The Cell Brain

[stevo247]

What part of the cell would be considered it's brain? Would it be the nucleus, the membrane, or would the whole cell be analogous to a brain?

[thedarkshade]

Well, the nucleus controls everything, so it's kinda main control center. You can think of it as the brain cell too, I see no problem with that!

[Paralith]

I don't think anything in the cell would be a good analogy to the brain. The brain actually takes in, processes, and stores information about the outside world. There is no particular structure in the cell that performs this type of task.

[Mr Skeptic]

I don't think anything in the cell would be a good analogy to the brain. The brain actually takes in, processes, and stores information about the outside world. There is no particular structure in the cell that performs this type of task.

 

But cells do exactly that. They take in sensory input, and switch genes on or off based on that. They have their own daily cycle, that they can retain even without input from the sun. Some of the genes switched on or off get passed on to the offspring, essentially telling their offspring about what has happened. All this is mostly due to the nucleus, of course.

 

However, single cells cannot deal with "abstract" data of any sort as far as I know. So "control center" would be better than "brain" to describe the nucleus.

[iNow]

Is not a "brain" by definition a "collection" of cells?

[stevo247]

One of the definitions I found for brain in the websters dictionary was "the organ that perceives sensory impulses and regulates motor impulses".

 

The biology on-line dictionary defined brain as:

 

One of the two components of the central nervous system, the brain is the centre of thought and emotion. It is responsible for the coordination and control of bodily activities and the interpretation of information from the senses (sight, hearing, smell, etc.). That part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord.That which is responsible for one's thoughts and feelings; the seat of the faculty of reason; his mind wandered; I couldn't get his words out of my head. Part of the central nervous system involved in regulating and controlling body functions while interpreting information from the senses transmitted through the nervous system.

 

http://www.biology-online.org/dictionary/Brain

[iNow]

Well, considering the definition of brain which you just shared, I am rather confident that the cell does not have one. You are welcome to, in your imaginatation, classify any of the cell structures as it's "brain," however, that classification won't like translate to the actual research being done in the field.

 

 

My guess is that "brain" is just not the correct word for what you are asking, as much of the control of the cells functions is regulated by physics and chemistry itself (think osmosis and equilibrium).

 

Sorry if I'm totally missing your point. If that's the case, feel free to completely disregard my point (and hopefully clarify yours).

 

Cheers.

[Sisyphus]

Well, considering the definition of brain which you just shared, I am rather confident that the cell does not have one. You are welcome to, in your imaginatation, classify any of the cell structures as it's "brain," however, that classification won't like translate to the actual research being done in the field.

 

 

My guess is that "brain" is just not the correct word for what you are asking, as much of the control of the cells functions is regulated by physics and chemistry itself (think osmosis and equilibrium).

 

Sorry if I'm totally missing your point. If that's the case, feel free to completely disregard my point (and hopefully clarify yours).

 

Cheers.

 

Obviously cells don't have brains, but I thought the question was more like what is analogous to the brain. It might be a rough analogy, but I would have to give credit to the nucleus. Yes, it's ultimately "regulated by physics and chemistry itself," but so are brains.

 

I'm just thinking about single-celled organisms like a paramecium or an amoeba, and how they sort of respond to stimuli, and how they have such enormous genomes. That's as far as my thought process can go, because a)I'm not a biologist and b)I'm pretty sure the mechanisms are only vaguely understood anyway. But still, it is suggestive, no?

[insane_alien]

well, not all celss have a nucleus. prokaryotes and archaea(sp?) do not have nuclei, or any significant internal structure.

[iNow]

Obviously cells don't have brains, but I thought the question was more like what is analogous to the brain.

 

I agree, I'm pretty sure that's what the OP is after, but since the only answer could possibly be "something analogous," I'd hoped to get some more information. The question is a cool one, but it wasn't very precise so it was difficult to really see what Stevo is getting at.

 

Insane_alien is correct too, in that not all cells have the same structures. So... there's another area of uncertainty which could be cleared up pretty quickly. Right now, for all we know, Stevo is talking about jail cells, or coordinates on an Excel spreadsheet.

[thedarkshade]

I'd go with Sisyphus here!

It's not about a literal brain of the cell. It's just a control center where the function of the cell is regulated, and at this point nucleus (genes to be more exact) is the one!

 

Everything is controlled by our genes and as they are located in the nucleus, then there you get the brain of the cell.

 

It truly is a rough analogy but not so hard to be understood!

[stevo247]

I can appreciate the desire for the clarification of terms. That’s sort of what I am trying to do with the term “brain”.

 

Clearly, the functioning of a bug brain, or a bird brain does not reach the range of capabilities of the human brain. But in regards to each type of organism, the brain serves a common function. The definitions that seems most appropriate so far is “the organ that perceives sensory impulses and regulates motor impulses” and “the part of the central nervous system involved in regulating and controlling body functions while interpreting information from the senses transmitted through the nervous system.

