Beginning Of Life On Earth

Beginning of Life on Earth
Question 1
a) What is one of the suggestions for the beginning of life on Earth? What is the problem with this idea?
The article states that suggestions have been made that germs of life may have made their way to Earth from outer space. This may have occurred due to comet dust resting on the Earth's surface. Another theory proposed by Francis Crick states a spaceship sent out by a distant civilisation may have contained the first signs of life. The issue with these ideas is that no evidence has been obtained in support of these proposals, nor is there a reason to support these theories anymore due to substantial evidence that life did in fact start on the Earth itself.

b) What similarity existed between Urey-Miller's experiment and the Murchison meteorite?
The similarity that existed between Urey-Miller's experiment and the Murchison meteorite is the presence of similar amino acids in the same relative proportions. The Urey-Miller experiment aimed to determine how lightning could have possibly affected the atmosphere of the primitive Earth. The results showed that over just a few days, a variety of amino acids had formed from carbon methane subjected to electrical discharges. It is these same amino acids obtained via the Urey-Miller experiment that have been discovered in the Murchison meteorite. This suggests the results of the experiment are highly relevant.

c) What are the main functions of proteins and nucleic acids (DNA)? What is a significant difference between these molecules?
Proteins and DNA are two of the earliest biological molecules and have significant importance in the function of the modern cell. Proteins act as the structural and functional factors in the cell. Structural proteins build different components inside of a cell and around it. Catalytic proteins serve to break down food and retrieve/consume energy. Regulatory proteins oversee the expression and replication of genes, enzyme performance, interaction of cells and their environments, among many other purposes. DNA however acts a storage capsule for genetic information and also the code for creation of proteins. DNA determines how amino acids are strung together to form an organism's proteins. The significant difference between these two molecules is that protein is incapable of replicating itself. They rely on the self-replication of DNA to produce more proteins.

d) What do you think the phrase "Life is a cosmic imperative" means? Do you agree? Why or why not?
The phrase "Life is a cosmic imperative" means that the beginning of life itself was not a matter of chance, but was inevitable and bound to happen. I agree with this statement as there are too many specific steps taken in order to create life. The article states that "a string of improbable events - the same lottery number being drawn twice .. does not happen naturally", which is another reason I believe that life being inevitable is true. It may have been by chance that the conditions suitable for life were brought together by chance, but the series of events that occurred to create this suitable environment are far too specific to simply be attributed to chance.
Question 2
a) Describe a "black smoker".
A black smoker is a kind of hydrothermal vent located on the far depths of the ocean floor. They are much like cracks in the surface of the Earth where water that has been heated under the Earth's surface escapes from. These black smokers are most often found near active volcanic hotspots such as diverging tectonic plates. They are given their name from the black smoke-like emissions of particle-laden fluids from the seafloor vents.

b) Why are these "black smokers" important?
Black smokers are the supporting system of a vast variety of sea life in an environment absent of sunlight. The immense combination of toxic chemicals, high pressure, high temperatures and total darkness made researchers believe it was not possible for life to be supported in this environment. Studies have revealed the vast array of life living in these areas, called Extremophiles, such as bacteria. These life forms help determine under which range of conditions life is possible. Black smokers also hold vast ore deposits on the sea floor because of dissolved minerals in the brines of the vents as they pass to the surface of the ocean floor. In the future it may be viable to mine these ore deposits as land ore deposits are being depleted rapidly. These underwater ore deposits may prove to be vital in the future.

c) Life forms

Question 3
Six stages to the process of chemosynthesis
1. The first phase of chemosynthesis occurred in the primitive Earth, where random molecules in the atmosphere came together to form simple organic molecules such as amino acids, with energy provided by UV radiation and other light sources.
2. These simple molecules that formed in the first phase now come together to form major organic macromolecules, such as amino acids bonding to form proteins.
3. These macromolecules that formed in the second phase are organised into different bodies with a defined shape and other properties that closely resemble living organisms.
4. With the fourth phase comes the appearance of nucleic acids that control reproductive process and directed the internal activities of early cells, the first signs of life.
5. The fifth phase is the start of evolutionary development through natural selection based on genetic ability to reproduce the fastest.
6. Autotrophic bacteria appears in the sixth phase which are self-sufficient organisms that could synthesise nutrients by utilising energy from the sun.

Question 4
a) What are Archaea? What environments do these organisms live in?
Archaea are a group of organisms discovered in the 1970s. These bacteria live at high temperatures, with some living at temperatures far beyond 100oC. They are often found inside the digestive systems of cows and marine life where they produce large clumps of methane. Archaea are considered some of the only organisms capable of living in such extreme habitats of incredibly hot or salty water.