NOVA "Origins" How Life Began

For what percentage of Earth's history have multicellular forms of life existed?

10%

For what percentage of Earth's history had no life?

24%

How long ago did the Earth begin?

4.5 billion years

How many people were on Earth when this video was made in 2004?

6 billion

For what percentage (period) of Earth's history did microbes rule?

66%

Which chemical out of H, O, C, and N is the "star of the show?" Why?

C because it forms more bonds with more elements, including itself, than any other element.

What gases predominated in the early Earth's atmosphere?

CO2 and HS4 (hydrogen sulfide)

What are "snotites?"

Colonies of single-celled bacteria, that are producing their own food by chemosynthesis by using HS4.

What is the significance of snotites and phlegm balls as we discuss early life on Earth?

Early life on earth needed the HS4, and the discovery of the snotites and phlegm balls backs up the beginnings of our Earth by billion of years. We also know that life can live in toxic areas (whole habitats).

What 4 chemicals are the common elements of all life on Earth?

H (hydrogen), O (oxygen), C (carbon), N (nitrogen)

What are "phlegm balls?"

Same as snotites, but in a ball form under water.

Hydrogen sulfide can turn into what acid?

Sulfuric acid in the presence of water or water vapor.

Rocks which are 3.8 billion years old were examined in Greenland for the forms of carbon which are left behind by living organisms. Why couldn't scientists just look for the organisms, rather than for the "chemical fingerprint" of the carbon left by the organisms?

The heat and pressure rocks go under destroys fossils over time.

This build-up of oxygen from the photosynthesis of cyanobacteria also produced what layer in our atmosphere? What is the significance of this layer to life on Earth?

The ozone screens out ultra violet radiation, though some chemicals break threw this layer.

What happened with the experiment which simulated the pressure of meteorite striking amino acid molecules? Why is this significant?

The pressure sped up the development of life on Earth. Amino acid molecules did not break down but help form more complex bonds. (peptides turn to proteins)

What was the "Heavy Bombardment?" What happened and what were the effects?

There were 600 million years of bombardment of astroids and comets. The effects were liquified rock and vaporized oceans.

Microbes have been discovered deep within the Earth's crust in mines in South Africa. How are these microbes surviving?

They are surviving on the energy of methane, ethane, and propane (chemosynthesis), which are all gases and considered toxic to life.

What is the significance of amino acids?

They are the building blocks of proteins.

What are stromatolites? How are they significant to the study of how life began on Earth?

They are the oldest fossils (3.5 billion years old) known. They are made of microbes that photosynthesize and are the reason that humans are on this planet (photosynthesize = oxygen). They helped us realize that life evolved earlier and faster than we first thought.

Once the Heavy Bombardment eased, microbes could migrate to the surface of the Earth. Once on the surface, how could they obtain energy?

They obtained energy from the chlorophyl which trapped the sunlight and went through the process of photosynthesis. The ocean was filled with water until it was saturated and then it evaporated into the atmosphere.

Microbes have been discovered in vents in the depths of the ocean. How are these microbes surviving?

They use the energy from hydrogen sulfide coming out of hydrothermal vents. Hydrogen sulfide makes sugars by chemosynthsizing, which makes the microbes producers.

There are more than 70 kinds of --- --- in meteorites.

amino acids

What do we use iron ore for?

any large building and cars

Iron oxide particles settled to the bottom of primordial oceans over millions of years to produce what deposits?

iron ore (produces when its warm b/c of photosynthesis)

About 3.5 million years ago, oxygen combined with iron which was being spewed from volcanoes to produce what compound?

iron oxide (rust; all red dirt and stone is from iron oxide)

The building blocks of life may have come from ---. "Space" begins about --- kms. from Earth's surface.

outer space and 20

What was the surface of early Earth like?

It was covered in lava.

From 3.5 billion to 5760 million years ago, oxygen built up in Earth's atmosphere from less than 1% to 21%, where it remains to modern day. Why is this such a significance event?

Now larger organisms and larger animals are alive.

What did stromatolite cyanobacteria produce which was a byproduct of photosynthesis?

Oxygen, which helped with the rapid development of life and bigger organisms.