Why do we age and not live forever? Is immortality possible and does it exists?
Phoenix, Marvel Comics
Egyptian Phoenix (Bennu)
Chinese Phoenix (Fenghuang)
Most of us would think of a super human being or a god when we think of immortality. The media has portrayed immortality in a variety of ways; from a entity that ages but can’t die from physical injury or old age or one that stops aging at a particular stage and stays that way forever and cannot die no matter what. One popular immortal mythical creature portrayed in the media and many cultures around the world is the Phoenix; once it "dies" it rises from its ashes and lives again a new life. In either interpretations of immortality, it involves something supernatural. Although there are many ways to interpret immortality, I will focus on it at a cellular level; a cell that cannot die from aging but can die from other things such as starvation, physical trauma or pathogens (disease causing microbe).
First of all, why do we age? One major explanation or theory to why we age is that the telomeres in our cells shorten whenever it divides. Each one of our cells has DNA. Telomeres are DNA themselves, but are located at the end of the entire DNA molecule, or chromosome, and are composed of repeated sequences (repeated sequences meaning repeating in any of the 4 components of DNA: A, T, G, and C in a particular order, for instance in humans it is many repeats of just TTAGGG over and over again). The main purpose of telomeres is to protect our genes, our genetic information, from cleavage damage from cell division or other processes; when genes are destroyed they become cancerous or are unable to make useful proteins needed in life.
Cell division is important for growth, injury repair and many other things; whenever a cell divides its telomere gets cut and so does a portion of the lifetime; our cells that makes us age and therefore we age. When a cell divides, it needs to replicate its DNA so it can pass it on to its progeny cells, since the telomeres in DNA gets shorten during this process both progeny cells get a shorter DNA than their parent cell and therefore a shorter life. This is the reason why telomeres are at the end of the DNA so that it gets destroyed instead of DNA that stores useful information.
Telomeres indicated by red regions in these chromosomes
If our cell’s DNA did not have telomeres, then it simply would not divide or our genes would be destroyed after only a couple divisions. According to the Hayflick Limit, a theory that states the number of times a cell can divide before it dies or stops dividing, a human cell can divide 50-70 times before it stops and dies. Basically, when the telomeres are gone and done with, so is the cell. It is not clear to why our cells cannot retain the same telomere length we were born with and why it shortens after each cell division but we do know that is it not from a damaging process. As Dr. Bill Andrew describes it “it’s not a wear and tear mechanism, it’s simply due to the fact that our cells lack the ability to replicate the very ends of the chromosomes and is a passive process.” Amazingly, your age can be estimated just by looking at the telomere lengths in your DNA. One way in which the cell reverses this process is by an enzyme called telomerase, which elongates the ends of telomeres that have gotten shorter. However, as the cell gets older the activity of telomerase weakens.
So are there living things that are immune from the damaging processes of aging and can live forever (can’t die from old age)? Yes.
Cancer cells are a prime example of immortal living entities in biology, and yes they really are immortal especially if kept in a controlled laboratory environment where nutrients are constantly replaced, waste is constantly removed, and are kept from outside sources that can cause them trauma. Okay, so there's not supernatural stuff happening here, but it's still pretty damn amazing the fact that these cells can never age. The simple reason why cancer cells are immortal is because their telomeres don’t get shorten; they always have an overabundant supply of active telomerase. They can divide for an infinite number of times, defying the Hayflick Limit, never age and can live forever if they don’t get fatally injured or starve to death. Not only are cancer cells immortal but they also divide rapidly. This is why they cause tumors, because they don’t die from aging and just keep on dividing infinitely to create a huge blobby mass.
One famous line of immortal cells used in research is the HeLa Cells, named after Henrietta Lacks who is the source of these cells. She died from cervical cancer in 1951; the cancer cells obtained from her, without her permission, have been dividing since her death and used in research labs all over the world. What makes these cells and other cancer cells more amazing is that they can survive outside of their source organism, unlike most normal cells that die shortly when taken out of the body.
The immortal HeLa Cells
Other examples of cells that don't show signs aging and can be immortal are sex cells and bacteria. In sex cells, it is almost the same biology behind cancer cells, their telomeres don't shorten due to active telomerase; however, I believe the mechanisms behind why these cells don't age is less known than cancer cells. In bacteria it is much different; MANY, BUT NOT ALL, bacteria have a single circular chromosome. When bacteria divide they replicate their entire chromosome and if there are no errors in the process, there is no loss of genetic material.
Egg and sperm
Bacteria
With the discovery and knowledge of telomeres and telomerase there are a lot of crazy things certain scientists are probably trying to do (this alone can be the topic of another post itself). Of course, one way benefit of this knowledge would be to treat cancer. In studies done with mice with cancer, taking away telomerase from the cancer cells caused the death of them. Next for us is to find a way to destroy tolemerase in human cancer cells. There's also this idea of how living forever may be possible. However; when I asked many of my friends if they wanted to live forever many of them said no.
I like how you intertwined biology with the history of immorality. Doing this interested me into reading more; also the pictures and the videos really helped understand the topic you are trying to teach me. Keep up the good work on merging more than one topic to emphasize your love for biology.
On a serious note, does it mean we can know our life expectancies if were able to figure out how many times all our cells can duplicate. And if it stops, it would mean the end of our life cycle?
when spoken of immorality, i instantly thought of all the supernatural and crazy asian dramas that i watch normally. something that came up instantly was back in china during the kingdoms when the evil king thought of many ways to come up with a medication that can enable him to never grow old. but anyhow, as i read more through this post, i did as well think of cancer treatments as well ... it made me think that cancer is even harder to treat ...
