This animation depicts kinesin as similar to a human walking upright on two legs.  Other animations depict motor proteins similar to a human using their arms to swing along monkey bars carrying transport materials with their feet, thus the scientific literature varies on terminology used.  Both interpretations are correct as its just a matter of perspective on which direction is considered up.  

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     Microtubules are an interconnected network of semi-rigid protein structures that maintain the cell’s physical shape and structural integrity, functioning similar to a human skeleton.  A kinesin will pick up materials from location A in the cell, navigate through the microtubule network to location B where the material is needed, unload the material, and then hop on a different microtubule and navigate to its next pickup location.  An analogy is that kinesin behaves like an Uber driver, constantly picking up and transporting passengers from one location to another based on real-time demand for transportation services in different parts of a cell.  

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     Kinesin are assembled from 4 building blocks that are independently produced in different parts of the cell, and come together to form a new kinesin when additional transport capacity is needed to support the demand for transport services.  How this occurs is beyond the scope of this discussion and is another aspect of kinesin behavior that lacks a scientific explanation.  Kinesin are 60 nm (0.000002 inches) in length and their legs are about 1/9 of their height.  Each leg contains about 5,000 atoms held together by electromagnetic bonds with many natural pivot points which function like joints around which its legs and feet can rotate to create smooth walking movements.  Kinesin walk at speeds of up to 100 steps per second so running would be a more appropriate description.  The video above depicts the kinesin walking very slowly in order to illustrate the complex movements of its legs and feet, but in reality it would look more like the road runner in the old Warner Brother's cartoon!   Kinesin take an average of 125 steps when transporting material from point A to point B in a cell, which means they can pick up and deliver up to 24 payloads per minute.  Imagine how much money our kinesin Uber driver would make if they could complete 24 fares every minute! 

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     Multiple kinesin can work join together to transport heavier loads, and they can navigate through tight spaces while avoiding obstacles. Kinesin can push cargo around and reposition themselves with respect to the cargo in order to get a firm grip before transporting the cargo.  When two kinesin approach each other on the same microtubule, one of them will literally step aside and take a different lane of the microtubule (microtubules have 13 lanes) to avoid a collision.  The side stepping occurs when the kinesin are a few nanometers apart but have not made physical contact with one another.  This suggests that kinesin can somehow detect the presence of another kinesin and take evasive action to avoid a collision.  So not only does our kinesin Uber driver know where to pick up and deliver passengers, they also know how to navigate the network of possible roads from point A to point B, and how to take evasive action to avoid collisions en route to its destination.  Before discussing the physics of kinesin movements, we need to discuss the molecule that powers each step, a molecule called ATP.

 

ATP

​​     Adenosine Tri-Phosphate (ATP) is known as the universal energy molecule.  ATP facilitates all chemical reactions inside cells, enables physical movements of subcellular structures, and is the energy source that powers all biological processes.  In multicellular organisms, mitochondria extract electrons from food molecules via the electron transport chain, using the energy released to pump protons (that are also extracted from food molecules) across the inner mitochondrial membrane. The resulting proton concentration gradient drives ATP synthase, a molecular motor embedded in the membrane, to attach a free phosphate group to Adenosine Di-Phosphate (ADP) to form ATP.  The ATP molecule is then sent to various parts of the cell where the electromagnetic energy stored in the bond holding its third phosphate group is released to power biological processes, molecular movements, and chemical reactions throughout the cell.   Every step of this process — from electron transfer in the mitochondria to pumping protons across membranes, to electrostatic phosphate bond breaking, to altering the charge distribution of proteins that ATP interacts with to power the cellular processes of life — is fundamentally driven by the electromagnetic interactions between positively charged protons and negatively charged electrons attracting and repelling each other. 

     After ATP releases its stored electromagnetic energy to drive cellular processes, it is turned back into ADP which travels back to a mitochondrion to be recycled into more ATP.  The typical human cell has roughly 2,000 mitochondria while neurons in the human brain have up to 2 million mitochondria.  Each mitochondria creates approximately 5,000 ATP molecules per second, which means a typical human cell produces and consumes the energy contained in 10 million ATP charge-discharge cycles per second while a typical neuron produces and consumes 10 billion ATP charge-discharge cycles per second.  The ADP-ATP cycle functions like tiny rechargeable electromagnetic batteries that power the processes of life at the sub-cellular scale.

