Origin of Life:

by Chance or by Design?

By -

• Swati Agarwal - 2884

• Ayush Jain - 2888

Zoology Hons. 1st Year (SectionA)

Hansraj College Delhi University

The Nature of Life• Life

– During last 4 by adapted to many environments and physico-chemical conditions

– Most organisms live at 1 atm and 0-40oC; Some Bacteria can live up to 1400 atm or -18 to 104oC

– Unicellular Organisms vs Non Living Molecules (Amino acids, RNA (ribonucleic acid)• reproduction• growth via nutrients and energy• responds to outside stimuli• Share same genetic code• chemical uniformity

– C, O, H, N, P >> nucleic acids, proteins, carbohydrates, fats

• Prokaryote vs. Eukaryote– small (1-10 um) vs large (10-100um)– No nucleus vs Nucleus– DNA in nucleoid vs Membrane bounded nucleus

containing chromosomes made of DNA, RNA– Cell division direct (binary fission) vs mitosis and

miosis– Rare multicellular forms vs Multicellular organism

with extensive development of tissues

Building Blocks: Pattern shared by all life

• All Life: DNA => RNA => Protein• DNA architect plans for building (instructions to build

proteins in the ribosome) transcribes information into RNA (Blueprint)

• RNA messenger translates blueprint into proteins in the ribosomes

• Genes code for specific proteins (enzymes)• Enzymes are proteins that control all chemical reactions• Order of nitrogenous bases (read in groups of 3) {A, T, C,

G} determines the type of proteins made• Each group of 3 codes for a specific amino acid

DNA: Our Genetic Code

Spiral double helix of sugars and phosphate linked together by nitrogenous bases such as Thymine, Cytosine, Adenine and Guanine.

A Gene is a portion of the DNAmolecule that includes approximately 1500 base pairs and a Chromosome contains many genes

The Origin of Life• 19th Century Ideas

– life created supernaturally• cannot be proven scientifically

– continually being formed by spontaneous generation of nonliving matter• untenable by numerous experiments

• 20th Century– life generated spontaneously and

evolved through different steps

The Origin of Life• Origin of life is NOT an event • Origin of life is a continuous process• Stages

– inorganic production of key simple organic molecules– production of more complex molecules that can synthesize more

of the same molecule– development of a genetic code of self-replicating molecules

(RNA,DNA,proteins)– production of the first cell by separation of these codes from the

outer world by a membrane

• Ocean environment by 4.0 by- fossils evident at 3.8by

The Origin of Life• Many complex organic molecules must have

formed before an organism produced• The process of life took many steps over the

first 600 my• Probability theory would dictate that at least

one random event would have produced a result

• This process cannot occur on Earth today because the simple organism would be destroyed by oxidation or predation

Steps in the Origin of Life

• Aerobic vs. Anaerobic– oxygen poisons living cells so early life was anaerobic

• Lack of free Oxygen >> No Ozone layer– UV radiation kills cells so life had to originate at depth– Water depths of 10m or more

• Models– non-oxidizing secondary atmosphere rich in the

constituent chemicals for life--H2O, CO2, N

– Energy in the form of UV radiation & Hot springs

Steps in Origin of Life• Before the first cell>>Chemical Evolution

– production of significant molecules necessary for life

• Phosphoric acid crucial to cell chemistry>> phosphoric acid can bond molecules and promote long chain molecule formation

• Amino acids formed first since they do not form if oxygen present– probably formed on clay surfaces since they are attractive and

absorptive, also protection from UV

• Larger Molecules– amino acids are linked together by dehydration synthesis (water

loss), clays have potential to absorb water, thus amino acids could be linked on clay surfaces

Experimental Studies• A. I. Oparin- 1930s

– Produced sugars and fatty acids from the constituents of an early atmosphere

• Urey and Miller- 1953– Production of cyanide, formaldehyde and 4 different amino

acids from water vapor, methane, hydrogen and ammonia and electrical sparks

• Subsequent Experiments– Production of 18 of the 20 known amino acids and extremely

simple forms of DNA from gases rich in water vapor, CO2, and nitrogen and UV radiation

– S.W. Fox (1959) produced protein-like (protenoids) chains from a mixture of 18 amino acids at 70oC in the presence of phosphoric acid

The Environment for Life • Volcanic Hot Springs• Oceanic hydrothermal

vent system• Deep (below the level of

UV penetration)• Clays and/or Zeolites as

templates• Similarity with present

day chemosynthetic heterotrophic organisms

Oparin, Haldane, 1930’s

Autobiogenesis

Spontaneous Origin of Life

BiologyG.B.Johnson and R.H.Raven, 1996

BiologyBiggs et. al.Glencoe Pub. 2004.Chap 14.2

Biochemistry D. Voet & J.G. Voet Wiley 2004

Electricalenergy

SunlightHeat

Simple Cells

Proteins and

nucleic acids

Molecules of aspartic acid with a left-handed orientation, shown in crystal form, could be the "ancestral Eve" of all amino acids -- the building blocks of proteins -- in life on Earth.

The Origin of Life and the Crystallization of Aspartic Acid in Water

Tu Lee* and Yu Kun LinDepartment of Chemical

and Materials Engineering, National Central University,Taiwan, R.O.C.Cryst. Growth & Design 2010

“The landing site of the Mars rover Curiosity was once covered with fast-moving and possibly waist-high water that could have possibly supported life, NASA scientists announced Thursday.”

