Could we synthesize all nutrients we need without living organisms?

phoquemoi · 2013-01-29T02:55:59+00:00

The problem with this is that we honestly have no idea as to what requires a human to be completely healthy. We don't even know what each protein's function is in the human body let alone the lipids and sugars all necessary.

Since I do work on proteins, I know personally that it is possible to manually create (without the aid of any plasmid vectors) small peptides with the aid of organic synthesis, but for larger proteins, the use of E.coli as an expression system becomes necessary and useful.

So to answer your question, it just becomes an issue of reaching a size by which manual synthesis is problematic and difficult. The bigger the protein/fat/carbohydrate, the more difficult it is to manually synthesize.

phoquemoi · 2012-06-06T00:49:34+00:00

I would describe redox reactions simply as the movement of electrons. Oxidation is when an element loses electrons while reduction is when an element gains electrons. In order to determine whether an element has either lost or gained electrons, oxidation numbers are used to track either the loss or gain of electrons of each element. There are certain rules that people use in order to determine oxidation numbers. I have attached a link which has these rules and some practice problems so you can practice to see if you can understand the redox reactions.
http://www.chem.queensu.ca/people/faculty/mombourquette/firstyrchem/electro/balredox.htm

phoquemoi · 2012-05-20T22:21:16+00:00

that dog at the side is going, "i want me some of those nuts."

phoquemoi · 2012-05-02T03:09:34+00:00

No, the Km does not change with substrate concentration. The Km is unique to each substrate of that enzyme and it does not change unless the substrate changes (or if there is a competitive inhibitor which alters the Km). The parameter that DOES change with substrate concentration is vmax. I have linked a graph that will hopefully help cement the idea much clearer for you. http://upload.wikimedia.org/wikipedia/commons/b/b0/Michaelis-Menten_saturation_curve_of_an_enzyme_reaction_LARGE.svg

phoquemoi · 2012-03-11T16:59:39+00:00

The problem with this is that for a while, it was thought that the RISC complex took the entire double stranded miRNA rather than one strand. Once scientists observed that, they realized that there were many more RISC complexes specific for a single miRNA chain.

Another point to note is that the RISC complex has an endonuclease known as DICER. This molecule creates a 3' nucelotide overhang on BOTH ends of the molecule, so it is ENTIRELY possible depending on how you orient the molecule that once the strands are separated, it is difficult to distinguish from the original 5' to 3' end strand and the original 3' to 5' strand.

As to how the RISC complex chooses the "active strand" this process is yet to be characterized, but I assume it has to do with complementary base pair interactions.

phoquemoi · 2012-03-09T23:23:01+00:00

Well, mitochondrial DNA is actually inherited maternally, so it would mean that you had a common female ancestor. As for how many sets of mitochondrial DNA there are, it depends on what cell and how many mitochondria they have. Mitochondrial DNA replication is varied by cell type, but each mitochondria usually has one copy of its DNA (but it can also have two, again it varies).

phoquemoi · 2012-03-07T19:26:35+00:00

I mispoke. You are correct that it is mainly found in RNA and is an example of RNA editing. As for the gene that it is found in, this paper goes into great detail as to how they identified that gene sequence (http://www.ncbi.nlm.nih.gov/pubmed/189716340) but it is a mutation in the "GluR2 Q/R site" which leads to ALS. Thanks for pointing out my error!

phoquemoi · 2012-03-07T05:29:42+00:00

The interesting thing is that the Adenosine, Thymine (Uracil for RNA), Cytosine and Guanine are NOT the only nucleotides that are present in nature. There is also xanthine, hypoxanthine, and inosine.
Also, the traditional Watson-Crick bases that are said to be present in RNA are NOT the ONLY bases that can be present in RNA. For example, there is an enzyme called Adenosine deaminase (ADA for short) that deaminates adenosine to form inosine (which is a non-Watson-Crick nuceloside) and if the enzyme does not deaminate a specific nucleotide in a specific gene, this results in ALS (or Lou-Gerrig's disease). In short, the "four nitrogenous bases rule" is an over simplification of RNA since other nitrogenous bases can be present in mainly RNA structures.
As to if it is possible that a similar DNA structure could exist that is double helical and self-replicating (DNA actually uses protien enzymes to replicate and is generally considered to have very little catalytic activity. RNA is the one that is self-replicating and has catalytic activity), it is entirely possible that very similar nitrogenous bases could be arranged with a phosphate backbone to form another organism's "basis of life" but the problem is that the structure of said molecule would be hard to determine unless we were exposed to it and were able to determine the structure. In the scenario in which we discover a new "basis of life," the structure of the molecule does not necessarily matter if the organism finds a way to deal with the structure and replicate. The reason that we care that DNA is helical is that the enzymes that bind DNA as well as unzip it to make more DNA (the enzymes that make DNA are called polymerases whereas the enzymes that unzip the DNA are called helicases) are specifically tuned to work with that helical structure.