     The phosphate groups released by ATP directly bond with proteins throughout the cell via a process called phosphorylation.  This alters the charge distribution within the protein which in turn alters the protein's physical shape.  This is the process whereby the electromagnetic energy stored in ATP initiates physical movements and/or catalyzes chemical reactions. 

 

     Cells actively maintain a highly negatively charged cell interior using ion pumps in cell membranes.  Biologist Nick Lane uses a striking human scale analogy to illustrate just how negatively charged the cell interior is: 

 

“The voltage across a cell membrane is about 150 millivolts. That doesn’t sound like much, but because the membrane is so thin, the electric field is immense—equivalent to about 30 million volts per meter, similar to a bolt of lightning.”  

     The negatively charged cell interior allows positively charged matter to leverage the electromagnetic force to do work.  What is not widely recognized by the scientific community is that the entirety of biology and chemistry are completely powered by the electromagnetic attraction and repulsion forces between subatomic particles.  The central importance of the electromagnetic force in supporting life cannot be overstated.  Now that we’ve introduced the two molecules involved in transporting materials within cells, it’s time to dive into the physics of ATP and kinesin interactions.

 

Classical Physics and Chemistry Cannot Explain Kinesin Behavior

 

     Researchers have extensively studied kinesin with the goal of explaining their behaviors using physics and chemistry.  While progress has certainly been made, we are still very far from a satisfactory explanation.  The current scientific description for how kinesin can walk goes something like this:

 

• ATP binds to a kinesin leading foot attached to a microtubule, causing molecules in the foot to rearrange their structure, creating a small "docking cleft" on the side of the foot.

• The ATP binding event causes the lower leg to enter the docking cleft, creating tension in the leg which causes it to lean forward.  The forward leaning leg acts as a lever causing the trailing leg to swing forward like a pendulum toward the next binding site on the microtubule.

• One ATP molecule powers one step, thus a sequence of ATP molecules must bind to alternating feet to produce kinesin walking behavior.  This process appears to be precisely coordinated in space and time to ensure that one foot is always anchored to the microtubule, a truly impressive feat given that kinesin can take up to 100 steps per second.  

• As the leading foot grabs onto the microtubule, the trailing foot releases the depleted ATP (now ADP) and closes the docking port in precise synchronization to allow the trailing leg to swing forward.

 

     While this is certainly a reasonably accurate “description” of the physics involved in kinesin leg movement, it lacks a "causal explanation" for what is driving leg movements.  Brownian motion is hypothesized to be the causal influence driving leg movements in one direction, so we will consider this hypothesis.  Brownian motion is the random jittery movement of small particles suspended in a fluid, caused by constant collisions from surrounding fluid molecules that are themselves in continuous thermal motion.  The "Brownian Ratchet" hypothesis as the trigger of kinesin movement along a microtubule goes something like this:

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• Brownian motion creates thermal energy fluctuations in the cellular fluid surrounding the kinesin feet.

• Since Brownian motion is inherently random, the thermal energy fluctuations push against the kinesin feet from all directions.

• ATP hydrolysis creates an asymmetric energy landscape along the microtubule that favors the random thermal fluctuations which push the leg forward versus backwards.

• The result is directed movement that is fundamentally powered by ATP but uses thermal fluctuations as part of the stepping mechanism rather than fighting against them.

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     This hypothesis explains why kinesin always move towards the positive end of microtubules but does not address the causal factors influencing the sequencing and coordination between kinesin and ATP molecules.  For instance, there are no scientific explanations for the following:​

 

• What causal influence guides ATP molecules to precise locations on alternating kinesin feet, with the precise timing to ensure that one foot is always firmly grasping the microtubule, enabling coordinated walking at up to 100 steps per second without falling off?

