Wednesday, August 31, 2011

Notes: Hadean Eon and the Origin of Life on Earth

How did the Earth form? In a nutshell their was a supernova around 5,000,000,000 (5 B.Y.A.)  years ago which cuased the interstellar dust cloud to begin to spin and collapse onitself becuase of its own gravity, the heat from their collision and the intense pressure created the sun.  Further out other particles started to come to gether and grew bigger and bigger and became the planets.    Click the link to get a better idea.

The Hadean is the geologic eon before the Archean. It started with the formation of the Earth about 4.6 billion years ago (4,600,000,000) and ended roughly 3.8 billion years ago, The name "Hadean" derives from Hades, Greek for "Underworld", referring to the "hellish" conditions on Earth at the time.

Oldest rock on Earth: approximately 3.8 billion years ago.  That means we have almost 800,000,000 years the is virtually unrecorded in the History of the Earth.  On the coast of Hudson Bay in northern Quebec are dated from 3.8 to 4.28 billion years old.

Earth's Oldest Fossil: are the stromatolites consisting of rock built from layer upon layer of sediment.   Stromatolites from the late Archean and through the middle Proterozoic eon were mostly formed by massive colonies of cyanobacteria (formerly known as blue-green "algae"), and that the oxygen byproduct of their photosynthetic created earth’s oxygen rich atmosphere about 2.2 billion years ago. 

Theories of How Life First Evolved On Planet Earth

The supposed development of living organisms from nonliving matter. Also called autogenesis, spontaneous generation

Watch this video by Carl Sagan expalining the Miller Experiment.

Meteorite Theory:
Panspermia: Panspermia is a Greek word that translates literally as "seeds everywhere". The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may have originated through these "seeds".

Tuesday, August 30, 2011

Amino Acids - The Building Blocks of Life

What are amino acids?
Amino acids  are the building blocks of proteins and play an essential role in metabolism.

Humans can produce 10 of the 20 amino acids. The others must be supplied in the food. Failure to obtain enough of even 1 of the 10 essential amino acids, those that we cannot make, results in degradation of the body's proteins—muscle and so forth—to obtain the one amino acid that is needed. Unlike fat and starch, the human body does not store excess amino acids for later use—the amino acids must be in the food every day.

What are proteins?

Proteins are macromolecules. They are constructed from one or more unbranched chains of amino acids. A typical protein contains 200–300 amino acids but some are much smaller  and some much larger.

Every function in the living cell depends on proteins therefore they also depend on amino acids.  
•Motion and locomotion of cells and organisms depends on proteins. [Examples: Muscles, Cilia and Flagella]
•All biochemical reactions are done by enzymes, which contain protein.
•The structure of cells, and the extracellular matrix in which they are embedded, is largely made of protein. [Examples: Collagens] (Plants and many microbes depend more on carbohydrates, e.g., cellulose, for support, but these are synthesized by enzymes.)
•The transport of materials in body fluids depends of proteins. [See Blood]
•The receptors for hormones and other signaling molecules are proteins.
•Proteins are an essential nutrient for heterotrophs.
•The transcription factors that turn genes on and off to guide the differentiation of the cell and its later responsiveness to signals reaching it are proteins.
• and many more — proteins are truly the physical basis of life.

Amazing DNA Video

This video is a bit complex but it really is quite stunning.

Notes on the Miller Urey Experiment - On the origin of life.

Mr. S Summarizes.

SO these dudes made an experiment on some gasses and water and found that by adding electricity they could essentially create the building blocks of life.  Later researchers confirmed this finding and then some finding they could produce the components of DNA from non living gasses by adding electricity. 

As well researchers have found meteorites that have amino acids still in them which indicates that possibly life was brought to earth by falling meteorites.  Which makes me think....where did their life evolve...still the same question.

It is also important to note that the atmosphere of early earth (4.5-3.8 billion years ago) was nothing like it is today.  Humans could not have survived.  There was little to NO oxygen in the atmosphere.

We know that there are single celled organisms that don't need oxygen to survive.  They are called anaerobic.

 adapted from

1950 - Tried to see if they could create life from gases and electric current.

They used  molecules which were believed to represent the major components of the early Earth's atmosphere and put them into a closed system

The gases they used were methane (CH4), ammonia (NH3), hydrogen (H2), and water (H2O). Next, he ran a continuous electric current through the system, to simulate lightning storms the researchers observed that some of the carbon formed of organic compounds. More amazingly some had formed amino acids which are used to make proteins. Finally and more importantly still their experiment showed that amino acids, which are essential to cellular life, could be made easily under the conditions that scientists believed to be present on the early earth. This enormous finding inspired a multitude of further experiments.

In 1961, Juan Oro discovered that from an aqueous solution he could produce the nucleotide base, adenine. Adenine is of tremendous biological significance as an organic compound because it is one of the four bases in RNA and DNA. It is also a component of adenosine triphosphate, or ATP, which is a major energy releasing molecule in cells. Further experimentation showed that the other essential components of DNA and RNA could be created  through prebiotic chemistry.

On September 28, 1969, a meteorite fell over  Australia, analysis of the meteorite has shown that it is rich with amino acids. This meteorite has demonstrated that the Earth may have acquired some of its amino acids and other organic compounds by meteorite striking earth.....but then where did they get their amino acids from?

Tuesday, August 23, 2011

Welcome back - 1st blog assignment - Origin of Life

I am very excited to be your science teacher and share with you my joy for scientific inquiry and thinking. There is so much we can learn from the field of science and yet so much to be discovered. Let the journey begin.

Your first blog assignment is click, read,  and then comment about this link to the  Miller/Urey Experiment on the origin of life on planet Earth.

A few sentences is enough of a response.  What do you think?  Do you understand what they are saying?  What questions do you have?

Please use write your paragraph in a word document so you can spell check it before cutting and pasting it into the blog.

Make sure never to leave your full name.