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Glycolysis and Alcoholic Fermentation

Glycolysis (from glycose, an older term for glucose + -lysis degradation) is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+. The free energy released in this process is used to form the high-energy compounds ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide).Yeast cells obtain energy under anaerobic conditions using a very similar process called alcoholic fermentation,  also referred to as ethanol fermentation, is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products.

Glycolysis requires 11 enzymes which degrade glucose to lactic acid (Fig. 2). Alcoholic fermentation follows the same enzymatic pathway for the first 10 steps. The last enzyme of glycolysis, lactate dehydrogenase, is replaced by two enzymes in alcoholic fermentation. These two enzymes, pyruvate decarboxylase and alcoholic dehydrogenase, convert pyruvic acid into carbon dioxide and ethanol in alcoholic fermentation.

The most commonly accepted evolutionary scenario states that organisms first arose in an atmosphere lacking oxygen.1,2 Anaerobic fermentation is supposed to have evolved first and is considered the most ancient pathway for obtaining energy. However, there are several scientific odds against that.

First of all, it takes ATP energy to start the process that will only later generate a net gain in ATP. Two ATPs are put into the glycolytic pathway for priming the reactions, the expenditure of energy by conversion of ATP to ADP being required in the first and third steps of the pathway (Fig. 2). A total of four ATPs are obtained only later in the sequence, making a net gain of two ATPs for each molecule of glucose degraded. The net gain of two ATPs is not realized until the tenth enzyme in the series catalyzes phosphoenolpyruvate to ATP and pyruvic acid (pyruvate). This means that neither glycolysis nor alcoholic fermentation realizes any gain in energy (ATP) until the tenth enzymatic breakdown.

Enzymes are proteins consisting of amino acids united in polypeptide chains. Their complexity may be illustrated by the enzyme glyceraldehyde 3-phosphate dehydrogenase, which is the enzyme that catalyzes the oxidation of phosphoglyceraldehyde in glycolysis and alcoholic fermentation. Glyceraldehyde phosphate dehydrogenase consists of four identical chains, each having 330 amino acid residues. The possible number of different combinations of these amino acid chains is infinite.

 

Glyceraldehyde-3-phosphate dehydrogenase

 

To illustrate, let us consider a simple protein containing only 100 aim acids. There are 20 different kinds of L-amino acids in proteins, and each can be used repeatedly in chains of 100. Therefore, they could be arranged in 20^100 or 10^130 different ways. Even if a hundred million billion of these (10^17) combinations could function for a given purpose, there is only one chance in 10^113 of getting one of these required amino acid sequences in a small protein consisting of 100 amino acids. By comparison, Sir Arthur Eddington has estimated there are no more than 10^80 (or 3,145 x 10^79) particles in the universe! Consider the 10 enzymes of the glycolytic pathway. If each of these were a small protein having 100 amino acid residues with some flexibility and a probability of 1 in 10^113 or 10^-113, the probability for arranging the amino acids for the 10 enzymes would be: P = 10^-1,130 or 1 in 10^1,130, and this result is only the odds against producing the 10 glycoytic enzymes by chance. It is estimated that the human body contains 25,000 enzymes. If each of these were only a small enzyme consisting of 100 amino acids with a probability of 1 in 10^-113, the probability of getting all 25,000 would be (10^-113)^25,000, which is 1 chance in 10^2,825,000…

Figure 2

 

 

There are still other problems with that theory. There are numerous complex regulatory mechanisms which control these chemical pathways. For example, phosphofructokinase is a regulatory enzyme which limits the rate of glycolysis. Glycogen phosphorylase is also a regulatory enzyme; it converts glycogen to glucose-1-phosphate and thus makes glycogen available for glycolytic breakdown. In complex organisms there are several hormones such as somatotropin, insulin, glucagon, glucocorticoids, adrenaline thyroxin and a host of others which control utilization of glucose.

In addition, complex cofactors are absolutely essential for glycolysis. One of the two key ATP energy harvesting steps in glycolysis requires a dehydrogenase enzyme acting in concert with the “hydrogen shuttle” redox reactant, nicotinamide adenine dinucleotide (NAD+). To keep the reaction sequence going, the reduced cofactor (NADH + H +) must be continuously regenerated by steps later in the sequence (Fig. 2), which requires one enzyme in glycolysis (lactic dehydrogenase) and another (alcohol dehydrogenase) in alcoholic fermentation.

Further, at one point, an intermediate in the glycolytic pathway is “stuck” with a phosphate group (needed to make ATP) in the low energy third carbon position. A remarkable enzyme, a “mutase” (Step 8), shifts the phosphate group to the second carbon position—but only in the presence of pre-existent primer amounts of an extraordinary molecule, 2,3-diphosphoglyceric acid. Actually, the shift of the phosphate from the third to the second position using the “mutase” and these “primer” molecules accomplishes nothing notable directly, but it “sets up” the ATP energy-harvesting reaction which occurs two steps later!

