Your Body's Molecular Machines

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Veritasium

3 år sedan

These are the molecular machines inside your body that make cell division possible. Animation by Drew Berry at the Walter and Eliza Hall Institute of Medical Research. wehi.tv
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Every day in an adult human roughly 50-70 billion of your cells die. They may be damaged, stressed, or just plain old - this is normal, in fact it’s called programmed cell death.
To make up for that loss, right now, inside your body, billions of cells are dividing, creating new cells.
And cell division, also called mitosis, requires an army of tiny molecular machines.DNA is a good place to start - the double helix molecule that we always talk about.
This is a scientifically accurate depiction of DNA. If you unwind the two strands you can see that each has a sugar phosphate backbone connected to the sequence of nucleic acid base pairs, known by the letters A,T,G, and C.
Now the strands run in opposite directions, which is important when you go to copy DNA. Copying DNA is one of the first steps in cell division. Here the two strands of DNA are being unwound and separated by the tiny blue molecular machine called helicase.
It literally spins as fast as a jet engine! The strand of DNA on the right has its complimentary strand assembled continuously but the other strand is more complicated because it runs in the opposite direction.
So it must be looped out with its compliment strand assembled in reverse, section by section. At the end of this process you have two identical DNA molecules, each one a few centimeters long but just a couple nanometers wide.
To prevent the DNA from becoming a tangled mess, it is wrapped around proteins called a histones, forming a nucleosome.
These nucleosomes are bundled together into a fiber known as chromatin, which is further looped and coiled to form a chromosome, one of the largest molecular structures in your body.
You can actually see chromosomes under a microscope in dividing cells - only then do they take on their characteristic shape.
The process of dividing the cell takes around an hour in mammals. This footage is from a time lapse. You can see how the chromosomes line up on the equator of the cell. When everything is right they are pulled apart into the two new daughter cells, each one containing an identical copy of DNA.
As simple as it looks, this process is incredibly complicated and requires even more fascinating molecular machines to accomplish it. Let’s look at a single chromosome. One chromosome consists of two sausage-shaped chromatids - containing the identical copies of DNA made earlier. Each chromatid is attached to microtubule fibers, which guide and help align them in the correct position. The microtubules are connected to the chromatid at the kinetochore, here colored red.
The kinetochore consists of hundreds of proteins working together to achieve multiple objectives - it’s one of the most sophisticated molecular mechanisms inside your body. The kinetochore is central to the successful separation of the chromatids. It creates a dynamic connection between the chromosome and the microtubules. For a reason no one’s yet been able to figure out, the microtubules are constantly being built at one end and deconstructed at the other.
While the chromosome is still getting ready, the kinetochore sends out a chemical stop signal to the rest of the cell, shown here by the red molecules, basically saying this chromosome is not yet ready to divide
The kinetochore also mechanically senses tension. When the tension is just right and the position and attachment are correct all the proteins get ready, shown here by turning green.
At this point the stop signal broadcasting system is not switched off. Instead it is literally carried away from the kinetochore down the microtubules by a dynein motor. This is really what it looks like. It has long ‘legs’ so it can avoid obstacles and step over the kinesins, molecular motors walking the other direction.
Studio filming by Raquel Nuno

