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EK Biology Book > Typos

Discussion in 'MCAT Study Question Q&A' started by futuredoctor10, Dec 31, 2008.

  1. futuredoctor10

    Verified Account 10+ Year Member

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    EK: Gram-positive bacteria... "The space between the plasma membrane and the cell wall is called the periplasmic space" (p. 65)

    Error: The periplasmic space is unique to gram negative organisms.

    EK: "Genes located close together on a chromosome are more likely to cross over together, and are said to be linked" (p. 49)

    Error: I am not sure but think this is wrong. Genes located further apart are more likely to undergo genetic recombination/crossing over.
     
  2. Airplay355

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    I think the second part means genes close together are more likely to cross over together, not more likely to have a cross between them. So the two genes would move together because of their close proximity.
     
  3. G1SG2

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    You're correct.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  4. cyclin M

    cyclin M megaman
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    hmm I might be wrong, but I think this is not a typo and what EK has written is correct.

    Genes closer together are linked because when crossing over occurs both are more likely to cross over together.

    However what you said is true as well.

    So what you said is basically like:

    EK: the sky is blue
    You: no, the sky is not red

    Both are true. Just recognize that CROSSING OVER (recombination) and CROSSING OVER TOGETHER (linked) are not the same thing.

    Here's a good explanation by someone else:

     
  5. OP
    OP
    futuredoctor10

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    Yeah the second statement is not a typo. I saw Toomuchresearch's diagrams in another thread after posting this, and they help clarify everything.

    Yeah keeping this in mind helps- crossing over together (linked) on the same chromosome vs. crossing over 2 genes on diff chromosomes/recombination
     

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