 

Since I am interested (as a layman) in the origin and development and of “the brain”, I started wondering what type of organism has the most primitive style brain. Recently, like yesterday, I read about the planarian. It’s a freshwater flatworm that’s used as a model of the central nervous system in higher organisms. This organism shows primitive “cephalization” and is considered to be one of the simplest brains. It also has eyes that respond to light! So is “cephalization” the criteria for possessing a brain? It seems to make sense that cephalization is the origin of the form of the organ ” brain”, or head brain. But what about the blind uncephalized worm that has a nervous system, and is perceiving sensory impulses and regulating motor impulses? What is organizing that function? I don’t know.

 

From there, it’s not too much of a stretch (then again, maybe it is) to go back to a primitive eukaryote unicellular organism like a paramecia. From what I can understand so far, paramecia have organelles that perform similar functions as multicellular organisms, i.e. digestive system, immune system, reproductive system, etc. Albeit, they are primitive representations. Since they can sense and respond to external stimuli, it would appear that they have some sort of primitive nervous system. Would the nervous system (whatever form it takes on that scale) be comparable to a brain? What is the relationship of this nervous system, to the nucleus and the DNA? What is the relationship of this nervous system to the membrane? I don’t know. The membrane itself, also seems to be very sophisticated in it’s function and structure, in terms of sensing and determining what to let in and what to let out. Even the prokaryote, without a nucleus, demonstrates a perception of sensory impulses and regulation of motor impulses. Maybe the most primitive living cell constitutes the original “brain”.

 

This is something I found interesting from General Systems Thinking.

 

“By observing various types of systems and studying their behavior, we can recognize characteristics that are common to all systems. Once we have identified and described a set of concepts that are common to the systems, and observed and discovered among some of them certain relationships, we can construct from them GENERAL SYSTEMS PRINCIPLES. Thus, a system principle emerges from an interaction/integration of related concepts. Next, we are in the position to look for relationships among principles and organize related principles into certain conceptual schemes we call SYSTEMS MODELS. This process of starting from observation and arriving at the construction of systems models constitutes the FIRST STAGE of developing a systems view.”

[stevo247]

Here is a decent link for info about the nervous system:

 

http://www.britannica.com/oscar/print?articleId=110703&fullArticle=true&tocId=75826

 

"The responsiveness of a single cell can be illustrated by the behaviour of the relatively simple amoeba. Unlike some other protozoans, an amoeba lacks highly developed structures that function in the reception of stimuli and in the production or conduction of a response. The amoeba behaves as though it had a nervous system, however, because the general responsiveness of its cytoplasm serves the functions of a nervous system. An excitation produced by a stimulus is conducted to other parts of the cell and evokes a response by the animal. An amoeba will move to a region of a certain level of light. It will be attracted by chemicals given off by foods and exhibit a feeding response. It will also withdraw from a region with noxious chemicals and exhibit an avoidance reaction upon contacting other objects."

 

 

"If later organisms evolved from single-celled ancestors, then there must have been some system for the transmission of information from one evolutionary stage to the next. These conditions have been defined as: (1) a stable means for encoding, transmitting, and decoding characteristics from one generation to the next, (2) the possibility of alterations in the code taking place by mutation or sexual recombination, and (3) a means of selecting only those characteristics for transmission that are favourable for survival. As mentioned in the section Stimulus-response coordination, protozoans (single-celled organisms) move toward places that are favourable for survival, such as areas with optimal conditions of light and temperature. As the metazoans (multicelled organisms) developed, entire groups of cells probably tended to move toward favourable conditions, and when the number of cells became very large, a system of internal communication—in effect, a nervous system—developed. Two general types developed: the diffuse nervous system and the centralized nervous system"

[CDarwin]

I always thought of the nucleus as more of a warehouse than anything else. The actual "controlling" of the cell is done by the genetic material, be it prokaryote or eukaryote. If you want something analogous to the "brain," I'd say that would be it.

 

In any event, you certainly shouldn't think of the brain as having evolved from any part of a cell. "Brains" in that sense are purely multicellular phenomenon. Hence the term "analogous" and not "homologous."

[Mr Skeptic]

I always thought of the nucleus as more of a warehouse than anything else. The actual "controlling" of the cell is done by the genetic material, be it prokaryote or eukaryote. If you want something analogous to the "brain," I'd say that would be it.

 

But the genetic material itself does nothing. It's more like an instruction manual. The proteins in the nucleus receive signals, and look up the appropriate instructions. The proteins switch genes on or off, send messenger RNA to the ribosomes, etc. So the chromatin, that makes up the protein+DNA complex would be more analogous to a brain than just the DNA.

[CDarwin]

So the chromatin, that makes up the protein+DNA complex would be more analogous to a brain than just the DNA.

 

That's fair.

[stevo247]

The definition of “brain” that I’ve been using is “the organ that perceives sensory impulses and regulates motor impulses” and “the part of the central nervous system involved in regulating and controlling body functions while interpreting information from the senses transmitted through the nervous system.” Based on that definition, I find it difficult to equate the nucleus and the function of the genes and chromatin, with the function of a “brain”. I would think that something analogous (or homologous) to a cellular nervous system would be a more functional representation. I can appreciate the belief that the nucleus (genes and chromatin) of the cell is analogous to the brain of the cell. I am sure that most would probably agree with you. It just does’t make sense to me yet. I just can’t see how the nucleus co-ordinates the integration of sensory impression and motor activity.

