1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Double-stranded DNA molecule is 22% cytosine

  1. Nov 20, 2008 #1
    i am stuck on this problem and was hoping someone could help..

    If a double-stranded DNA molecule is 22% cytosine, what are the percentages of guanine, adenine, and thymine?

    Thanks
     
  2. jcsd
  3. Nov 20, 2008 #2

    Borek

    User Avatar

    Staff: Mentor

    Re: chem

    Hint: there will be the same amount of one of the other three.
     
  4. Nov 20, 2008 #3
    Re: chem

    thanks, so 26% each
     
  5. Nov 20, 2008 #4

    Borek

    User Avatar

    Staff: Mentor

    Re: chem

    Which each, and why 26%?
     
  6. Nov 20, 2008 #5
    Re: chem

    if 22% is is cytosine, i subtract 22 from 100 and get 78, then i divided that by 3 which is 26
    so there is 26%, guanine, 26% adenine, and 26% thymine..

    Right??
     
  7. Nov 21, 2008 #6

    Borek

    User Avatar

    Staff: Mentor

    Re: chem

    No, there must be other base that is present in exactly 22% quantity. Do you know how they pair?
     
  8. Nov 21, 2008 #7
    Re: chem

    T & A pair and C & G pair..
    so what are the steps i need to take?
     
  9. Nov 21, 2008 #8

    Borek

    User Avatar

    Staff: Mentor

    Re: chem

    Thinking will be enough. If there is 22% of C, how much G do you expect?
     
  10. Nov 21, 2008 #9
    Re: chem

    So the hint u gave me was that there will be the same amount of one of the other three.
    Then u said there must be other base that is present in exactly 22% quantity...

    im soo lost please help!!
     
  11. Nov 21, 2008 #10

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    Re: chem

    If C pairs with G then there must be equal amounts of each assuming this is good DNA. Draw pictures if it helps.
     
  12. Nov 22, 2008 #11

    Borek

    User Avatar

    Staff: Mentor

    Re: chem

    Perhaps my English fails me, but from what I understand you have stated twice exactly the same.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?