Note the animation depicts the kinesin as similar to a human walking upright on two legs while the earlier video depicts dynein as using two arms like a human swinging from monkey bars.  Both are correct as its just a matter of perspective of which direction is considered up.  We will focus our discussion on the simpler motor protein kinesin and refer to kinesin as walking along microtubules because the latter video is the one that went viral and thus is more well known.​​

​

     Microtubules are an interconnected network of semi-rigid protein structures that maintain the cell’s physical shape and structural integrity, performing a similar function as the human skeleton.  A kinesin will pick up materials from one location in the cell, navigate through the microtubule network to the location the material is needed, unload the material, and then hop on a different microtubule to navigate to its next pickup location.  A useful analogy we will use 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.  

​

     Kinesin are protein complexes assembled from 4 building blocks that are independently produced in different parts of the cell, and which 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.  For clarity purposes, we will use words for kinesin body parts (arms, legs, and feet) which intuitively map to the video above, rather than use their scientific terms which map to the research literature.  The arms hold the cargo, the legs move to create the walking motion, and the feet grab on to microtubules. 

​

     Kinesin are 60 nm (or 0.000002 inches) in length and have two “legs” that make up about 1/9 of their height.  Each leg contains about 5,000 atoms held together by electromagnetic bonds with many natural pivot points which can function like “joints” around which its legs and feet can rotate to create smooth walking movements.  Kinesin can walk at speeds of up to 100 steps per second and take an average of 125 steps when transporting material from point A to point B inside a cell.  This means that Kinesin 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!  The video above shows a kinesin walking very slowly, but kinesin actually runs very fast along microtubules, reminding me of the road runner cartoons I loved as a child.

 

     Multiple kinesin can join together to navigate complex 3D scaffolds and avoid obstacles. Kinesin are able to loosely hold cargo and slide along the surface of the cargo to get a better grip on its cargo.  This allows kinesin to reorient itself while carrying cargo in tight quarters to avoid obstacles.  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 (there are 13 lanes on a microtubule) to avoid a collision.  The side stepping occurs when the kinesin are a few nanometers from each other but not yet making physical contact.  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, it also knows 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 analyzing the physics of kinesin walking motions, its important to discuss the molecule that powers each step, a molecule called ATP.

 

ATP

​​

     Adenosine Tri-Phosphate (ATP) is known as the universal energy molecule.  It facilitates all chemical reactions inside cells, enables all physical movements of subcellular structures, and is the sole energy source that powers all biological processes.  In multicellular organisms, the mitochondria strip four protons off passing food or oxygen molecules which are then attached as a 3rd phosphate molecule to Adenosine Di-Phosphate (ADP) to form ATP.  The ATP is then sent to various parts of the cell where it releases its 3rd phosphate and a proton to power biological processes.  When ATP releases its charged particles, it is turned back into ADP, which travels to a mitochondria to be recycled into more ATP.  The ADP-ATP cycle functions like tiny rechargeable batteries that power all of life’s processes.

​

     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.  Meanwhile a typical neuron produces and consumes the energy contained in 10 billion ATP charge-discharge cycles per second, consuming a mind-boggling amount of energy to process information and generate synapses in addition to executing processes to keep the neuron alive. 

 

     The phosphate molecule released by ATP binds to proteins, altering a protein’s shape and initiating a variety of physical movements.  The physical movements of molecules powered by ATP inside cells is what generates the heat that keeps the human body at 98.6 degrees F (37 degrees C).  We won’t get into body-wide homeostatic processes like thermal management, but they are incredibly fascinating processes that also evade scientific explanation.  Finally the 4th proton released by ATP is attracted by negatively charged molecules in the cell and used to catalyze a wide range of chemical reactions.  

Cells actively maintain a negatively charged interior using ion pumps in the cell membrane.  Biologist Nick Lane provides a useful human scale analogy to illustrate just how negatively charged a 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 highly negatively charged cell interior is basically starved of positively charged protons, which allows any positively charged matter to leverage the electromagnetic force to do work.  Every biological process, just like every chemical process, is entirely driven by the electromagnetic attraction between electrons and protons being exchanged and/or shared between atoms.  Now that we’ve introduced the two molecules involved in transporting materials within cells, it’s time to dive into the physics.

 

Classical Physics Cannot Explain Walking Kinesin

 

     Researchers have extensively studied kinesin with the goal of explaining their behaviors using existing 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:

​

1. ATP binds to the kinesin’s 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.

2. The ATP binding event causes the lower leg to enter the docking cleft, creating tension in the leg that 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.

3. To ensure the kinesin moves forward without falling off the microtubule as it walks, a steady stream of ATP molecules arrives at the kinesin feet in an alternating pattern, where one ATP molecule powers one step, and must be precisely timed such that one foot is always securely anchored to the microtubule. 

