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How would you answer this Biology question?

Discussion in 'MCAT Study Question Q&A' started by dancerdoc89, Aug 1, 2011.

  1. dancerdoc89

    dancerdoc89 Knowledge is Power

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    Which of the following properties of the red blood cell allows it to complete its course through the circulation?

    a. lack of a nucleus
    b. lack of protein production
    c. lack of a structural protein network
    d. lack of cholesterol in the cell membrane

    ...I'm down to two possible answers and can support both of them...which answer would you choose and why??
     
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  3. vayntraubinator

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    Lack of protein structural network so that it can make it through the small width of the capillaries.
     
  4. HelloNicky

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    #3 HelloNicky, Aug 1, 2011
    Last edited: Aug 1, 2011
  5. vnicolas

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  6. dancerdoc89

    dancerdoc89 Knowledge is Power

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    Thanks for your answers/references....the apparent answer is A...the exact two that I chose were A and C for the reasons you guys mentioned. I swear this is the case for the many practice MCAT questions that I've gone through in BS sections...ugh! :mad:

    btw, this question is from Kaplan...dunno if that carries any rhyme or reason for the uncertainties :thumbdown:
     
  7. kkentm

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    does a red blood cell actually lack a protein network? wouldnt that result in a cell being of no consistent shape since there is no structural support? i figure since red blood cells have a consistent biconcave shape they must have some type of structurally supporting mechanism
     
  8. dancerdoc89

    dancerdoc89 Knowledge is Power

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    Ok, I would think it must have some sort of structural network...however I would think that network would have to be established before the nucleus disappears...you need the DNA to transcribe/translate proteins that the cell needs. So, I think saying that a RBC lacks a protein network is pushing it.

    However, I recall that not having such a prominent protein network (i.e. microfilaments) give the RBC flexibility so it can fit through capillaries (as someone else mentioned before)
     
  9. kkentm

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    ^ can you post Kaplan's answer explanation for us? that would be nice
     
  10. dancerdoc89

    dancerdoc89 Knowledge is Power

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    I would if I could...I actually copied the letter answers only b/c this particular practice test expired, so I cannot access it online anymore. I have the questions/passages/letter answers copied (more like print-screened) but not the explanations.

    I know, it does us no good. My apologies!

    Even so, I wanted to see how people have different instincts (and support) about answering a given MCAT question...and this was one of them.
     
  11. TieuBachHo

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    The answer is A:

    The red blood cells actually has structural protein network embedded in its membrane. It helps to maintain its structural integrity, elasticity, and also to prevent premature-SELECTIVE senescence.
     
  12. whiteshadodw

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    i agree. B and C basically say the same thing, while D doesn't exactly make sense. cholesterol makes things more flexible, not less.
     
  13. AlphaMagnum

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    Cholesterol makes things less flexible? In my Biochem and Molecular Biology courses, I was taught that cholesterol, when inserted into cellular membranes, makes them more rigid...
     
  14. whiteshadodw

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    you must have learned wrong and read what i wrote wrong. cholesterol interacts with fatty acids so they are less likely to freezing. the fatty acids are not as prone to becoming crystalline with higher cholesterol levels.

    from wiki:
    "Cholesterol is required to build and maintain membranes; it modulates membrane fluidity over the range of physiological temperatures."
     
  15. salim271

    salim271 Patience is tough. :/
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    ^This is right, cholesterol acts in a similar way that a double bond in a fatty acid would, it causes kinks and therefore reduces the amount of stacking and londons interactions the membrane FAs can do, increasing fluidity.
     

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