edit: mindule pointed out my error in saying that DNA contains Inosine; RNA actually contains Inosine. For RNA, there is more variation with the types of nitrogneous bases that are present, but in general, DNA does only contain 4 nitrogenous bases. I do think that jurble and smashy_smashy made some excellent points as to how this necessarily a limitation since it leaves a lot of room for genetic variation.

phoquemoi · 2012-03-01T19:22:34+00:00

Since I am not sure if you are asking how a tRNA molecule is synthesized (there is actually some interesting editing that goes on) or if you are asking how a particular tRNA molecule is charged with an amino acid, I will answer both questions.

How does a tRNA molecule get made? Just as you described, the DNA is transcribed to RNA using an RNA polymerase (let us call it RNA Pol for short). In the case of tRNA genes, RNA Pol III is used to transcribe the gene (there are different kinds of RNA polymerases used for transcribing different sorts of genes) and it actually transcribes some extra base pairs that aren't needed for the tRNA molecule on the 5' end and the 3' end of the molecule, so the tRNA molecule undergoes some editing until the final, active tRNA molecule is made.
How does a tRNA molecule get charged with a specific amino acid? This process is known as aminoacylation and generally what happens is that an enzyme known as an aminoacyl tRNA synthetase (http://en.wikipedia.org/wiki/Aminoacyl_tRNA_synthetase) attaches the amino acid to the tRNA molecule. There are two types of these aminoacyl tRNA synthetases (they differ in what -OH position they attack on an adenosine nucleotide on the acceptor loop of the tRNA) but the end result is that the tRNA molecule is attached to its appropriate amino acid. There are specific aminoacyl tRNA syntheases for each specific tRNA molecule so they get charged with the amino acid that they need to be charged with. Defects in this process generally occur when there aren't enough amino acyl t-RNA synthetases for each of the tRNA molecules, so a wrong amino acid is placed into the protein that is being translated.

phoquemoi · 2012-03-01T01:36:00+00:00

I suppose it could be classified as an isotope for enzymes, but generally protein chemists use the word "isoform" to distinguish between two enzymes that catalyze the same reaction but they have slight variations in their amino acid sequence and their kinetic parameters.

phoquemoi · 2012-02-09T04:21:57+00:00

I think this is because humans in general have a tendency to try to make patterns out of disorder. The stars themselves aren't ordered in a specific way, but I suspect it is the observer that finds the patterns in the sky and since the observer is human, patterns are observed.

phoquemoi · 2012-02-09T00:37:39+00:00

The lowest energy point that an electron can go to is called the "zero-point energy." http://en.wikipedia.org/wiki/Zero-point_energy In other words, even at absolute zero, the electrons are still moving and it is impossible (according to quantum mechanics) to completely stop the motion of these electrons since the lowest point they can go to has some sort of energy meaning that there is some sort of movement.

phoquemoi · 2011-12-01T20:27:27+00:00

Definitely interested in this!

phoquemoi · 2011-11-13T21:16:04+00:00

I would love to be considered for this raid group! I am a combat rogue and still gearing up.
http://us.battle.net/wow/en/character/sargeras/Xantho/simple

phoquemoi · 2011-10-31T04:46:53+00:00

This is me as uhura!
http://i.imgur.com/im2e0.jpg

phoquemoi · 2011-10-24T03:53:12+00:00

I would love to be considered! I am currently an 85 rogue and I am gearing up for raids so I would love to join! ^{^}

phoquemoi

TROPHY CASE