Thanks to all of you who jumped right in and wrote those great comments for last week's post! One of the most exciting things for me about writing this blog is that it allows us to establish a dialogue beyond the classroom on questions or topics provoked by a posting. There were many interesting comments and questions - some of them we worked into class discussions (e.g., phytoplankton blooms) but others, equally interesting, went unanswered. I'd like to use one of those questions as a jumping off point for this week's entry.
Mike asked about the need to create false-color images. Good question! It does seem odd to apply a false color to something that presumably has color. But not everything does emit energy that we can observe as "color".
Think about it. What is "color"? Color is visible light energy. You may remember from 9th grade science, or physics, that the visible light spectrum represents only a very small part of the electromagnetic spectrum of wave energy that travels through our universe. Radio waves, microwaves, infra-red waves, ultra-violet waves, x-rays and gammas rays travel through the universe undetected by human eyes. Yet that energy does exist, and there are times when scientists require a means to "see it".
Probably the most common example of a picture that presents false color, or color not readily seen by the human eye, are those pictures that show different temperatures zones in a geographical area, or weather map. UV (ultra violet) photography allows us to "see" hot areas as red, warmer areas as orange, and cooler areas as blue. This technique is also used to assess houses for insulation efficiency, and heat loss.
A true "false-color image" shows color where no color exists, or applies color to selectively separate parts of an image for analysis. Basically, scientists create a color key. Take a look at the picture at the top of this post. This remarkable picture shows us the nuclei (plural of nucleus) of a zebrafish embryo during its initial 24 hours of development. The image has been falsely colored to provide a key to the activity thats taking place. The green nuclei have locked in place. The orange colored nuclei are in motion - swirling in an ever tightening vortex, hurtling towards the center of the embryo in this initial phase of development called gastrulation; the process of differentiating an outside layer (ectoderm) a middle layer (a mesoderm) and an inner layer (an ectoderm).
Its like rolling a ball of Play Dough in your hands, placing the ball on your desk, punching the ball down, and enclosing the resulting hollow space. It's how life develops from a ball of undifferentiated (unspecialized) cells to an embryo. (That's for all of you who clicked your primary interest in zoology!)
The above image was created with a new technology developed in 2008. By falsely coloring different nuclei, scientists are able to watch processes that had previously been invisible. The single color image appearing above this post shows the end result. Note the cluster of nuclei running longitudinally from the top to bottom poles of the embryo. The false-color image shows us the path the nuclei used to move into position. Pretty cool stuff. I can't think of a better image to illustrate the idea we discussed last week that life has order.
Similarly, by falsely coloring the changing UV energy, scientists can "watch" phytoplankton migrate in the oceans. And by falsely coloring the shift in unseen UV energy emitted by stars, scientists can color and observe the most distant objects in the universe. (Light shifting due to movement is similar to sound shifting due to movement. Think of the difference in a siren's pitch as a fire truck approaches and as it moves further away from you. This is called the Doppler Effect.)
Of course, some of this unseen energy (UV light) is unseen to us, but is in fact visible to other organisms. Birds use the UV light emitted by the sun to navigate along migratory routes. Bees use wavelengths of energy unseen humans to locate flowers for pollination. The need for false-color images is often just a human one. The wavelengths of energy that flow around us are often used, and sensed by a multitude of other organisms for their survival.
So - here's the question I pose to you this week. Look at the zebrafish embryo again. Can this 24hr cluster of cells truly be considered to be "alive"? If so, when did life begin for this embryo? Or has it not yet crossed some threshold over which you would consider it alive? (Boy - talk about provocative questions!) There's obviously no single answer, let alone a "correct" one. We've been talking about the characteristics of life this week, and while its very early in the semester, it's as good a time as any to consider the question of life itself - when do you think life begins?
I'm really interested to read your thoughts on this. Personally, I'm still trying to figure it out myself - so give it a shot!
16 comments:
Individual cells are able to take in and use energy, divide (A form of reproduction? Possibly... depends on your interpretation!), and communicate with other cells (an example being the individual heart cells that Mr. Engler described in class--they were able to beat in-sync when at first each one had its own individual rhythm). If a multicellular organism, like a human, is able to do these things (reproduce, take in and use energy, and communicate, just to name a few) and is considered alive, then why can't an individual cell be labeled as alive?
