
used water as the reagent. Thus, the
whole reducing atmosphere changed
to an oxidising atmosphere.
• Autotrophs are said to have arisen
much later in the primitive earth due
to a mutation in the primitive
heterotrophs. The appearance of
autotrophs, particularly photo
autotrophs changed the situation.
The appearance of photosynthetic
organisms resulted in the release of
free molecular oxygen into the
atmosphere gradually transforming it
into an oxidizing type from the
existing reducing type

68. Adaptation Modes for Survival
• 1. Nutritional Adaptation
• The first primitive cells called premonera were believed to be basically aquatic
and heterotrophs, which derived food from their environment. Some of them
most probably exhibited mutations in their nucleic acids. The nature of the
mutations should have led to the development of new metabolic reactions which
eventually led to the evolution of autotrophs (Rivero & Cao, 2005).
• Autotrophs – organisms that have the capacity to produce their own food from
an inorganic source of carbon through photosynthesis (light) or chemosynthesis
(chemical) (Campbell et al., 1999).
• Photosynthesis - is the process of converting light energy to chemical energy and
storing it in the bonds of sugar (Carter, 1996).
• Chemosynthesis - is the process by which certain microbes create energy by
mediating chemical reactions.

69. 2. Structural Adaptation
• The first heterotrophs and autotrophs were in all probability prokaryotic, simple
one – celled organisms. Bacteria and cyanobacteria are present day prokaryotes.
Eukaryotes are believed to evolve from prokaryotes through endosymbiosis and
invaginations (Rivero & Cao, 2005).
• Endosymbiosis - a type of symbiosis in which one organism lives inside the other,
the two typically behaving as a single organism. It is believed to be the means by
which such organelles as mitochondria and chloroplasts arose within eukaryotic
cells.
• Invagination - an infolding of the outer layer of cells of an organism or part of an
organism so as to form a pocket in the surface, as in the embryonic development
of a gastrula from a blastula.

70. The Domains of Life

71. • The three-domain system, which classifies life on the planet into three different
domains - Archaea, Bacteria and Eukaryote, was put forth by American microbiologist
and physicist Carl Woese in 1990. Basically, it is a biological classification of the three
domains of life based on the differences in their 16S rRNA genes. Other popular
biological classification systems include the two-empire system - also referred to as
the super-domain system, and the six-kingdom system.
• Archaea Domain: Archaea are prokaryotic cells which are typically characterized by
membranes that are branched hydrocarbon chains attached to glycerol by ether
linkages. The presence of this ether containing linkages in Archaea adds to their ability
of withstanding extreme temperature and highly acidic conditions. Extreme halophiles
- i.e. organisms which thrive in highly salty environment, and hyperthermophiles - i.e.
the organisms which thrive in extremely hot environment, are best examples of
Archaea.
• Bacteria Domain: Even though bacteria are prokaryotic cells just like Archaea, their
membranes are made of unbranched fatty acid chains attached to glycerol by ester
linkages. Cyanobacteria and mycoplasmas are the best examples of bacteria. As they
don't have ether containing linkages like Archaea, they are grouped into a different
category - and hence a different domain. There is a great deal of diversity in this
domain, such that it is next to impossible to determine how many species of bacteria
exist on the planet.

72. • Eukarya Domain: Eukaryote are eukaryotic
cells which have membranes that are
pretty similar to that of bacteria. Eukaryote
are further grouped into Kingdom Protista
(algae, protozoans, etc.), Kingdom Fungi
(yeast, mold, etc.), Kingdom Plantae
(flowering plants, ferns, etc.) and Kingdom
Animalia (insects, vertebrates, etc.). Not all
Eukaryotes have a cell wall, and even if
they do they don't contain peptidoglycan
as bacteria do. While cells are organized
into tissues in case of kingdom Plantae as
well as kingdom Animalia, the presence of
cell walls is only restricted to the members
of kingdom Plantae.
• Each of these three domains of life
recognized by biologists today contains
rRNA which is unique to them, and this fact
in itself forms the basis of three-domain
system. While the presence of nuclear
membrane differentiates the Eukarya
domain from Archaea domain and Bacteria
domain - both of which lack nuclear
membrane, the distinct biochemistry and Figure 3, The three
RNA markers differentiate Archaea and domains of life
Bacteria domains from each other

73. The Five Kingdoms of Life within the
Domain Eukarya

74. Sources:
• http://faculty.ccbcmd.edu/courses/eas101/unit1/solneb.html
• http://science.jrank.org/pages/6265/Solar-System-solar-nebula-hypothesis.html
• http://www.universetoday.com/72589/solar-nebula-theory/
• http://www.universetoday.com/77525/nebular-theory/
• http://www.daviddarling.info/encyclopedia/M/MillerUreyexp.html
• http://www.tutorvista.com/content/biology/biology-iii/origin-life/origin-life-
steps.php
• http://www.usc.edu/org/cosee-
west/Nov30_2011/Three%20domains%20of%20life.pdf
• http://biology.clc.uc.edu/courses/bio104/photosyn.htm
• http://www.pmel.noaa.gov/vents/nemo/explorer/concepts/chemosynthesis.html
• http://www.google.com.ph/imgres?q=solar+nebula+theory&hl=tl&gbv=2&biw=1
024&bih=634&tbm=isch&tbnid=186RqGCM1DLz2M:&imgrefurl=http://abyss.uor
egon.edu/~js/ast121/lectures/lec24.html&docid=ECKtxgQ277dXZM&imgurl=http:
//abyss.uoregon.edu/~js/images/nebular_hypothesis.gif&w=565&h=527&ei=NVN
ET8i2C8aQiQednd2TAw&zoom=1

