Transcript life.

The big bang you’ve all
heard about was a
huge “explosion” that
distributed matter
and energy
throughout our
universe, about 15
billion years ago.
The Eagle Nebula
As seen through Hubble Telescope
A nursery in space
This is the raw materials
that stars are made of.
We are made of stardust!
Our sun and solar system
being born some 4.6 billion
years ago.
How life originated on Earth has
fascinated and intrigued humanity for
as long as we have had the capacity to
think on a higher level.
Many answers have been proposed, but
still the mystery remains.
Let’s review some of the most common
of these beliefs, and inferences.
The Mid-Ocean Ridge is the
longest mountain chain on the
Earth. It is an area where the
Earth’s crust is expanding.
Black smokers deep within the
Atlantic Ocean near the midocean ridge.
Earth's atmosphere was a reducing one,
chock full of methane, ammonia, hydrogen
and water vapor.
The first forms of life were prokaryotic
in nature, and by necessity, they were
anaerobic.
These early methanogens (methane-producers)
used the available elements (hydrogen, helium,
sulfur…etc) in a sort of “chemosynthesis”
process, creating simple carbohydrates in much
the same way our photosynthesizing organisms do
today.
The oxygen in the atmosphere today comes mainly from
plants and microorganisms such as algae. (Cyanobacteria)
• oxygen given off, CO2 taken up
• More organisms photosynthesizing…more O2 in
our atmosphere
• from reducing to oxidizing to ozone…
If liquid water had not accumulated, membranes
which take on their bilayer organization only in the
presence of water could not have formed.
= phosphate
= lipid
No membrane, no cell.
Life at its most basic level
is the cell, which has the
capacity to survive and
reproduce on its own.
In the presence of this
“reducing” atmosphere, energy
from the sun, volcanoes, and
lightning caused chemical
reactions among these gases,
which eventually combined
into small organic molecules
such as amino acids.
Rain trapped these
atmospheric molecules and
carried them to the oceans,
making a primordial soup of
organic molecules.
Once in this “soup” the proteins, lipids, and complex
organic molecules found in present-day cells, formed.
Next, diversification occurs (aka
adaptive radiation or divergent
evolution). Some cells developed
that became metabolically capable
of photosynthesis. This caused a
cascade of irreversible events,
(called the G.O.E.) interconnected
by biogeochemical cycles.
It is important to realize that the first
organisms on Earth could not have relied
on the Sun’s energy (photosynthesis), or
an oxygen-rich atmosphere, which is
precisely why we study the hydrothermal
vent community along the Mid-Oceanic
Ridge.
In the 1950s the great
scientific race to solve the
puzzle of life’s origins was
on.
The Miller-Urey experiment
featured an apparatus into which
was placed a reducing gas
atmosphere thought to exist on
the early Earth. The mix was
heated up and given an electrical
charge and simple organic
molecules were formed.
While they didn’t create life, so to speak, they did provide
evidence to support the “primordial soup” theory in that
they produced organic molecules out of the mixture.
•Amino acids (building blocks of proteins)
Other experiments were successful at producing
glucose, ribose, deoxyribose, and other sugars
What are the organic molecules that must
have been present for early life to begin?
• amino acids: to form proteins
• sugars (which are a part of nucleotides)
A nucleotide is three things: a nitrogenous
base; a sugar; and a phosphate group.
• Fatty acids (lipids)
Some scientists think that the formation of self-replicating molecules
such as DNA and RNA came before living cells.
RNA probably predates DNA on Earth. RNA is more
complex than the protein it codes for, and it is not as
complex as DNA, scientists think it must have predated
DNA.
DNA is far more
efficient at
packing in more
coding information
for the production
of proteins, and it
is quite a bit more
sophisticated than
RNA.
Spontaneous formation of lipids, carbohydrates, amino
acids, proteins, and nucleotides under abiotic conditions
Formation of proteinRNA systems, and DNA
evolution
Formation of lipid spheres
Protein Synthesis and self-replication
became possible through
transcription of DNA and
translation of RNA
Membrane-bound proto-cells
The
cellular life
Firstfirst
true-living
cells
One scientific hypothesis about the origin of life on Earth is that the
molecules necessary for life arrived here on meteorites, rocks from
space that collide with Earth’s surface.
meteorites contain atmospheric
gases trapped in shock melted
minerals
Many meteorites
contain organic
matter. These organic
molecules, which are
necessary for the
formation of cells,
might have arrived on
Earth and entered its
oceans.
Scientists today have
used meteorites to help
determine the original
Earth’s atmosphere.
This theory proposes that cellular organelles originated as bacterial cells
that developed a symbiotic relationship with other cells. (host-anaerobe
/ symbiont-aerobe)
The early aerobic
prokaryotes which were
ingested, resisted digestion
in their “host”, and thrived.
So, mitochondria originated
as a bacterium
Ribosomes originated as a
bacterium
We find accidental partnerships in nature all the time. Some
species spend their entire lifetime inside the host species.
Buchnera aphidicola are obligate endosymbionts of aphids
E. Coli are endosymbionts within human intestines
Life as we don’t know it
The discovery of bacteria that use a different
chemical building block in its structure stretches the
scientific definition of "life."
So what???
Even though doubt has been cast upon the
experiment that led to the arsenic-based life
discovery in Lake Mono, scientists are
searching for other evidence on Earth to
find “critters” that are and have been here,
and we just haven’t noticed them because
we are so focused on life that is similar to
us. Perhaps life has been present on Earth
for far longer than we expect.
What might life based upon silicon look
like?
Can a person “believe” in scientific theories?
The answer can only be, “No.” The fact that the Earth is
very old and life has changed over billions of years is
scientifically valid”, because that is what the evidence tells
us.
Science is not about belief (based on faith)—it is about
making inferences based on evidence.
A person may, however, believe in Divine Origins, as is the case with
95% of human cultural groups on the planet. Religion is faith based,
whereas science seeks universal truths based on experimental findings,
that have been tested and tested over and over again. This is not
necessary in religion, because of “FAITH”.
Problems do occur when one tries to use “religion” to explain scientific
phenomena, or use “science” to explain religious phenomena. (ie,
intelligent design)
Let’s look at several creation stories, and determine the
difference between “belief, and inference”.
Common to all human cultures throughout history is the belief that life
on Earth did not arise spontaneously, but through divine intervention.
All creation stories
have themes in
common.
• A birth
• Mother/Father
images
• A supreme being
• A supreme place,
either above or
below