Your blog is really cool! and I enjoyed reading this post about immortality. I like how you incorporated short videos to further explain what you said in the paragraph above them, I felt almost as if I was in a cool biology class with a teacher who was both passionate and knowledgeable, and interested in the topic; wanting to share his great interest with others.
Your interest in biology definitely comes through in your writing in a way that is easy for someone who may not share the same passion of biology, such as myself, to understand
Wow, this is actually really interesting. I like how you back up your facts with interesting pictures and videos. I think that they really contribute to your blog in a positive way. I can tell that this topic really interests you, especially by your frequent long posts. I would definitely like to read more about this topic.
Thanks everyone. And Stephen, cancer is not a good thing, but if we can control it without radiation or anything it would be great. The only way I can think of if we were to be made immortal is if we find a way to make our cells divide without losing the telomeres or the important DNA. As I said before, cancer cells divide way much more fast than a normal cells so we have to find a way where our cells are doing the same things they are now but without losing the telomeres when they divide. Because if we make all our cells immortal like cancer that divides like crazy we would be one big blob of mass.
For your second question, yes. Not all types of cells divide at the same rate or does not have the same Hayflict Limit. But one thing I didn't mention is that some cells do not divide once you reach a certain stage, such as heart muscle cells, or spinal chord cells. So if scientist used this method to determine life expectancy I think it would be very hard and take very long to do since you have to look at each type of cell in the body.
I found this post really intersting, because its something I've ask myself. Yet I still wonder why do some individuals seem to age faster than others? For example there are some individuals that seem to be older than the age they really are and others seem yonger. Is this because some cells take longer at dividing or not?
Nice stuff here. I've heard from a lot of other places that things like antioxidants can help prevent some of these genetic errors and thus play a part in slowing aging (physically). What's your take on this?
Antioxidants protect cells from damage from the external environment so it may prevent cells from premature death; I don't know much about antioxidants since I don't study them. But from what I do know as of now it has nothing to do with telomerase which is the major determinant factor in aging. A short theory, you can have as much antioxidants as you want but your cells are still going to be dividing and your DNA is still going to get shorter from those divisions.
I like how you intertwined biology with the history of immorality. Doing this interested me into reading more; also the pictures and the videos really helped understand the topic you are trying to teach me. Keep up the good work on merging more than one topic to emphasize your love for biology.
ReplyDeleteSo if we can control cancer, WE CAN BE IMMORTAL?!
ReplyDeleteOn a serious note, does it mean we can know our life expectancies if were able to figure out how many times all our cells can duplicate. And if it stops, it would mean the end of our life cycle?
when spoken of immorality, i instantly thought of all the supernatural and crazy asian dramas that i watch normally. something that came up instantly was back in china during the kingdoms when the evil king thought of many ways to come up with a medication that can enable him to never grow old. but anyhow, as i read more through this post, i did as well think of cancer treatments as well ... it made me think that cancer is even harder to treat ...
ReplyDeleteYour blog is really cool! and I enjoyed reading this post about immortality. I like how you incorporated short videos to further explain what you said in the paragraph above them, I felt almost as if I was in a cool biology class with a teacher who was both passionate and knowledgeable, and interested in the topic; wanting to share his great interest with others.
ReplyDeleteYour interest in biology definitely comes through in your writing in a way that is easy for someone who may not share the same passion of biology, such as myself, to understand
Wow, this is actually really interesting. I like how you back up your facts with interesting pictures and videos. I think that they really contribute to your blog in a positive way. I can tell that this topic really interests you, especially by your frequent long posts. I would definitely like to read more about this topic.
ReplyDeleteThanks everyone. And Stephen, cancer is not a good thing, but if we can control it without radiation or anything it would be great. The only way I can think of if we were to be made immortal is if we find a way to make our cells divide without losing the telomeres or the important DNA. As I said before, cancer cells divide way much more fast than a normal cells so we have to find a way where our cells are doing the same things they are now but without losing the telomeres when they divide. Because if we make all our cells immortal like cancer that divides like crazy we would be one big blob of mass.
ReplyDeleteFor your second question, yes. Not all types of cells divide at the same rate or does not have the same Hayflict Limit. But one thing I didn't mention is that some cells do not divide once you reach a certain stage, such as heart muscle cells, or spinal chord cells. So if scientist used this method to determine life expectancy I think it would be very hard and take very long to do since you have to look at each type of cell in the body.
I found this post really intersting, because its something I've ask myself. Yet I still wonder why do some individuals seem to age faster than others? For example there are some individuals that seem to be older than the age they really are and others seem yonger. Is this because some cells take longer at dividing or not?
ReplyDeleteNice stuff here. I've heard from a lot of other places that things like antioxidants can help prevent some of these genetic errors and thus play a part in slowing aging (physically). What's your take on this?
ReplyDeleteAntioxidants protect cells from damage from the external environment so it may prevent cells from premature death; I don't know much about antioxidants since I don't study them. But from what I do know as of now it has nothing to do with telomerase which is the major determinant factor in aging. A short theory, you can have as much antioxidants as you want but your cells are still going to be dividing and your DNA is still going to get shorter from those divisions.
ReplyDelete