75. VI. RNA World Theory

76. RNA World Theory
• Darwin's theory on natural
selection implied that all current
life-forms could have evolved from a
single, simple progenitor which is
referred to as the 'last' common
ancestor. One feature is the presence
of genetic information and the
means to replicate and carry out
those heritable instructions for
functioning and reproducing. In
addition, the system for replicating
genetic material had to allow for
some random variation in the
heritable characteristics of the
offspring so that new traits could be
selected and lead to the creation of
diverse species

77. • Another commonality is that all living
things consist of similar organic (carbon-
rich) compounds. Also, the proteins
found in present-day organisms are
fashioned from one set of 20 standard
amino acids. Furthermore, all
contemporary organisms carry their
genetic information in nucleic acids -
RNA and DNA - and use essentially the
same genetic code. From these findings,
we can infer that the last common
ancestor stored genetic information in
nucleic acids that specified the
composition of all needed proteins. It
also relied on proteins to direct many of
the reactions required for self
perpetuation. The question now
becomes where does the proteins and
nucleic acids come from?
Image Credit: DNA

78. Got to Start Somewhere
In 1983, Thomas R. Cech and Sidney
Altmanindependently discovered
the first known ribozymes,
enzymes made of RNA,
indicating that the ancient RNA
may have been catalytic.
However, no RNA molecules that
direct the replication of other
RNA molecules have been
identified in nature. In the mean
time, Cech and Jack W. Szostak
have modified naturally
occurring ribozymes so that they Thomas R. Cech Sidney Altman
can carry out some of the most
important subreactions of RNA
replication, such as stringing
together nucleotides or
oligonucleotides.

79. The Chicken and Egg problem (nucleic
acids and proteins)
• Nowadays nucleic acids are synthesized only with the help of
proteins, and proteins are synthesized only if their
corresponding nucleotide sequence is present. It is
extremely improbable that proteins and nucleic acids, both
of which are structurally complex, arose spontaneously in
the same place at the same time. Yet it also seems
impossible to have one without the other. The paradox is
resolved by the RNA world - a world in which RNA catalyzed
all the reactions necessary for the precursor of life's last
common ancestor to survive and replicate. The RNA could
subsequently have developed the ability to link the amino
acids together into prteins. For the RNA world to exist, RNA
needs the capacity to replicate without the help of proteins
and an ability to catalyze every step of protein synthesis.

80. Why RNA is favored over DNA as the
originator of the genetic system
• The ribonucleotides in RNA • In an experiment, Szostak
are more readily synthesized created a pool of random
than are the oligonucleotides to
deoxyribonucleotides in DNA. approximate the random
It is easy to envision ways production presumed to have
that DNA could evolve from occurred some 4 billion years
RNA and then, being more ago. From that pool, he was
stable, take over RNA's role as able to isolate a catalyst that
the guardian of heredity. could join together
Researchers suspect that RNA oligonucleotides. Also, the
came before proteins because catalyst could draw energy for
they face difficulty composing the reaction from a
any scenario in which triphosphate group, the very
proteins could replicate in the same group that now fuels
absence of nucleic acids. most biochemical reactions in
living systems.

81. • To explain how self-replicating RNA was
created from its constituents, it is
hypothesized that the nucleotides in RNA
formed when direct chemical reactions led to
joining of the sugar ribose with nucleic acid
bases and phosphate. Then, these
ribonucleotides spontaneously joined to form
polymers, at least one of which happened to
be capable of engineering its own
reproduction.

82. From Molecules to Organism
In the late 1990s Jim Ferris and his
coworkers
at the Rensselaer Polytechnic
Institute
showed that clay minerals enhance
the process,
producing chains of up to 50 or so
nucleotides.
(A typical gene today is thousands
to millions of
nucleotides long.) The minerals’
intrinsic ability
to bind nucleotides brings reactive
molecules
close together, thereby facilitating
the formation
of bonds between them

83. RNA Breeding Grounds
RNA Breeding GroundS
After chemical reactions created
In the water solutions in which the first genetic building
they formed, nucleotides
blocks and other organic
would have had little chance of molecules, geophysical
combining into long
processes brought them to new
strands able to store genetic environments and
information. But under the
concentrated them. The chemicals
right conditions—for example, if assembled into more
molecular adhesion
complex molecules and then into
forces brought them close primitive cells. And
together between microscopic
some 3.7 billion years ago
layers of clay (above)— geophysics may have also
nucleotides might link up into
nudged these “protocells”to
single strands similar to modern reproduce.
RNA.

84. Journey to the modern cell
• If a piece of RNA codes for a particularly good
protein then there is nothing to stop that
protein being used by other RNA molecules
• If however the RNA is enclosed in a
membrane then it can keep it’s protein to
itself and gains a selective advantage
• So membranes probably pushed evolution by
natural selection forwards

85. • The phospholipids form lipid bilayers when
they are surrounded by water
• All the components of a simple prokaryotic
cell were now assembled
• They diversified in their metabolism
• By 2 billion years ago free oxygen was
appearing in the atmosphere due to the
activity of photosynthetic bacteria

86. • References :
http://www.talkorigins.org/faqs/abioprob/or
iginoflife.html
• http://www.scientificamerican.com/article.cf
m?id=origin-of-life-on-earth