Tough question.

Discussion in 'Biology & Genetics' started by Klutch, Jan 7, 2003.

  1. Klutch Registered Member

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    You are given four test tubes containing purified biological macromolecules. The test tubes are unlabeled except for a number between 1 and 4. You are told that one test tube contains a protein, one contains a lipid, one contains a carbohydrate, and one contains a nucleic acid. You then perform some tests on the macromolecules and collect the following information: a. Test tubes #2 and #4 contain nitrogen, but the other tubes do not. b. The contents of test tube #3 are not soluble in water, but the contents of the other test tubes are soluble in water. c. The contents of test tube #1 can be broken down into subunits that are all exactly identical to each other. d. The macromolecule in test tube #2 is found to have a globular shape. What are the identities of the macromolecules present in the four test tubes? Explain how you arrived at your decision.


    Anyone with an answer to this, please do not hesitate. I have been trying to figure it out for quite some time now..
     
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  3. spuriousmonkey Banned Banned

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    i can start with it.

    Test tubes #2 and #4 contain nitrogen: since only proteins and nuciec acids have nitrogen, they most be in these tubes.

    lipids are not soluble in water, therefore #3 must contain lipids.

    #1 must then contain carbohydrates (because of previous statements). and it is build up out of sugar units (probably)

    #2 has a globular shape...hmmm....if they mean on a molecular level then it must be protein, since DNA is linear. But then again, the first statement talks about the presence of nucleic acids. That is only the individual building blocks, then the question is if an individual nucleic acid is globular or not. Probably not...so:

    #1 carbohydrates
    #2 protein
    #3 lipids
    #4 nucleic acid
     
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  5. NenarTronian Teenaged Transhumanist Registered Senior Member

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    i concur to the above, good job seriousspunkie.

    Hope we didnt just give you the homework, Klutch?
     
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  7. pumpkinsaren'torange Registered Senior Member

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    i think you guys just gave him the answer to his homework.

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  8. Idle Mind What the hell, man? Valued Senior Member

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    Although I agree with the order that was discussed, carbohydrates can contain Nitrogen. There are sugars such as glucosamine and galactosamine which have an amine group attached to them.
     
  9. spuriousmonkey Banned Banned

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    and are all proteins really globular?
     
  10. ElectricFetus Sanity going, going, gone Valued Senior Member

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    no each individual peptieds is not. Many protiens (made of many peptieds) will infact form into groups with other proteins... this is globular.
     
  11. Idle Mind What the hell, man? Valued Senior Member

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    Well, for the purpose of this lab (or whatever it happens to be), it's really more a 'best fit' type scenario. Not all proteins are globular, but it is most likely that the protein fits that description.
     
  12. pumpkinsaren'torange Registered Senior Member

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  13. ElectricFetus Sanity going, going, gone Valued Senior Member

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    those are Alpha helix and Beta sheets. Globular means when a protein group together to form a "Globular" structure.
     
  14. Idle Mind What the hell, man? Valued Senior Member

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    That's true, however somewhat incomplete.

    Alpha helices and Beta sheets are the secondary structure of proteins. Tertiary structure is when the protein folds into a 3-D globular shape. Quarternary structure is when multiple subunits group together (which is also globular). So yes and no.
     
  15. spuriousmonkey Banned Banned

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    lets make the situation even more complex.

    DNA is not commonly found in linear form. I gather that we are talking about purified samples here, so this suggests that no DNA folding/scaffold proteins are present such as histones, but:

    what if RNA was in the tube instead of DNA.

    some small RNAs are enzymatic and function like enzymatic proteins.
    they are also folded and form a similar 'globular' form.


    the nice thing about textbook questions is that they sometimes can only be answered on a textbook level and when you really start thinking about them, they gain so much complexity that they might be called bullshit.
     
  16. spuriousmonkey Banned Banned

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    what about membrane proteins...they don't seem to be very globular even on a tertiary level.
     
  17. Idle Mind What the hell, man? Valued Senior Member

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    That's true, I shouldn't have generalized, but I wanted to get across the point a protein doesn't have to have multiple sub-units to be globular.
     
  18. spuriousmonkey Banned Banned

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    i guess i meant quartenary, when i said tertiary...

    i didn't realize you people are not able to read my mind

    but anyway...RNAs are not always linear
     

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