GRE Biology Test Question

Discussion in 'Science' started by ryobi, Mar 1, 2020.

  1. ryobi

    ryobi Well-Known Member

    Joined:
    Sep 28, 2013
    Messages:
    2,797
    Likes Received:
    218
    Trophy Points:
    63
    Gender:
    Male
    What is the complementary DNA sequence to this strand of DNA???

    5' CGA TTG 3'
     
  2. Burzmali

    Burzmali Well-Known Member Past Donor

    Joined:
    Sep 24, 2009
    Messages:
    4,315
    Likes Received:
    348
    Trophy Points:
    83
    Seriously? 3' GCT AAC 5'
     
  3. ryobi

    ryobi Well-Known Member

    Joined:
    Sep 28, 2013
    Messages:
    2,797
    Likes Received:
    218
    Trophy Points:
    63
    Gender:
    Male
    See, that's what I thought but the test booklet is saying the correct answer is

    5' CAA TCG 3'

    ???
     
    Last edited: Mar 3, 2020
  4. ryobi

    ryobi Well-Known Member

    Joined:
    Sep 28, 2013
    Messages:
    2,797
    Likes Received:
    218
    Trophy Points:
    63
    Gender:
    Male
    I didn't think DNA was read in the 5' to 3' direction either only the 3' to 5' direction even on the daughter strand because DNA polymerase requires a free 3' OH group for the initiation of synthesis, ergo it can synthesize DNA in only one direction the 3' to 5' direction but the answer in the test booklet is intimating that the DNA on the daughter strand is formed in the 5' to 3' direction???
     
    Last edited: Mar 3, 2020
  5. Burzmali

    Burzmali Well-Known Member Past Donor

    Joined:
    Sep 24, 2009
    Messages:
    4,315
    Likes Received:
    348
    Trophy Points:
    83
    Ah, okay. They were looking for the build direction, not simply the paired sequence. Yeah, DNA pol has to add onto the 3' side, so reading the build sequence from left to right would be 5' CAA TCG 3'. I thought it sounded like a simple question. I guess that detail is what makes it GRE-level.
     
  6. ryobi

    ryobi Well-Known Member

    Joined:
    Sep 28, 2013
    Messages:
    2,797
    Likes Received:
    218
    Trophy Points:
    63
    Gender:
    Male
    The polymerase binds to the OH group on the 3' prime end of the antisense strand but nucleotides are added in the 5' to 3' direction on the new strand therefore the new strand is read in the 5' to 3' direction???
     
    Last edited: Mar 4, 2020

Share This Page