A robotic assembly line finds its equivalent in the biological world through biosynthesis and metabolic pathways (also called biogenesis or anabolism) which is a multi-step, enzyme-catalyzed ( robots ) process where substrates ( unfinished parts ) are converted into more complex products. In biosynthesis, simple compounds are modified, converted into other compounds, or joined together to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Also the biosynthesis of heme happens in mitochondria and cytosol. 1)
Metabolic activity makes it possible for organisms to extract energy from the environment and make life’s component parts. These processes allow organisms to grow, reproduce, maintain biological structures, and respond to changes in the environment. Metabolic processes within the cell’s interior are organized into pathways consisting of a series of chemical reactions that transform a starting compound into a final product via a series of small, stepwise chemical changes. Each step in a metabolic route is mediated by a protein (called an enzyme) that assists in the chemical transformation.
Metabolic pathways can be linear, branched, or circular. The chemical components that are part of a particular metabolic sequence sometimes take part in other metabolic pathways. These shared compounds cause metabolic pathways to be networked together.3)
Metabolism involves reactions of small molecules. A significant number of metabolic reactions produce small molecules used by the cell’s machinery as building blocks to assemble proteins, DNA, the RNAs and cell membrane bilayers. On the other hand, some metabolic activities breakdown compounds like glucose and other sugar molecules into smaller molecules to provide energy for the cell’s operations. Some metabolic activities prepare materials the cell no longer needs (cellular waste) for elimination. Other reactions detoxify materials harmful to the cell. 4)
METABOLISM - all biochemical reactions that transform matter, energy and information
3 basic stages:
1. Uptake of substances (for example, across the plasma membrane)
2. Transformation of substances (anabolism or catabolism - explained a bit later!)
3. Release of substances (for example, the elimination of metabolic wastes across the plasma membrane) 2)
Metabolic pathway- the order in which reactions affecting a starting substance occur. A metabolic pathway may be linear or circular and the product (end substance) of one pathway may be the reactant (starting substance) of another. Often reactions in a pathway are reversible.
All pathways have the following participants:
1. Substrates/reactants - substances that enter the reaction
2. Intermediate products - compounds formed between the start and the end of the reaction
3. Enzymes - proteins that catalyze (speed up) reactions
4. Energy carriers - usually ATP. It donates energy to the reactions that need it and picks up energy from reactions that produce it.
5. End products /metabolites - substances produced at the end of the pathway.
Metabolic pathways in general are found to be ‘optimal’:
Metabolism: A Cascade of Design
Excerpt: A team of biological and chemical engineers wanted to understand just how robust metabolic pathways are. To gain this insight, the researchers compared how far the errors cascade in pathways found in a variety of single-celled organisms with errors in randomly generated metabolic pathways. They learned that when defects occur in the cell’s metabolic pathways, they cascade much shorter distances than when errors occur in random metabolic routes. Thus, it appears that metabolic pathways in nature are highly optimized and unusually robust, demonstrating that metabolic networks in the protoplasm are not haphazardly arranged but highly organized. 3)
Highly optimized, unusually robust, highly organized are atributes that i would rather ascribe to be the product of a intelligent agency, than random evolutionary forces.
Given the dynamic environment of the cell, fluctuations in the levels of metabolites are bound to happen. When these unintended variations occur, they will travel throughout the networks. Some processes in the cell are sensitive to metabolite concentrations and will be negatively affected as a result. To combat these affects, metabolic systems have regulatory systems in place (based on engineering principles) that dampen concentration bounces, keeping them within tight bounds. In other words, metabolic pathways are optimized to withstand inevitable concentration changes of metabolites.
The paralleles to above factory example is clear. The optimization of the factory assembly line is a important design requirement ( maximal flexibility in the line for demand and supply fluctuation ) and are best explained and achieved through the rational planning and design of intelligent minds.
The salient characteristics of biochemical systems, such as their optimization, are identical to features we would immediately recognize as evidence for the work of a human designer. The similarities between biochemical systems and manmade machines logically compels the conclusion that life’s most fundamental processes and structures stem from the work of an intelligent Agent. 4)
So what are the best answers that our friends, proponents of natural mechanisms have on hand ?
Origin and evolution of metabolic pathways
How the major metabolic pathways actually originated is still an open question nice admittance !! but several different theories have been suggested to account for the establishment of metabolic routes, as The Retrograde hypothesis (Horowitz, 1945), The Granick hypothesis, The Patchwork hypothesis (Ycas, 1974; Jensen, 1976), Semienzymatic origin of metabolic pathways (Lazcano and Miller,1996), The bioinformatic approach , The directed evolution experiments All these ideas are based on gene duplication. 7)
Is gene duplication a viable explanation for the origination of biological information and complexity?
Although the process of gene duplication and subsequent random mutation has certainly contributed to the size and diversity of the genome, it is alone insufficient in explaining the origination of the highly complex information pertinent to the essential functioning of living organisms. 8
If a certain line of reasoning is not persuasive or convincing, then why do atheists not change their mind because of it? The more evolution papers are published, the less likely the scenario of gene duplication ( even questioned by peer reviewed papers, as shown above ) , mutation, and natural selection becomes. We should consider the fact that modern biology scientific research may have reached its limits on several key subjects, to which biosynthesis pathways belong. All discussions on principal theories and experiments in the field either end in vague suppositions and guesswork, statements of blind faith, made up scenarios, or in a confession of ignorance. Fact is there remains a huge gulf in our understanding. This lack of understanding is not just ignorance about some technical details; it is a big conceptual gap. The reach of the end of the road is evident in regard of many, if not almost all major questions. The big questions of macro evolutionary changes and abiogenesis are very far from being clearly formulated, even understood, and nowhere near being solved, and for most, there is no solution at all at sight. But proponents of evolution firmly believe, one day a solution will be found. Not only that, but it seems, the ones that less understand the subject, the more they believe to have the right answers and philosophical position, almost like religious fundamentalists. Istn't that a prima facie of a " evolution of the gap" position ? We don't know yet, but evolution and naturalism must be true anyway ? So, the God hypothesis remains out of the equation as a real possibility in the beginning, and so at the end, and never receives a serious and honest consideration. If the scientific evidence does not lead towards naturalism providing sactisfactory explanations, why should we not change your minds and look somewhere else ?