Hey there Sign in to join this conversationNew here? Join for free

I'm a bit confused about genes

Announcements Posted on
Study Help needs new mods! 14-04-2014
Post on TSR and win a prize! Find out more... 10-04-2014
    • Thread Starter
    • 0 followers
    Offline

    ReputationRep:
    I'm just wondering: if a protein has a quaternary structure, are all the polypeptide chains that it consists of coded for by a single gene? All of my AS bio textbooks define a gene as the code for a polypeptide. However, a protein such as haemoglobin consists of more than one polypeptide chain. Would I be wrong to say in an exam that a gene codes for a protein rather than a single polypeptide?

    Thank you
    • 5 followers
    Offline

    ReputationRep:
    http://en.wikipedia.org/wiki/Gene

    curtsy of Wikipedia
    • 1 follower
    Offline

    ReputationRep:
    Technically yes, but I'm not sure if they would penalise it. 2 genes code for haemoglobin, and are both adjacent to each other on DNA.
    • 5 followers
    Offline

    ReputationRep:
    (Original post by Ggdf)
    I'm just wondering: if a protein has a quaternary structure, are all the polypeptide chains that it consists of coded for by a single gene? All of my AS bio textbooks define a gene as the code for a polypeptide. However, a protein such as haemoglobin consists of more than one polypeptide chain. Would I be wrong to say in an exam that a gene codes for a protein rather than a single polypeptide?

    Thank you
    At A level you can get away with saying either....I think
    • 25 followers
    Offline

    ReputationRep:
    (Original post by The Illuminati)
    At A level you can get away with saying either....I think
    I asked my teacher (who's also the head of biology at my school) about this exact question, and she e-mailed AQA for clarification - the reply was, that if you define a gene as 'A length of DNA that codes for a polypeptide', you'll get the mark, however, if you define a gene as 'A length of DNA that codes for one polypeptide', you won't get the mark. :lolwut:

    Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't... :wtf:
    • 10 followers
    Offline

    ReputationRep:
    (Original post by thegodofgod)
    I asked my teacher (who's also the head of biology at my school) about this exact question, and she e-mailed AQA for clarification - the reply was, that if you define a gene as 'A length of DNA that codes for a polypeptide', you'll get the mark, however, if you define a gene as 'A length of DNA that codes for one polypeptide', you won't get the mark. :lolwut:

    Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't... :wtf:
    AQA are talking rubbish... obviously their opinion matters, since they're the ones writing the mark scheme, but that doesn't make any sense, and would be wrong even if it were... (Besides which, a gene can code for several polypeptides on the basis of alternative splicing!)
    • 5 followers
    Offline

    ReputationRep:
    (Original post by thegodofgod)
    I asked my teacher (who's also the head of biology at my school) about this exact question, and she e-mailed AQA for clarification - the reply was, that if you define a gene as 'A length of DNA that codes for a polypeptide', you'll get the mark, however, if you define a gene as 'A length of DNA that codes for one polypeptide', you won't get the mark. :lolwut:

    Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't... :wtf:
    :unimpressed: WTF, last time I checked a and one were practically interchangeable, that's ridiculous. I guess it's a good thing that I never say one and always say a....it's even better that I don't do AQA (unless OCR are that cruel too, which tbh they probably are)
    • 2 followers
    Offline

    ReputationRep:
    Levi's are the best.
    • 2 followers
    Offline

    ReputationRep:
    (Original post by Blackburn_Allen)
    Levi's are the best.
    hahaha.
    • 25 followers
    Offline

    ReputationRep:
    (Original post by Cirsium)
    AQA are talking rubbish...
    :yy:

    (Original post by The Illuminati)
    :unimpressed: WTF, last time I checked a and one were practically interchangeable, that's ridiculous. I guess it's a good think that I never say one and always say a....it's even better that I don't do AQA (unless OCR are that cruel too, which tbh they probably are)
    Don't worry - no exam board is as bad as AQA... :moon:

    (Original post by Blackburn_Allen)
    Levi's are the best.
    Shame that DNA helicase / polymerase don't work on them - can't replicate the genes and make a fortune :ahee:
    • 1 follower
    Offline

    ReputationRep:
    (Original post by dmccririck)
    Technically yes, but I'm not sure if they would penalise it. 4 genes code for haemoglobin, and are all adjacent to each other on DNA.
    Really? I thought that haemoglobin had 2 identical alpha subunits and 2 identical beta subunits? Is it not a waste of coding region to have 4 genes next to each other?
    • 1 follower
    Offline

    ReputationRep:
    (Original post by qiaoyu.he)
    Really? I thought that haemoglobin had 2 identical alpha subunits and 2 identical beta subunits? Is it not a waste of coding region to have 4 genes next to each other?
    Sorry! Yes you're right, I meant 2 genes code for it!

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?

    this is what you'll be called on TSR

  2. this can't be left blank
    this email is already registered. Forgotten your password?

    never shared and never spammed

  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By completing the slider below you agree to The Student Room's terms & conditions and site rules

  2. Slide the button to the right to create your account

    Slide to join now Processing…

    You don't slide that way? No problem.

Updated: May 15, 2012
Article updates
Reputation gems:
You get these gems as you gain rep from other members for making good contributions and giving helpful advice.