LUCA, Beginning of Life, and the Origin and Complexity of a Living Cell
The cell is a fantastically complicated system. It is the heart of all living things. It seems the more we study it the more complicated and elusive its understanding becomes. What seems to drive its functionality? Has science been able to duplicate it? These important questions will be discussed in this article.
The Science
The shift in our understanding of the cell is one of the most dramatic "zoom-ins" in scientific history. In 150 years, we have gone from viewing the cell as a simple blob of jelly to seeing it as a hyper-complex automated city governed by digital code.
In the late 19th century, the best microscopes showed the cell as a membrane filled with a mysterious, translucent substance called protoplasm. Scientists like Thomas Henry Huxley described the cell as the "physical basis of life," but they believed it was a relatively simple, homogeneous fluid. The nucleus was known, and "granules" were visible, but their functions were a total mystery. It was essentially a "black box"—we knew life happened inside, but we didn't know how. Hope was high that if these substances could be duplicated and then energized (say with lighting) that life could be produced in a test tube.
As staining techniques and microscope lenses improved in the early 1900’s, the "blob" began to reveal distinct structures. We discovered the Mitochondria (1890s) and the Golgi Apparatus (1898). The cell was no longer a single fluid; it was a collection of specialized "organs" (organelles). The cell was viewed as a factory. It had a power plant (mitochondria), a shipping center (Golgi), and a control center (nucleus).
The discovery of the Double Helix structure of DNA in 1953 changed everything. We realized the cell wasn't just a chemical factory; it was a computer. The nucleus wasn't just a "boss"—it was a hard drive containing a four-letter digital code ($A, T, C, G$). We began to understand Protein Synthesis. The cell was transcribing data (mRNA) and translating it into 3D machinery (proteins) with incredible precision.
Today, thanks to electron microscopy and fluorescent tagging, we see the cell as a masterpiece of nanotechnology. We now know the cell is filled with literal motors, like Kinesin, which "walks" along microtubule tracks to deliver cargo. This is where the debate often sparks. The "simplest" self-replicating cell requires hundreds of specific proteins, a sophisticated membrane, and a coding system all working simultaneously. The cell is a high-speed automated city. It features:
Error-correction: DNA polymerases that "proofread" code for typos.
Automated Waste Management: Lysosomes and proteasomes that recycle old parts.
Smart Gates: Ion channels that decide which atoms can enter or leave.
A kinesin motor protein complex found in eukaryotic cells moving along microtubule (MT) filaments. It can walk up to 800 nm/s. 2
Perhaps the best example of modern complexity is ATP Synthase. It is a literal rotary engine that spins at speeds up to 9,000 RPM to produce the cell's energy currency. It consists of two main parts: the $F_0$ portion (the rotor) embedded in the membrane and the $F_1$ portion (the stator) that protrudes from it. As protons flow through the $F_0$ rotor, it spins. This mechanical rotation changes the shape of the $F_1$ units, which "crush" ADP and phosphate together to create ATP, the universal energy currency of life.
150 years ago, we didn't even know where energy came from; now, we can see the "gears" of the engine that creates it.
The whole ATP synthase machine with individually manufactured protein subunits each labelled with Greek letters. H⁺ ions (protons) flow through a special tunnel in ATP synthase, as the arrow indicates. This induces mechanical motion, forcing the axle and base to spin together like a turbine. Nearly 100% of the spinning momentum is converted to chemical energy in the formation of ATP molecules! Three ATPs are produced for every 10 protons. 2
So let’s discuss creating life. A living cell is often described as the smallest unit of life. While cells vary wildly in shape and function—from the long, branching neurons in your brain to the simple, rod-shaped bacteria in a drop of water—all living cells share a core set of characteristics that allow them to function as independent, biological machines. To be considered a "living cell," an entity must generally possess the following attributes:
The Boundary (Cell Membrane) - Every cell is encased in a plasma membrane. This is not just a "bag"; it is a sophisticated, semi-permeable "smart gate" made of a phospholipid bilayer. It maintains “homeostasis” by controlling exactly which molecules (like glucose or ions) enter and which waste products exit.
Genetic Material (The Instructions) - All living cells contain DNA (Deoxyribonucleic acid) as their hereditary material. DNA acts as the biological "blueprints" or digital code required for the cell to build proteins and replicate itself. In complex cells (eukaryotes), this is housed in a nucleus; in simpler cells (prokaryotes), it floats in a region called the nucleoid.
Metabolism (Energy Utilization) - A cell must be able to take in nutrients and convert them into energy to perform work. This usually involves chemical reactions like cellular respiration or photosynthesis. Most cells convert energy into ATP (Adenosine Triphosphate), which powers the molecular motors and chemical pumps inside the cell.