• What causal influence initiates the first kinesin step, timing the first ATP molecule to interact with a foot once a new payload has been successfully loaded and is held securely before initiating the first step?  In other words, where is the feedback mechanism that triggers walking movements only after a payload is ready to be transported?

• What causes the stream of ATP molecules to stop interacting with the feet once the kinesin reaches it destination?

• How do kinesin know where materials need to be picked and where they need to be delivered?

• How does kinesin know which path to take through the vast microtubule network to transport cargo to the target location in the cell that needs the material?

• How does kinesin detect the presence of other kinesin and know how to take evasive action by stepping sideways onto another lane of the microtubule to avoid a collision?  What causes ATP molecules to stop powering feet movements in one direction and reorient its angle of engagement with a foot to initiate a sideways step that seemingly violates the Brownian motion hypothesis?

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     There are more unanswerable questions regarding the causal influences behind kinesin behaviors, but hopefully you get the point.  The behaviors of kinesin and ATP require some type of causal signal to trigger and control the behaviors discussed, implying the existence of a control system that actively monitors kinesin and ATP locations and activities in order to precisely coordinate the timing and navigation instructions via a stream of signals to guide ATP and kinesin movements.  No such signals or control system have been found to date, but that doesn’t stop us from speculating on what the nature of this control system.  Reductionist scientific logic suggests that whatever is controlling ATP and kinesin must be a mechanical, chemical, electromagnetic, and/or quantum process.  Let’s consider each possibility.

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     Mechanical processes may be able to explain the sequential steps using the laws of inertia and momentum which could cause alternating legs to move forward as described above, but these descriptions cannot explain the causal mechanism triggering a kinesin to take an initial step, so let’s focus on what process might initiate a first step.  No mechanical structures nor chemical signals have been found that surround and guide ATP molecules as they move toward a Kinesin foot to initiate a first step, so we can easily rule them out.  An electromagnetic process would require the generation and manipulation of tiny electromagnetic fields that vary in their orientation in 3-dimensional space with 3nm (0.0000001 inch) precision to effectively guide ATP molecules to a specific location on a kinesin foot.  These nanoscale electromagnetic fields would also have to guide a stream of ATP molecules to alternating feet with incredible precision.  These fields could be generated from within the microtubules to attract ATP molecules to the kinesin feet since kinesin always travel towards the positive end of microtubules while their sister motor proteins called dynein always travel towards the negative end?  Perhaps, but the fields that attract ATP would need to be initiated only after the kinesin or dynein has secured its payload, which raises the question of how this signal is generated and received?  The propagating electromagnetic field traveling within a microtubule would also have to travel through a network of microtubules from point A to point B, transferring to different microtubules along the way.  It simply strains credulity to assume that the tens of thousands of motor proteins simultaneously carrying payloads around the cell can be precisely controlled and coordinated by nanoscale electromagnetic fields propagating through microtubule networks without some type of cell-wide system guiding these fields.  And remember, we are only talking about motor proteins while ignoring the trillions of other chemical reactions and molecular movements that are occurring simultaneously inside each cell, all of which are precisely coordinated to keep the cell alive.

     It seems likely that whatever is generating these electromagnetic fields which drive ATP and kinesin interactions would be generated locally in the vicinity of the kinesin given the nanoscale precision of the movements being controlled.  But no atoms or molecules have been found emitting photons to generate these fields and guide the movements.  It is scientifically naive to assume that electromagnetic waves traveling inside microtubules can (a) attract ATP and kinesin feet to bond with the microtubule, (b) with precise timing to initiate the first step once a payload is loaded, (c) synchronize alternating high speed steps along a series of paths through the microtubule network, (d) identifying potential collisions and orchestrate evasive action by causing one kinesin to step aside to let another pass, (e) cease all movement when the kinesin reaches its destination, and (f) initiate the unloading of payloads at the destination where the payload is needed.  The only logical conclusion to draw is that the kinesin and/or ATP must be controlling these movements, a possibility that would require them to have some form of cognition and agency, attributes that we normally associate with having a mind.