[stevo247]

I find this idea very interesting:

 

Guenter Albrecht-Buehler

We have always accepted that the central control organ of an organism directly or indirectly tells the molecules of the rest of the body what to do in order to generate the myriad of its biological actions. Only in the case of cells most biologists believe differently. They think that the interaction of the macromolecules inside a cell generates the myriad of cell functions, and that studying them will explain the cell functions. I believe the opposite. Just like in

the case of metazoa, the molecules of a cell are being told by a central information processing organelle what to do in order to generate cell functions. As you can see from my website, for the past 30 years I have tried to analyze the 'chain of command' in the case of cell motility. According to this work, the 'brain' of the cell (=centrosome?) collects visual information with its embedded 'eyes' (=centrioles), sends commands along 'nerves' (=microtubules) to the 'muscles' (autonomous cortical units, called microplasts) that initiate the molecular interactions that ultimately lead to extensions, ruffling, blebbing, retractions, etc.

 

http://www.basic.northwestern.edu/g-buehler/htmltxt.htm

 

 

 

As a major microtubule-organizing center, the centrosome, together with the embedded centrioles and connecting filaments (or microtubules), has lately been proposed to be the "brain" of a cell. Although there are a lot ofworks to be done to test this hypothesis, emerging data have suggested that this centrosome-centered "cell brain" is playing increasingly important roles in cell control. Genes seem not to tell the whole story, despite the commonly held view that genetic alteration is the cause of most medical problems including cancer development. Although the mechanisms through which gene expression and protein synthesis are regulated remain to be studied, current advances in our understanding of the roles of the centrosome in the regulation of DNA synthesis, DNA repair, cell cycle, apoptosis and in the maintenance of genetic stability are challenging our tradition thoughts. Genetic alterations may be repaired by the centrosome-centered "cell brain"-mediated self-defense, but the cell brain defects intend to cause genetic alterations, which, in turn, may result in cancer development. Further understanding of the roles of the centrosome/cell brain in these and other new aspects are becoming very helpful in comprehending why and how medical problems including tumors develop. Meanwhile, it suggests that great attention should be given to the centrosome/cell brain, instead of gene alone when treating medical problems, which is discussed in this paper on the basis of cell brain theory and may prove helpful in shedding light on the often paradoxical observations seen in cell control, particularly in cancer development.

 

 

http://cat.inist.fr/?aModele=afficheN&cpsidt=17041280

 

http://www.lanjin.cn/theory.php?language=1

[stevo247]

Here is another interesting perspective:

 

Cellular life is sustained by tightly regulating the functions of the cell’s physiologic systems. The expression of predictable behavioral repertoires implies the existence of a cellular "nervous system." This system reacts to environmental stimuli by eliciting appropriate behavioral responses. The organelle that coordinates the adjustments and reactions of a cell to its internal and external environments would represent the cytoplasmic equivalent of the "brain."

 

The notion that the nucleus and its genes are the "brain" of the cell is an untenable and illogical hypothesis. If the brain is removed from an animal, disruption of physiologic integration would immediately lead to the organism's death. If the nucleus truly represented the brain of the cell, then removal of the nucleus would result in the cessation of cell functions and immediate cell death. However, experimentally enucleated cells may survive for two or more months with out genes, and yet are capable of effecting complex responses to environmental and cytoplasmic stimuli (Lipton, et al., Differentiation 1991, 46:117-133). Logic reveals that the nucleus can not be the brain of the cell!

 

 

Studies on cloned human cells led me to the awareness that the cell’s plasmalemma, commonly referred to as the cell membrane, represents the cell’s "brain." Cell membranes, the first biological organelle to appear in evolution, are the only organelle common to every living organism. Cell membranes compartmentalize the cytoplasm, separating it from the vagaries of the external environment. In its barrier capacity, the membrane enables the cell to maintain tight "control" over the cytoplasmic environment, a necessity in carrying out biological reactions.

 

 

The cell membrane is an organic information processor. It senses the environment and converts that awareness into "information" that can influence the activity of protein pathways and control the expression of the genes. A description of the membrane’s structure and function reads as follows: (A) based upon the organization of its phospholipid molecules, the membrane is a liquid crystal; B) the regulated transport of information across the hydrophobic barrier by IMP effector proteins renders the membrane a semiconductor; and © the membrane is endowed with IMPs that function as gates (receptors) and channels. As a liquid crystal semiconductor with gates and channels, the membrane is an information processing transistor, an organic computer chip.

 

 

The cell is a carbon-based "computer chip" that reads the environment. Its "keyboard" is comprised of receptors. Environmental information is entered via its protein "keys". The data is transduced into biological behavior by effector proteins. The IMP BITs serve as switches that regulate cell functions and gene expression. The nucleus represents a "hard disk" with DNA-coded software. Recent advances in molecular biology emphasize the read/write nature of this hard drive.

 

http://www.brucelipton.com/article/insight-into-cellular-consciousness