I'm a bit confused about genes
Biology discussion, revision, exam and homework help.
-
- Reputation:
- Thread Starter
- Junior Member
- Posts: 40
I'm a bit confused about genesI'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
-
- Reputation:
- Banned
- Posts: 456
- Warning points: 15
Re: I'm a bit confused about geneshttp://en.wikipedia.org/wiki/Gene
curtsy of Wikipedia -
- Reputation:
- Exalted and Worshipped Member
- Posts: 1,384
Re: I'm a bit confused about genesAt A level you can get away with saying either....I think(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
-
- Reputation:
- TSR Legend
- Location: London
- Posts: 10,877
Re: I'm a bit confused about genesI 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.(Original post by The Illuminati)
At A level you can get away with saying either....I think
Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't...
-
- Reputation:
- PS Helper
- TSR Royalty
- Location: Bristol
- Posts: 20,660
Re: I'm a bit confused about genesAQA 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!)(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.
Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't...
-
- Reputation:
- Exalted and Worshipped Member
- Posts: 1,384
Re: I'm a bit confused about genes(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.
Personally, I would interpret 'a' and 'one' as one and the same thing, but AQA apparently don't...
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)
Last edited by The Illuminati; 15-05-2012 at 21:28. -
- Reputation:
- Peer Of The TSR Realm
- Posts: 1,790
Re: I'm a bit confused about geneshahaha.(Original post by Blackburn_Allen)
Levi's are the best. -
- Reputation:
- TSR Legend
- Location: London
- Posts: 10,877
Re: I'm a bit confused about genes
Don't worry - no exam board is as bad as AQA...(Original post by The Illuminati)
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)
Shame that DNA helicase / polymerase don't work on them - can't replicate the genes and make a fortune(Original post by Blackburn_Allen)
Levi's are the best.
Last edited by thegodofgod; 15-05-2012 at 21:22. -
- Reputation:
- PS Helper
- Respected Member
- Posts: 156
Re: I'm a bit confused about genesReally? 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?(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. -
- Reputation:
- Adored and Respected Member
- Location: Somerset
- Posts: 530
Re: I'm a bit confused about genesSorry! Yes you're right, I meant 2 genes code for it!(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?
(unless OCR are that cruel too, which tbh they probably are)