 

by Jean Sloat Morton, Ph.D.

 

References

1 A.I. Oparin, Origin of Life, New York: Dover Pub., lnc., 1965, pp. 225-26.
2 (Jark and Synge (eds.), The Origin of Life on the Earth, New York: Pergamon Press, 1959, p. 52.
3 Ernil Borel, Probabilities and Life, New York: Dover Pub., Inc., 1962, p. 28.

 

Cite this article: Morton, J. S. 1980. Glycolysis and Alcoholic Fermentation. Acts & Facts. 9 (12).

From: http://www.icr.org/article/glycolysis-alcoholic-fermentation/

 

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Is Water the Solution to how Life began?

Is Water the Solution to how Life began?

From: EarthAge


Although water is portrayed by many as the solution to, or star player in how life came to be, the fact is that water spontaneously breaks down complex molecules that living organisms need to exist: such as DNA,* RNA, proteins and their components.**   For example, an article on Molecular Cloning says that  
Proteins are usually soluble in water solutions because they have hydrophilic amino acids on their surfaces.”1

Amino acids have been called the building blocks of life, and when two or more are joined together they are called a peptide and the bond that holds them together is called a peptide bond.  When ten or more are linked together they may be called a polypeptide, and if they are ordered and folded correctly, they become a protein.  And in a wikipedia article on peptide bonds we are told that a peptide bond can be broken by … hydrolysis” ***  (just by) … “adding … water” … (and that the) “… bonds in proteins are metastable, meaning that in the presence of water they will break spontaneously.” 2

Another article on this topic 3  says that hydrolysis is:

“A chemical reaction in which water is used to break the bonds of certain substances. In biotechnology and living organisms, these substances are often polymers …such as that … (exist) between two amino acids in a protein … “

Dr. A. E. Wilder-Smith, (Ph.D. organic chemistry) also brought this out in a book he wrote on life’s complexity and origin.4

“Amino acids and other building blocks present in the macromolecules of living matter aggregate to form larger units … by … (a reaction) called condensation.****  The combinations usually involve the elimination of one molecule of  water between two combining molecules.  It is the removal of this molecule of water which presents the major difficulty  …  For, the removal of this water molecule from between two combining molecules requires energy which must … be supplied in some fashion.

“A further difficulty arises in this question of the elimination of water.  For, in the prebiotic world, it is assumed that the condensation reaction took place in the presence of a large … (supply) of water which would tend, according to the law of mass action, to hinder the condensation process and … (promote) decomposition(or breakdown of peptides and polypeptides). … The more water, the less condensation.”

“If the reaction is to proceed in the direction of the dipeptide, (or two amino acids that are joined together) … the water molecule … (that results) must be removed from the reaction system since the reaction is reversible.  If it is not removed … (it will) hydrolyze (or separate) the dipeptide back again to the constituent amino acids …”

This means the “primordial soup,” or “warm little pond”  where Darwin speculated that life began could not have been simply water, since it would “hydrolyze” or break down complex molecules back into their basic original amino acid as soon as they formed.  Dr. Charles McCombs explains the problem as follows in an article he wrote on the subject of whylife by chance  is virtually, if not utterly and completely impossible.  

“Every time one component reacts with a second component forming the polymer, the chemical reaction also forms water as a byproduct …  There is a rule of chemical reactions … called the Law of Mass Action that says all reactions proceed in a direction from highest to lowest concentration. This means that any reaction that produces water cannot be performed in the presence of water. This Law of Mass Action provides a total hindrance to protein, DNA/RNA, and polysaccharide formation because even if the condensation took place, the water from a supposed primordial soup would immediately hydrolyze them. Thus, if they are formed according to evolutionary theory, the water would have to be removed … which is impossible in a “watery” soup.5

But because the “watery soup” in living cells is surrounded by a membrane, the “water” inside the cell “behaves very differently”  than ordinary water.  In fact, the “water” in a cell is not water but a blend of water, amino acids, proteins, and many other chemicals called cytosol. This mixture is the result of the DNA’s ability to regulate what goes in and out of the cell — via  numerous channels that control and regulate what is allowed to pass through the cell membrane, and thus to create and maintain a favorable environment and PH for DNA, RNA and protein synthesis, and life itself to exist. 

