Saturday, April 11, 2009
Universal Code
On page 75, Carrroll writes "Much to our convenience, but also of profound evolutionary significance, this code is, with few minor exceptions, the same in every species (this is why bacteria can be used to produce human proteins for pharmaceutical use, such as insulin)." Explain in your own words, using outside sources as reference, the significance of the code for proteins being the same in every organism. Also find examples of other organisms used to produce other proteins and the significance of those manufactured proteins.
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It is important for us to notice the universal code because it supports the core theme of biology, which is evolution. The fact that we see the same multiple genes in many different organisms supports the fact that once, there really was the Last Universal Common Ancestor, from which all life has evolved.
ReplyDeleteFrom the genetic code, we can deduce that all life has evolved from a single cell. Since genes are recipes for making proteins, we can compare our genetic code or proteins to other organisms to determine that all organisms evolved from LUCA. Interestingly enough, as Sean Carroll says, the exact same code is used in humans and bacteria to make protein. This is why we can put human gene into bacteria and copy multiples of them.
Now, I believe that I made it clear enough why those universal codes are important to many biologists and scientists. For many years, many biologists tried to reconstruct LUCA. Based on the fact that every organisms share certain codes, I believe it is simple enough for biologists to compare different branches of tree of life such as : Eukarota, bactera, and archaea to find out the characteristics of LUCA. However, the truth is that it is not that simple. As time passes on, some genes get lost and some genes get swapped. That is the fundamental process of Evolution. As we evolve, we lose some traits while we may gain new traits: we are just fine tuning according to changing environment to survive and thrive.
After many years of study, biologists have figured out a way to determine how old a gene is and how genes get transferred. They found out a way to check if a gene is ancient or not is by figuring out if the gene code is recipe for protein or RNA. This is an important clue because some RNAs date back to an even earlier period than the time when LUCA lived. However, as biologists studied on, they found another possibility.
Carl Woese, one of the key players in the reconstruction of LUCA said: LUCA was in to gene swapping, and on a much larger scale than what we observe in modern bacteria, and that “gene swapping was once more important than inheritance from parent to offspring” which suggests that there never was a single LUCA, but more of a community of genes loosely associated with cells. Obviously, nothing is certain at this point. However, one thing that Universal code guarantees is that there once was Luca, which all organisms evolved from.
. Also find examples of other organisms used to produce other proteins and the significance of those manufactured proteins.
In addition, an example of other organisms used to produce other proteins would be insulin. Insulin is a hormone which helps to store glucose in to liver, muscle and fat tissue cells as glycogen. When control of insulin levels fails in the body system, people get diabetes. In the early years, humans didn’t have synthetic human Insulin. However, scientists have found a way to help people suffering from diabetes. They just obtained insulin from cows, pigs or salmon. This is possible because the protein sturcutre of insulin was all similar which supports the existence of Universal code and eventually the existence of LUCA. :D
http://www.carbs-information.com/insulin-synthetic.htm
http://www.actionbioscience.org/newfrontiers/poolearticle.html
DNA’s universal language is the most prominent evidence supporting evolutionary theory, allowing every organism to be characterized by the same four-character protein recipe book and linking all genetic makeup together, suggesting that everything must spring from the last universal common ancestor.
ReplyDeleteA closer look at the characteristics of the LUCA can identify not only how different organisms evolved from the universal cook book but examines the nature of the original. Going back to the fundamentals, the codes for protein are made up from adenine, guanine, cytosine, thymine in DNA, and uracil in RNA, combined with a phosphate and deoxyribose or ribose (RNA) group. Through thermodynamic experiments, it’s been proven that the precursor molecules CH2O and HCN under hydrothermal factors, called the strecker synthesis, can synthesize these nucleobases and monosaccharides. This supports the theory that organic can come from inorganic, and provides a clue to justify spontaneous generation, life emerging from inanimate material, and solving the biogenesis paradox. This explains why these characters would exclusively tell the language for proteins, because their synthesis can spring from nonlife.
LUCA is generally perceived to be a single common ancestor that all life has evolved from. This would help explain why the code is universal, but as Carroll only briefly mentions, this conjecture is flawed.
(continued)
ReplyDeleteThere are notable exceptions to the ‘universal’ genetic code for proteins, http://www.pnas.org/content/95/24/14584.2.full.pdf, such as in animal mitochondria, where AUU codes for Met instead of Ile, or a more species-specific example, in nuclear blepharisma where UAG codes for Gln instead of STOP. This anomaly in animal mitochondria is significant because mitochondria share properties similar to other prokaryotes, which suggest that they were once prokaryotes themselves that were engulfed by another cell through endocytosis. If mitochondria were once prokaryotes, that puts them much closer to the LUCA while still maintaining significant deviations in their interpretations of genetic code. This supports the hypothesis that LUCA was not a simple primitive hyperthermophilic prokaryote but something with a more complex community.
Some scientists go as far as to hypothesize that the LUCA was something more of a protoeukaryotic organism that adapted to a broad range of temperatures and was morphologically and metabolically diverse. This claim offers the explanation that life went from complex to simple to complex, starting with the unknown but eukaryotic-like LUCA, which through redundant evolution created prokaryotes, which then much later gave rise to eukaryotes again. This theory would offer an explanation on why the genetic code isn’t universal in absolute.
Carroll himself stresses (in italics) that “understanding the meaning of the similarities and differences” is the key to evolution, and the differences in mitochondrial DNA and other exception are significant clues that shouldn’t be overlooked.
Nonetheless, the presence of a LUCA is enough to explain why the code for proteins is the same for almost every organism and further solidifies evolutionary principles. This is advantageous because manufactured proteins are compatible with all organisms.
An example of this can be found in a treatment for thyroid deficiencies such as hypothyroidism, an autoimmune disease in which the body’s immune defenses destroy the thyroid. An alternative ‘natural medicine’ answer for this can be found in Armour thyroid, which contains desiccated thyroid derived from the thyroid gland of a pig which can be given in a pill.
http://www.biology-direct.com/content/3/1/29
http://www.springerlink.com/content/aq10866526v08u65/
http://www.all-creatures.org/mfz/health-thyroid-20090118.html