transcription question

[jeezy]

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3 anticodons of GAU tranlate mRNA, find the DNA

3 anticodons would line up GAU GAU GAU
making the mRNA 5' CUA CUA CUA 3'
which is copied antiparallel or whatever, so wouldnt the DNA be 5' TAG TAG TAG 3'

GAT GAT GAT was the only choice and the ends weren't labeled, so i got it right... but am i overthinking this, or if the ends were labeled would i be right?

 

[jeezy]

anyone

 

[dentgirl08]

mRNA 5' CUA CUA CUA 3'
then isn't the corresponding DNA 3' GAT GAT GAT 5' ?
i think you just need to the flip the 3' to match the 5' no?

 

[Dotoday]

Yes you are right, it would be the same thing if the ends were labeled because the anticodon sequence is the same. If in the original problem the ends are not labeled then don`t worry about it.
This is the only choice that makes sence. This is correct, because you need to match the anticodon of the tRNA with the complement sequence of mRNA. Then you match mRNA sequence to that of DNA. You got the right answer.

 

[Dental Guy]

Anticodons and DNA code the same. You just replace the U from the Anticodon with T in DNA. Easy.

 

[tresbon]

3 anticodons of GAU tranlate mRNA, find the DNA

3 anticodons would line up GAU GAU GAU
making the mRNA 5' CUA CUA CUA 3'
which is copied antiparallel or whatever, so wouldnt the DNA be 5' TAG TAG TAG 3'

GAT GAT GAT was the only choice and the ends weren't labeled, so i got it right... but am i overthinking this, or if the ends were labeled would i be right?

DNA or RNA polymerases can only add nucleotides to the 3' end of the growing polymer. So, it's understood that mRNA will elongate in the 5' ----> 3' direction, which is what you got here, 5' CUA CUA CUA 3'.

If you notice that carefully, transcription is actually some kind of snapshot on DNA replication, where the template strand of DNA will have to be transcribed complementarily from 3' ----> 5'. Hence, 3' GAT GAT GAT 5' on the DNA.

I bet these are just implied conventions adopted by Achiever when getting this question set up. That’s why you don’t see the answers labeled.

 

[Sillygirl]

I think the tricky part is that you have to assume that the rRNA
GAU GAU GAU is already in the 5'-3' direction. Then you work backwards and think mRNA would be in the 3'-5' direction to give you 3'-CUA CUA CUA-5' and then to get to DNA you just work backwards again to give 5'-GAT GAT GAT-3'

yea?? hehe