If the concentration of amino acids is high enough, some of them will link up with others to form dipeptides and tripeptides.  An article on this subject states that:

It is important to recognize that by whatever reactions polymerization (or the joining of amino acids) occurred, they had to be reactions that would occur in an essentially aqueous environment. This presents difficulties because condensation of amino acids to form peptides, or of nucleotides to form RNA or DNA, is not thermodynamically favorable in aqueous solution.”{6}

The explanation for this is partly that the concentration of amino acids decreases as amino acids form pairs (called dipeptides) in a solution. This decreased concentration causes the velocity of the peptide synthesis reaction to slow down, and some dipeptides begin breaking up, again becoming single amino acids.The solution reaches equilibrium when just as many dipeptides dissociate as associate. A very tiny fraction of the dipeptides add another amino acid to form a tripeptide. … Oligopeptides (Oligo=few) and polypeptides (poly=many) will form only very rarely. Tripeptides dissociate faster than dipeptides in the same solution. 7

In this regard, a tripeptide has only three amino acids, while the simplest protein ever found has at least eight, that are all connected in a specific order.

Jeffrey P. Tomkins makes the following statement in a book on the design and complexity of the cell:

“… plasma membranes are … quite complex and … (function) as more than just a barrier … Some key functions  of the membrane involve the import and export of chemical compounds through specialized transmembrane channels, sensory and signaling processes via specialized receptor proteins imbedded in the membrane, and osmotic (water) regulation … through special portals.” 8

“Within the … membrane is the internal cell matrix … called cytosol or cytoplasm, which is a semi-fluid substance.  …  Like the … membrane, the complexity of … cytoplasm seems to grow with every new discovery in cell biology.” 8

Tomkins also tells us that water must be regulated and controlled outside the cell as well in what is called the “extra cellular matrix.” 8

This means that the water of yesteryear, or the distant past, almost certainly performed just like the water of today, and that water, dirt and chemicals, could not have created life anymore than fuel, dirt, and metallic ore, — by themselves — could create a car, motorcycle, or an  airplane: even in millions, billions, or trillions of years.  

For more on why the raw materials on earth cannot produce life, see Life, DNA, and Proteins.9  See also the links below.


*   Although chemists can make DNA in their laboratories, they can only do so under highly controlled conditions that simulate cytosol. They achieve this by using a pre-existing DNA or gene (template), using the right amount of water, magnesium chloride, and salt buffersand by using a pre-existing microscopic / molecular copy machine called DNA polymerase.  Such would not be the case in nature, since genes are not known to form by themselves, nor even simple proteins that consist of only 8 amino acids: much less complex ones that consist of 900–1000 of them, such as DNA polymerase — along with a motor protein called helicase: that actually spins like a motor (at 1800 rpms) and that unwinds the DNA.

**   When two amino acids come together they are called a peptide, and the reaction is called a condensation reaction. (See t the fourasterisks below)  A nucleic acid is a synonym for a nucleotide, and when two or more nucleotides join together they are called an oligonucleotide.

***  According to the American Heritage Dictionary of Science, hydrolysis is “a process of decomposition in which a compound is broken down and changed into other compounds by … (absorbing, or being diluted with) water.  For example, in food digestion, the food absorbs water and is broken down by hydrolysis.  The same dictionary says that tohydrolyze means “to decompose by hydrolysis …”  and that organic molecules such as “Nucleic acids, proteins, and polysaccharides contain many bonds that hydrolyze …  In this regard, the combining word hydro- simply means “of or having to do with water.”

****  Think of a Condensed can of Campbell’s Soup.  The fact that it is “condensed” simply means that water has been removed.

1.   http://opus.bibliothek.uni-wuerzburg.de/volltexte/2003/554/pdf/Thesis-complete-2-library.pdf
2.   Peptide Bond at http://en.wikipedia.org/wiki/peptide_bond.
3.   http://biotech.about.com/od/glossary/g/hydrolysis.htm
4.   
The Creation of Life: a cybernetic approach to evolution, 1970, pp.25-26. Available online through various book sellers. 
5.   Chemistry by Chance: a formula for non-life, Charles McCombs: Acts & Fact, 2/09, pp. 30-31: 
www.icr.org/article/4348/  
6    http://en.wikipedia.org/wiki/Cytosol#Water
7.   Chemistry Refutes Chance Origin of LifePart III, by Jon Covey, B.A., MT, and Anita Millen, M.D., M.P.H.,
       www.creationinthecrossfire.com/Articles/ChemistryRefutes3.html 
8.   The Design and Complexity of the Cell,  Jeffrey Tomkins, Ph. D., 2012, pp. 24-25; http://www.icr.org/design-cell/  
9.   Ref. 7 above by Tomkins, p. 79.
10. Life, DNA, and Proteins: Why raw materials on earth cannot produce life, at http://in6days.tripod.com/id6.html

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