Kommentarer
ace10229
ace10229 4 dagar sedan
Try watching this while tripping.
Jamal Ayesh
Jamal Ayesh 10 dagar sedan
The human being and every single organelle, cell, tissue... in it is the most amazing and most complex machine in the universe; however technology gets advanced, it'll never come to develop anything near the complexity and functionality of a single organelle 🤯. So how about that this a single organelle in a cell of trillions of cells of one complete human being of billions of humans, never forgetting the enormous number of other miscellaneous species in the universe. "God is the Creator of all things, and He is the Maintainer of everything." GLORY BE TO ALL-MIGHTY GOD.
ExtantFrodo2
ExtantFrodo2 10 dagar sedan
So because you don't understand that you evolved, you make believe a being exists that could construct us by breathing on a statue. Do you also believe in Hogwarts?
Tom Holland
Tom Holland 11 dagar sedan
Design at its finest!
ExtantFrodo2
ExtantFrodo2 10 dagar sedan
Normal evolution. A designer would not be as limited.
LAGoff
LAGoff 13 dagar sedan
And then to add several more layers to the complexity, doesn't each molecule need to be escorted to its place? And doesn't that escort molecule need to be escorted?
ExtantFrodo2
ExtantFrodo2 7 dagar sedan
@LAGoff I forget it's name. It's an iron metabolizing bacterial species.
LAGoff
LAGoff 8 dagar sedan
@ExtantFrodo2 I'd like a name for this cell or a site I can study it more. This would mean that Brownian motion is all that is technically needed for life. Since the first life is what I am really most interested in perhaps I should start with your Brownian cell.
ExtantFrodo2
ExtantFrodo2 8 dagar sedan
@LAGoff *" I was told most of the processes in the cell are happening under catalysis (active transport), not randomness. (Brownian motion)"* This is true (as I said). But there exist cells deep underground which are not so highly evolved that take tens of thousands of years to replicate because they do not yet have catalytic enhancers for everything. *"What do you mean by 'walk'? "* tumble - sorry, I forgot how literal you need to be. No more analogies for you.
LAGoff
LAGoff 9 dagar sedan
@ExtantFrodo2 What do you mean by 'walk'? tRNA doesn't walk to the ribosome. I was told most of the processes in the cell are happening under catalysis (active transport), not randomness. (Brownian motion) The only walking I know of in the cell is that goofy critter that walks along the track/spindle impelled by mol pol. The tRNA (and its cargo) I watched in the animation does not move on a track/spindle. Are you saying the tRNA is just thrown out into the cytoplasm and randomly hits a ribosome? What about catalysis? Doesn't catalysis mean non-random?
ExtantFrodo2
ExtantFrodo2 9 dagar sedan
@LAGoff wait, you think that the animations bee line needs to be explained as though it was real? Dude, do not get your science information from animations. The animator does not want to spend the time drawing a truly random walk to illustrate cellular behavior in real-time.
abhinaya sharma
abhinaya sharma 13 dagar sedan
Kindly reminder: All these animations are more than 8 years old.
Allen Oliveras
Allen Oliveras 14 dagar sedan
Drop the Starbucks Netflix and Your 5G phone and maybe u will survive Agenda 21✅
Allen Oliveras
Allen Oliveras 14 dagar sedan
People been trying to do right for so long They can only do what’s left Most don’t know what is coming 🤫
Alto's Music Lab
Alto's Music Lab 15 dagar sedan
they built a working computer in minecraft; we could be minecraft...... molecule-craft some kids toy
Osvaldimar dos Santos
Osvaldimar dos Santos 16 dagar sedan
Joguinhos tetra petris
Papa Alpha
Papa Alpha 16 dagar sedan
Life is art of GOD
Talented Writer
Talented Writer 16 dagar sedan
That walking guy made me think again over my life
jake hensley
jake hensley 17 dagar sedan
Time is running out behind us, but higher dimensions are opening in front of us.
jake hensley
jake hensley 17 dagar sedan
We are the product of subatomic technology.
كيتو حماد نقص وزنك وغير فكرك
كيتو حماد نقص وزنك وغير فكرك 18 dagar sedan
Great video. Thank you very much. There’s only one small comment. A G C T are not nucleic acids. They are organic compounds form nitrogenous basis for the nucleic Acid (DNA). I’m just a student
TELEVISIBLE
TELEVISIBLE 18 dagar sedan
no wonder I am tired all the time 😅
mgsfan15
mgsfan15 19 dagar sedan
It's funny how the language of engineering and design -- the hallmarks of it -- is unavoidable when we observe and study the workings of the smallest parts of life.
mgsfan15
mgsfan15 4 dagar sedan
@ExtantFrodo2 @ExtantFrodo2 Oooo, scary "creationists." "How dare you question the dogma? EVERYONE agrees it was chance!" Apparently you have never been exposed to the wide range of critiques of chance hypothesis from researchers across the spectrum. Almost like you are in some ideological bubble...? Oh, not all of the code is informational? Well how much of it is junk then? 1%? 0.0001%? Your couple paragraphs copied don't give any solution. It is simply more supposition on top of supposition covered up by the miracle word "evolve." "We have figured out how to advance E to F. But we don't know how to get to A." Let's go to another enlightening bit by the Atlantic: "How Do Single-Celled Organisms Have Sex?"
ExtantFrodo2
ExtantFrodo2 10 dagar sedan
@mgsfan15 DNA is not a digital code. It is a particulate one. Do you understand the difference? Genes show that not all code is a purposeful arrangement of characters with specific, meaningful information to it. Sometimes it's just templates mating hand in glove with other templates. *" It is a complicated code that no one can explain the origin of, that is what drives all these processes. "* You've been listening too much to die hard creationists. Flexizymes are de novo ribozymes capable of charging a wide variety of non-natural amino acids on tRNAs. The flexizyme system enables reprogramming of the genetic code by reassigning the codons that are generally assigned to natural amino acids to non-natural residues, and thus mRNA-directed synthesis of non-natural polypeptides can be achieved. In this review, we comprehensively summarize the history of the flexizyme system and its subsequent development into a practical tool. Furthermore, applications to the synthesis of novel biopolymers via genetic code reprogramming and perspectives for future applications are described. Every cell is made of three basic parts: genetic information in the form of DNA or RNA, proteins that provide function and structure, and a surrounding membrane to hold everything together. However, such fatty acid membranes destabilize both in saltwater, where life first arose, and in the presence of the magnesium ions required by RNA. So how did the first cells come to be? A new study suggests it takes one simple ingredient to stabilize the membranes, The Atlantic reports: amino acids. Scientists found that when they mixed these protein building blocks with fatty acids before adding salt or magnesium ions, not only did the membranes stay intact, they also formed double layers that more closely resemble the structure of modern cells, they reported Monday in the Proceedings of the National Academy of Sciences. I'm pretty sure the first replicators were not protein based. Protein making capability evolved after RNA and before DNA. There's no need to invoke other universes to explain processes that are quite natural. There exist natural catalysts which an polymerize RNA into random sequences. In an aqueous environment these begin to break down. That might have been that except that various length fragments encounter the catalysts and get randomly linked to other fragments. This iterative cycle continues and on some planets produces a self-replicating RNA strand which takes over from the catalyst using up certain resources in their environment (nucleobases, sugars, phosphorus) where upon natural selection first begins to play a part in life's history.
mgsfan15
mgsfan15 10 dagar sedan
@ExtantFrodo2 What an explanation you have given... The universal fill-in-the-blank ans