Questions about microscopic life

Discussion in 'Biology & Genetics' started by Stephanoceros, Jan 8, 2010.

  1. Stephanoceros Registered Member

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    2
    Hello!
    First of all, I am nothing short of a complete novice when it comes to the subject of microscopic life. I only recently took it upon myself to learn everything I can about the subject, and in the natural course of my research a number of questions have popped up. I appeal to the knowledge and experience of other people visiting this forum to help me clear up some confusion that I have about a few things. Any effort to accomplish this will be greatly appreciated.
    In researching Cyanobacteria, I keep reading about it existing in unicellular forms and colonial/ filamentous forms. Take Oscillatoria for example- in all of the images I see of it, it is a single green strand, usually clumped together with other green strands. What I"m wondering is if each strand is a single individual, or if the rectangular cells that make up the strand are themselves individual organisms making up a colonial strand. I guess I'm hazy on what constitutes an individual in this sense. Or with Nostoc, there are the grape-looking colonies, and inside are the beaded string filaments. Are each of the beads a separate organism, or is the string as a whole just one living thing? The lines seem to be blurred when it comes to free-living individuals and colonies.
    I recently encountered the same confusion with Fungi. Since all the text I read referred to fungi as colonies, I assumed that each hypha is a separate individual, and they all link and work together as a colony. I now understand that it's an isolated mycelium which constitutes a single fungal organism, with the mushrooms being its various appendages for reproduction (I HOPE I'm correct by assuming this). So why is the term 'colony' applied to fungi?
    Again, I thank you for bearing with me and can't wait to hear your responses!
     
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  3. Fraggle Rocker Staff Member

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    When you're dealing with single-cell life, then each cell is an organism and there's no two ways about it. But with multicellular organisms it's not so clear. Sure, maybe it is with vertebrates--although what do you call the two-headed snake? But with the lower lifeforms it's not so easy to decide where one individual collection of cells stops and the next one begins. The worm that you can chop in half and each half goes its merry way?

    It's even harder with plants, and fungi are probably closer to plants than to any of the other kingdoms. You're just running into the limitations of the language. Don't get hung up on that as a science problem; it's just a language problem.

    -- The Linguistics Moderator
     
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  5. John M Registered Senior Member

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    on fungi

    Hi Stephanoceros

    Don't sell yourself short and don't buy too many others long. I'm no expert or student of fungi, but let me pass along some thoughts on the subject anyway. First of all I don't believe I'd call them colonial, certainly not in the sense of Volvox or a coral head. Nor would I think of them as microscopic although their spores and hyphae might be. Most interesting, which you've probably come across already is that fungi are more closely related to animals than to plants and are considered by some to form their own kingdom. Maybe we're just mushrooms with legs.

    A search on Google brought up three articles at the very top. Fungi: life history and ecology (ucmp.berkeley.edu/fungi/fungilh) by UCMP Berkeley and Fungi (tolweb.org/fungil) by Tolweb are very good and to the point. The Wikipedia article (wikipedia.org/wiki/Fungus) at the very top is more lengthy and as is often the case excessively linked.

    Any way good luck with your pursuits

    John M
     
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  7. DRZion Theoretical Experimentalist Valued Senior Member

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    Hi Stephanoceros,

    I have noticed this on photos as well - the filamentous bacteria are often segmented. There several possibilities as to what the structure of these microbes may be. There are certainly microbes that are elongated - many times longer than they are wide (rod shapes and helical shapes come to mind). There are also fungi that consist of many nuclei contained within a cell wall, and these are also filamentous. It may be possible that as the cells fuse together they leave behind some kind of wall which results in segments.

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    These are neurospora cells, which often have multiple nuclei (heterokaryons). This is in some sense a clever mechanism that makes this specie more resistant to knockout mutations, but likely more susceptible to parasites and other maladies.
     
  8. Hercules Rockefeller Beatings will continue until morale improves. Moderator

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