While I may not believe that an individual cell shares the same thought processes as a human being or more complex creature, it fits the definition of being alive.
(And thanks Mr. Engler for the explanation of false-color images!)
-Mike Diamond
Kind of off topic, but what I found interesting about the lecture today (and semi-related to this blog post) is that fact that the different cells and such can find their ways to each other. These seemingly lifeless and insignificant things. These one celled life forms that create all but alone really can't be anything, are capable of creation and, in a sense, movement. They have no brains, no eyes, no hears, nothing sensory and yet can still band together. Today in the lecture it was the recreation of the RNA, a hypothesis of what might have occurred millions of years ago to form the varieties of life to day. And a few days before the heart cells which when left on the dish began beating as one, and ultimately became one beat. They were able to find each other using some other kind of sense, or knowing. I do not believe that they are living entities on their own, but we do know that they create everything that there is. They are too simple to have this much complexity in my mind.
-Holly Buttrey
I thought that it was really interesting how so many animals use energy that is unseen to us, such as UV light and wavelengths. Not only do animals such as birds and bees use these, but it is essential for their survival. As far as the question is concerned, I don’t see why cells can’t be considered to be alive. Like Mike mentioned, they perform functions of life such as taking in and using energy, regulating their internal environment, dividing to form new cells, and responding to the environment around them. Even though cells are much simpler than animals and humans, I still think that they are alive.
-Amanda O
I believe the cells to be living because they are already growing and developing. There is a belief during pregnancy that some people follow, that considers an abortion to be murder when the child passes a certain point of development and is considered alive. I disagree with this because I think once an organism has been created, even within the first 24 hours of it's existence it has begun to grow in this world and is therefore alive. As Mike said "the cells have begun to take in and use energy."
False-color images, yay! Kinda along the same line as people randomly giving dinosaurs colors since we don't have any idea what they were. Oh well, they probably make them look prettier than they really were, so I'll stick with it.
In regards to the life-thing, I'm still not sure myself. Since there are so many different opinions on when "life" begins. Since nobody really knows, I like to narrow it down to either everything is alive, or nothing is. Personally, I like everything being alive, so in my opinion, yes that embryo with the dinosaur colors is alive.
-Daniel G
I have to say these pictures are a wonderful illistration, and easy to use as an example. As for being alive, I would have to say yes. Though there would be reasons to contradict that, I think I'm going to focus on it being alive. As you spoke of the human heart cells beating in unisin, I think that's when something should be considered alive for a human. Unless there is previous activity within the cell that shows developement. Since you can see the different heat of the cell, I think that the energy is there, it is capable of reproduction/production and action, then yes it is alive. Just like the human heart cells. If it is a sign of an organism that will eventually be a technolly living organism, then yes it should be considered alive. When it comes to humans, I think that once you can sense the activity of the two heart cells, then it should be considered alive. Somewhat with the fish embryo.
Very cool pictures.
-Elsa C.
I don't know as if there will ever be a clear definition of when life actually begins. i mean of course once an organism is born it's alive, but it wasn't "dead" or non-living before it entered into the world. I guess I would have to say that the embryo is living. By creating these false-color images, scientists are able to see that the cells are moving and responding to the environment just like any living organism would. It's hard to think of a blob of cells as "living", but if you think about it, that's really all we are anyways.
There are many ways in which one could try do define when an organism is "alive". However, I don't think there is a clear-cut definition. It seems that even single celled organism can be considered alive because of the functions they are performing. They are taking in energy and using it, just like many people have said. When the embryo has been "born" it begins to adapt to its environment and will start to perform its specific functions. I think with these aspects it seems legitimate to say that the embryo is alive, even if it does not have the same capabilities to that of a human.
First of all, I think this is a hard question, because we are voicing our opinions about what we value as life or not. Although the cell does not have a thinking process at this time, it will once it is fully developed. So, therefore it is alive, but not in its full form.
I agree - it IS a hard question, which is why I value everyones thoughts on this. As I noted in class, there are no "right or wrong" answers - rather a spectrum of thought that reflects our classroom community.
Thanks for posting your thoughts!
