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Homework Help: (bio) DNA Question

  1. Oct 19, 2009 #1
    1. The problem statement, all variables and given/known data

    Which of the following are true statements ?

    a) DNA is composed of a series of necleotides, each of which is made up of a phosphoric acid unit, a sugar unit and a cyclic nitrogen base.

    b) In DNA the base must be either alanine, threonine, glutamine, or cysteine.

    c) In the three-dimensional Watson-Crick structure of DNA, two polynucleotide DNA strands wind around each other to form a double helix.

    d) The DNA sequence of base pairs in the nucleus of a cell represents the genetic code that controls inherited characteristics.

    e) Genes are the sequence of bases in DNA that are the code for the synthesis of a single protein within the body.

    2. The attempt at a solution

    a) [FALSE]It can not be a because it should be phosphate group instead of cyclic nitrogen base
    b) [TRUE?] I thought it should be correct, since DNA bases are adenine (A), guanine (G), thymine (T), and cytosine (C)
    c) [TRUE] It's true that the two polynucleotide chains in DNA molecule.
    d) [TRUE] the bases are unique, that tells the characteristics
    e) [FALSE?] I'm not sure, but I thought that it should be since genes are code for synthesis of proteins.

    I tried bcde and bcd but it's incorrect. :( Please help, thank you!
  2. jcsd
  3. Oct 19, 2009 #2
    Whats the question?
  4. Oct 19, 2009 #3
    Wait are you saying that you thought that your answers were correct but they were wrong? bcd right?

    B- It is False. Read what you wrote and re-read the question. Alanine... do you even know what this is anyways? (Hint it's not what you SAID was a base for DNA... so you know the bases properly but the question doesn't contain any of those...)

    c- It is also false... Again you have to read the wording very carefully. Is each individual strand a polynucleotide or just a simple nucleotide.

    d- I would say this one is also false. I'm pretty sure it's the Genes which are part of the genotype that contain this information. Not all the sections of DNA are used for coding. Parts of a Gene may also not be used for coding protein but they control when the charateristic is active.

    It appears to me that you do know your stuff you just need to re-read the question more thoroughly so that you can better understand them and give a more accurate answer. Just because you know what is going on doesn't mean it is relevant to the question.
    Last edited: Oct 19, 2009
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