     In addition to moving material around the cell, kinesin also play a vital role in cell division, assembling spindles, aligning chromosomes at the metaphase plate, pushing spindle poles apart, elongating microtubules, ensuring proper separation of genetic material, and much more.  Walking is the simplest behavior these workhorse molecules demonstrate.  We have been unable to explain the behaviors of motor protein using classical physics and chemistry, and since electromagnetic fields are quantum phenomena, let’s explore whether the source of our missing control system could be quantum in nature.

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Quantum Physics Cannot Explain Kinesin Behavior

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     The properties and behaviors of atoms and molecules are described by quantum physics, the branch of science that models the behavior of the smallest known bits of matter and energy in the universe.  Quantum theory and quantum mechanics are a set of rules and analytical tools to predict the “range of possible properties” of a quantum system when it is measured or observed.  It cannot predict the outcome of any single measurement with any precision whatsoever as it is limited to predicting the statistical distribution of possible outcomes across a series of experiments. The 1st key takeaway is that quantum theory is fundamentally indeterminate.

     A foundational assumption in quantum theory is that the behavior of quantum scale matter is “random” in nature.  While the statistical predictions of quantum theory are extraordinarily well verified experimentally, the assumption that underlying individual quantum events are driven by fundamentally random processes remains a philosophical interpretation rather than a directly proven fact — an interpretation challenged by deterministic alternatives such as pilot wave theory.  What has been empirically deduced is that when performing a large number of experiments, such as sending a beam of electrons or photons through a double slit apparatus, the particles will over time produce a statistical distribution of impacts on a detector screen, resulting in an interference pattern that illustrates the wave-like nature of matter and energy.  Because a predictable distribution of photon impacts on the screen results over time, quantum physicists "assume" the location where any given photon hits the screen is driven by a statistically random process.  While this does not prove the underlying causal influence guiding the photons is random, it is certainly consistent with the "hypothesis" that the underlying driver of quantum behavior "may" be statistically random.  The 2nd key takeaway is that quantum indeterminacy is assumed to be driven by random processes in mainstream science.

     If the indeterminate behavior of quantum scale matter is truly driven by random processes as posited in mainstream quantum theory, then the theory can offer no explanation for the control of ATP and Kinesin that we are searching for.  The same argument exists for the Brownian motion hypothesis discussed earlier, whereby random thermal processes can offer no explanation for the control of kinesin and ATP that we are searching for.  It is simply unscientific to assume that random quantum processes or random thermal fluctuations can cause the precise timing and coordination of thousands of kinesin walking on microtubules within each cell, run at speeds of up to 100 steps per second, cause kinesin to pick up materials at point A, navigate the vast network of microtubules to deliver cargo to point B where it happens to be needed, and to detect the presence of other kinesin and change lanes to avoid a collision.  And kinesin are just one type of molecule inside cells, which contain trillions of molecules executing millions of complex and highly coordinated chemical and electromagnetic reactions every second inside each of the 30 trillion cells in your body to keep each cell, and you, alive.

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Conclusion

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     The behavior of molecules inside cells provide clear evidence of goal directedness at the molecular scale which simply cannot be explained as the result of countless quadrillions of random quantum processes.  Something fundamental is missing from modern science in order to explain the behaviors of the billions of molecules inside cells that collectively orchestrate the symphony of life.  We view the complex, intelligent behavior of kinesin motor proteins as evidence of cognition and agency at the molecular scale, skills that cannot be explained with existing scientific theories.  There is a rapidly growing body of evidence similar to kinesin in many other molecules operating inside cells including DNA, RNA, mTor, Intrinsically Disordered Proteins (IDPs), phase separated droplets, and viruses to name a few.  Each of these molecular structures will be discussed in upcoming molecular mind blog posts, which collectively provide compelling evidence that mind exists at the molecular scale.  The subcellular world can best be understood as a society of molecular scale minds collaborating to keep their cellular ecosystem alive.  This hypothesis requires explaining how molecules with minds can control their molecular scale bodies by pushing the boundaries of existing physics, chemistry, and thermodynamics.  This will be discussed in more detail in the next section title Mind-Matter Interaction.