I'm not going to lie; my favorite part of this post was the play-doh metaphor! Of course, learning about why they make pictures those funny colors was interesting as well. I'd like to know more about other cases where they would change the natural colors of an image to make a point (I guess anyone with Photoshop could do that...)
As for the question about life, I'm going to stick with a firm "I don't know". And I'm going to quote Austin Cline:
"It's okay not to know an answer, but it's not okay to pretend you know the answer or to make up an answer simply because it fits in with your preconceptions."
Since I obviously don't know the answer, any way I tried to respond to the question, I would be influenced by my own preconceptions. And that wouldn't be the right way to go about it.
So, again, I don't know.
And thank you for the informative and thought-provoking post!
As odd as it sounds, this question is one that I think about frequently. It's a dangerous question to pose to me, because I'll talk in circles and never come to a conclusive opinion. According to our definition of life, any single living cell is 'alive'. In most cases, however, we humans do not value bacterial/prokaryotic life as highly as eukaryotic life. Bacteria are just as alive as a zebrafish, and yet it is difficult to give the death of a bacteria import. If we do not place value on the life of a single-celled organism, how can we profess to value a tiny cluster of cells? Does the genetic material inside a cell automatically make a zebrafish cell more important than a bacterial cell? These are all questions for which I have no answers. Maybe they have no answers. Scientists and philosophers classify and quantify life, but is it really possible to discover the exact moment that separates life from something else? I'm going to side with Rebecca and end with a firm "I don't know."
Jennie M.
I wonder if the rapid asexual reproduction effort exerted by prokaryotic organisms has something to do will our low level of concern for their well being. The more complex an organism is and/ or the longer it takes to develop the more we humans seem to value it. Time is an interesting measure of value since we all have a set amount of time on earth. We (and those who follow after us) may not get another opportunity to meet organisms that take 100s + years to develop if we destroy them today. But perhaps I’ve gone astray with value judgment rather than focusing on when life begins. I’d agree with many people who’ve posted above that life technically begins at the cellular level but when that life starts to have value is a deeper harder question to answer.
Hey Mr. E, sorry this is late.
I beleive there should be a cut off date as to whether somthing can be considred alive. This "assumption" or "descion" or "belief" (it's not really any of those, more of a combination of the three) Is somthing I came to a "conclusion" about based on the knowledge I posses, and have been provided with.Some people may think I'm witchy, or just can't empathize, or some other thing that makes me short sited. but I think that the world is way way way over populated. So, like in the past when things go too well, they have to be stopped. Our life expectancy is so high, our health care (though expensive) is top notch.We need somthing to slow us down our we'll demolish any chance of life at all. so all these "incurable" diseases are set in place for a reason. to contain or expansion.
Da Cleava
Hello, I am sorry this is late, too. I am still not used to doing homework online. And since it is homework that doesn’t need to be announced, I keep forgetting it.
However, I think this is a very interesting topic. When does life begin? As some other students said, one could argue that a single cell responds to the environment, is able to reproduce and take in and use energy. But it doesn’t seem right to me to consider a single cell a living thing. I always thought of myself as one living being and not several trillions.
Scientifically, the embryo seems to be considered a living thing. It is made of cells, obtains and uses energy, grows and develops, responds to its environment, adapts to its environment, and it will eventually reproduce. Just the fact that it is developing and growing makes it different from dead things. But when I don’t think about scientific definitions, I would not consider it a living thing. When I think of something being alive, I think of something like a trout swimming in a brook. It is hard to make a point, but I think this embryo is about to become alive. You cannot say it is dead, but for me it is too early to consider it alive.
I am also amazed, that we need to make “false” color pictures to understand and see things like the wavelength of energy. Animals that seem to be pretty primitive compared to the human race have no troubles sensing these things. I think it is nice to know, that animals are superior to us in some ways.
It is amazing to think about all of the other wavelengths of light the human eye cannot see. Humans can see what is visible to their eyes its hard to wonder what anything else might look like because our mind can not comprehend it. In the idea people cannot determine what is alive or what is dead. Most people would think that if something isn't moving it is dead, but we know things will sleep or lay dormant, and that doesn't mean they are dead. Therefore it is hard to define life without running into exceptions.
Andy H.
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