Star Tribune Sept 28, 2012

Oparin, Haldane, 1930’s

Autobiogenesis:

Spontaneous Origin of Life

Haldane, J. B. S. (John Burdon Sanderson) (1892–1964) known as Jack (but who used 'J.B.S.' in his printed works), was a British-born geneticist and evolutionary biologist. A staunch Marxist, he was critical of Britain's role in the Suez Crisis, and chose to leave Oxford, move to India and become an Indian citizen. He was one of the founders (along with Ronald Fisher and Sewall Wright) of population genetics.

Alexander Oparin(1894-1980)The influence of the Marxist theoretical concept of dialectical materialism, part of the Communist Party's official interpretation of Marxism, fit Oparin's definition of life as 'a flow, an exchange, a dialectical unity'. This notion was enforced by Oparin's association with Lysenko.

Stanley Miller, 1953

Chemistry graduate student at University of Chicago

General formula for amino acids

Table 1-4 Yields from Sparking Mixture of CH4, NH2 , H2O and H2

Oparin, Haldane, 1930’s

Autobiogenesis:

Spontaneous Origin of Life

Research into 1970’s supportive

First photograph ever taken from the surface of Mars. Viking 1 Lander July 20, 1976.

Primary objectives of the Viking missions - obtain high-resolution images of the Martian surface, - characterize the atmosphere and surface - search for evidence of life on Mars.

http://grin.hq.nasa.gov/ABSTRACTS/GPN-2003-00061.html

“…recent advances…have thrown serious doubts on the anoxic [oxygen free] model…”

—H. Clemmey and N. Badham“Oxygen in the precambrian atmosphere: An evaluation of the geological evidence.”

Geology 10(3), 145 (March 1982).   

“No geological or geochemical evidence collected in the last 30 years favors a strongly reducing primitive atmosphere…Only the success of the laboratory experiments recommends it.”

—R.A. Kerr“Origin of life: new ingredients suggested.”Science 210(4465), 42 (October 3, 1980).

Oparin, Haldane, 1930’s

Autobiogenesis:

Spontaneous Origin of Life

Can Random Reactions Produce a Protein?

Typical proteinN = 100-300

How many ways to arrange 100 amino acids, 5 of each type?

W = # arrangements = !!!

!

2021 nnn

N

10115 different peptides <105 useful for life

115

20 10!5

!100

!5!5

!100

Can Random Reactions Produce a Protein?

How long will it take to create a particular polypeptide?

vs.

10115 possible structures

(1041)(1014 rearrange/s)(1017s) = 1072 polypeptides

fastest chemical reaction age of Earth?

Maillard Reactions Degrade Proteins

Oparin, Haldane, 1930’s

The Enigma of the Origin of Life

“The largest stumbling block in bridging the gap between nonliving and living still remains. All living cells are controlled by information stored in DNA, which is transcribed in RNA and then made into protein.

This is a very complicated system, and each of these three molecules requires the other two--either to put it together or to help it work. DNA, for example, carries information but cannot put that information to use, or even copy itself without the help of RNA and protein.”

Kenneth R. Miller and Joseph Levine, Biology: The Living Science (Upper Saddle River, New

Jersey: Prentice Hall), 1998, p.406-407.

The First Cells• All cells use the same genetic code• Archaeobacteria- most primitive

– Heterotrophs: obtain energy from surroundings by some chemical reaction

– Obtain energy by converting CO2 and H2 to CH4 or by the reduction of sulfur compounds

• Eubacteria– 10 Phyla, including cyanobacteria (Autotrophs: manufacture

their own food source)

• First Cells poorly developed metabolic systems– absorbed nutrients directly– fermentation

Life• Prokaryota

– Appear 3.8-3.6 by– no nucleus– single loop chromosome with all genes– reproduction-binary fission

• Eukaryota– Single cell appear 2 by– Multicellular appear as trace fossils 1by and as body fossils

700my– Nucleus with 2 pairs of chromosomes (2 copies of all genes)– Asexual and SEXUAL reproduction>> more combinations

Did life arise on another planet?

Theory of Panspermia –

Hoyle and Wickramasinghe 1980’s

Stanley Miller:

the chemical origin of life is a lot more difficult than we first imaged

Father of 'Origin of Life’Chemistry Dies

May 21, 2007

National Geographic 1998

• Antony Flew, a British philosophy professor and leading champion of atheism for more than half a century, changed his mind and became a deist at the age of 81.

• He said it was a result of “my growing empathy with the insight of Einstein and other noted scientists”

• In an interview with ABC News Flew indicated that a "super-intelligence is the only good explanation for the origin of life and the complexity of nature."

Did life begin by chance or by design?

– Huge amount of information in the molecules of life

– No naturalistic theory for origin of life– We know that intelligence can create molecules of

life– Design is not an argument from ignorance

– Is a “super intelligence the only good explanation for the origin of life (A. Flew)” ?

The world looks more complex to a scientist.

The world looks more beautiful to a scientist.

Science teaches humility.

This comes from an understanding of what we do not know.

Belief in a Creator has energized the greatest scientists.