4. Once the leading foot grabs onto the microtubule, the trailing foot releases its ATP and closes the docking port in precise synchronization to allow the trailing leg to swing forward.

 

     While this is certainly an accurate description of the physical mechanics of kinesin walking, there are many aspects of these movements that are not understood, including:

​

• How are the series of ATP molecules guided to precise locations to bind to alternating feet, precisely timed to ensure one foot is always firmly grasping the microtubule, enabling coordinated walking at up to 100 steps per second?

• How do kinesin feet know that a new payload has been loaded and is securely held before it initiates its first step?

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

• How do 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 the feet moving in one direction and reorient its angle of engagement with a foot to suddenly initiate a sideways step?

 

     We could go on raising more unanswerable questions, but hopefully you get the point.  Each of these actions presumably requires some type of causal signal to trigger and control the behavior, implying the existence of some type of control system which is monitoring kinesin activity and precisely coordinating the timing and content of a stream of sequential signals to guide kinesin movements.  No such signals nor control system have been found to-date, but that doesn’t stop us from speculating on what it could be.  Whatever is controlling the ATP and kinesin must involve either a mechanical, chemical, electromagnetic, and/or quantum process.  Let’s consider each possibility. 

 

     Mechanical processes might be able to explain a sequence of steps using the laws of inertia and momentum causing alternating legs to move forward as described above, but these descriptions cannot explain a kinesin taking an initial step, so let’s focus on taking a first.  No mechanical structures nor chemical signals have been found surrounding and guiding ATP molecules as they move to a Kinesin foot to initiate a first step, so we can rule them out.  An electromagnetic process would require the generation and manipulation of tiny electromagnetic fields that vary their orientation in 3 dimensional space with 3nm (0.0000001 inch) precision to effectively guide ATP molecules to a specific location on a foot, followed by tiny electromagnetic fields that guide ATP molecules to alternating feet.  These fields would have to be generated by photon emissions somewhere inside the cell, and it simply strains credulity to assume that a cell-wide electromagnetic control system exists that could operate with this level of precision at the feet of tens of thousands of kinesin simultaneously carrying payloads around the cell.  And remember, we are only talking about the simplest movement of the simplest motor protein, while ignoring the millions of other chemical reactions and movements that are occurring every second inside cells that are densely packed with organelles and molecules all performing their duties to keep the cell alive.  

​

     It seems far more likely that our hypothetical electromagnetic control system would be generated locally in the vicinity of the kinesin, rather than from a centralized location in the cell.  But no atoms nor molecules have been found emitting photons to guide ATP in the vicinity of the kinesin feet.  It is also beyond reasonable to assume that electromagnetic waves are traveling inside microtubules that (a) attract ATP and kinesin feet to bond with the microtubule, (b) with precise and highly synchronized timing to initiate the first step once a payload of loaded, (c) alternate high speed steps along a series of paths through the microtubule network, (d) coordinate one kinesin stepping aside to let another pass, (e) stop walking when the kinesin reaches its destination, and (f) initiate the unloading of its payload.  The only logical conclusion to draw is that the kinesin and/or ATP must be self-generating the electromagnetic fields necessary to guide their movements.  But this would mean that kinesin and ATP control their own 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 plays 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 that kinesin demonstrate.  We have been unable to explain the simplest behavior of the simplest motor protein, which logically should be one of the easier behaviors to explain scientifically.  Classical physics appears to come up short, and since photons and electromagnetic fields are quantum phenomena, let’s explore whether the source of our missing control system could be quantum in nature.

​

Quantum Theory

​

     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.  This assumption of randomness is just that, an assumption, one that has not been empirically proven to be valid.  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" that this means where each photon hits the scene is driven by a statistically random process.  While this does not "prove" the underlying causal influence guiding the photons is random, it does support 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.

​

     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 any explanation for the control of ATP and Kinesin that we are searching for.  It is simply unscientific to assume that random quantum processes can produce 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 only one type of molecules inside cells, which contain of billons of molecules executing millions of complex and coordinated chemical and electromagnetic reactions every second inside each of the 30 trillion cells in your body to keep each cell, and you, alive.  

​

Conclusion

​

     Something fundamental is missing from modern science in order to explain the seemingly intelligent behaviors of billions of molecules that collectively orchestrate the symphony of life inside each cell. The complex, seemingly intelligent behavior of kinesin motor proteins cannot be explained with existing scientific theories, hence these walking molecules can best be understood as having molecular scale minds that control their molecular scale bodies.  A discussion on how they may be able to do this is in the subsequent theory section that discusses mind-matter interactions.  We have found a growing body of evidence similar to kinesin in many other molecules inside cells including DNA, RNA, mTor, Intrinsically Disordered Proteins (IDPs), phase separated droplets, and viruses.  Each of these molecular structures will be discussed in upcoming molecular mind blog posts, all of which provide compelling evidence that mind exists at the molecular scale.