Protein Synthesis (The Machinery) - Living cells contain ribosomes, which are the "construction workers" of the cell. Ribosomes read the instructions from the DNA (via an intermediate called mRNA) and physically assemble chains of amino acids into proteins. Proteins do almost all the heavy lifting, from structural support to acting as enzymes that speed up chemical reactions.
Growth and Development - A living cell does not remain static. It increases in size by accumulating organic molecules and can change its internal structure to adapt to its environment.
Reproduction (The Ability to Multiply) - One of the most defining characteristics of life is the ability to produce offspring. Cells replicate their DNA and then divide through processes like binary fission (in bacteria) or mitosis (in human body cells). This ensures that life continues from one generation to the next.
Response to Stimuli - Cells are "aware" of their surroundings. They can detect changes in temperature, light, or the presence of chemicals and move toward or away from them (chemotaxis).
So how did the LUCA (Last Universal Common Ancestor) come into being? To show that life somehow just happened from the “primortal ooze” and obtained these 7 attributes we must be able to do two things: 1) spontaneously create the molecules contained in the living cell, and, 2) give the cell the “spark of anonymity”. Molecules don’t care about life. They have no desires. Somehow we need to identify that spark and spontaneously create it.
Dr. James Tour, an American synthetic biochemist and co-author of “The Mystery of Life’s Origin” 3, has identified four fundamental molecules which are the building blocks of life. These are: Polysaccharides (Monomeric Sugars), Polypeptides (made from Amino Acids), Polynucleotides, and Lipids. Nobody has shown a method to make the enantiopure versions of carbohydrates, amino acids, nucleotides, or lipids in a prebiotically relevant manner.
Molecules of living systems. Red arrows show Steriogenic sensors or cairocenters. 4
He goes on to say that “nobody has solved the polymer stability problem when dealing with single molecules. Time is the enemy of life. This is contrary to the leading argument of evolutionists who say that chances of spontaneous life increase with time. Everything falls apart with time, or has a chemical entropy. For instance a 600-mer sample of identical RNAs have a half-life of about 100 days (2400 hours) in water at room temperature, then for a single RNA molecule you have a lifetime of 4 hours (2400 hours / 600). Even a single 200-mer polypeptide in water has a lifetime of about 13 days.”
“Nobody has explained how the requisite protein folding could have occurred. Even a single protein could not arrive at its native structure in biological real-time by random search because conformational space is far too vast (1095 possible conformations).”
“Nobody has solved the code problem for ordering the nucleotides (or saccharides or proteins if those came first).
“Nobody has been able to resurrect a cell, or make a dead cell come back to life. We can’t even describe what was lost when a cell dies.”
Perhaps someday science will be able to spontaneously generate these molecules and the spark of life that gives it animation. However, now it seems that as we study the living cell, it becomes more complex and further away from our grasp.
The Religion (see Hello World, I’m Alive!)
The bible simply says that God breathed into [Adam’s] nostrils the breath of life; and man became a living soul. (Gen 2:7). The scriptures also state that Jesus Christ is the light and life of man:
John 1:4: "In him was life; and the life was the light of men."
John 8:12: "Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life."
John 11:25: "Jesus said unto her, I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live."
John 14:6: "Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me."
1 John 1:1-2: "That which was from the beginning... of the Word of life; (For the life was manifested, and we have seen it, and bear witness, and shew unto you that eternal life...)"
1 John 5:12: "He that hath the Son hath life; and he that hath not the Son of God hath not life."
2 Timothy 1:10: "...but is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel."
Ephesians 5:14: "Wherefore he saith, Awake thou that sleepest, and arise from the dead, and Christ shall give thee light."
This seems to state that Jesus Christ has two roles being mentioned. One, he is the light; truth, way to happiness, key to salvation, etc. (I think that this is more than electromagnetic radiation.) Another, He gives us quickening, animation, salvation from the grave. He is the vine that gives us life. I don’t think that this imagery is just a metaphor. This isn’t just talking about spirits going back into our bodies, but both our spirits and physical bodies receiving animation from the Savior. He is the resurrection and the life.
The Summary
It seems that our understanding of the cell is like peeling an onion. Once we remove a layer we discover a whole new layer underneath. As scientists try to understand the cell, and even create life, the goal posts keep being moved further out. As a scientist I will never say that we will never get there, but over the past 150 years it seems that the dream of showing how life evolved has become more elusive.
https://www.youtube.com/watch?v=y-uuk4Pr2i8&t=21s
Adapted from Kanehisa Laboratories, www.genome.jp/kegg.
https://www.discovery.org/m/securepdfs/2021/02/Tour-MeyerMOLO.pdf
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