Chem/Bio HW question... Need help...

[EternityOfPain]

I am having trouble answering the following question any help would be greatly apperciated.

1. A protein must be synthesized by a cell. Part of the amino acid sequence in this protein is:


-Ala-Gly-Thr-Leu-

The codons for these amino acids are:
Gly -- G G C
Leu -- C U A
Thr -- U A U
Ala -- G C A

Write the base sequence for the complete chain as given and the complimentary bases as would be found in the DNA from which it was taken.

I am completely confused on how to appoarch this problem...

It said the whole sequence however only part is given. So what I am assumping it is G C A G G C U A U C U A? But as far as complimentary bases I am at a lost. Any help would be great. Thanks.

[graymouser]

Sorry I didn't see this question earlier. I warn you it's been a long time since I've taken genetics, so I make no guarantees.

Since they say the entire sequence "as given" I assume the question means just the part you are given.

The part that confuses me is the reference to the codon. I thought that the codon referred to the mRNA and the anticodon to the tRNA. It looks like they skipped a part of the transcription process. Shouldn't it be DNA to mRNA to tRNA to amino acid sequence? It seems like they are missing the tRNA step.

Anyways, taking the question at face value, the codons on the mRNA should indeed read GCA GGC UAU CUA. Since the master code is on the DNA, the complimentary bases on the side of the DNA that was directly copied would be CGT CCG ATA GAT. (T replaces U when you switch between RNA and DNA)

The entire strand of DNA code would be
CGT CCG ATA GAT
GCA GGC TAT CTA

As I said before though. The question seems to skip the anticodon step. I'm not sure if this is accidental or not. If they really meant that the tRNA anticodon was GCA GGC UAU CUA then the answer is different.

[EternityOfPain]

Thanks for your help! These were some practice problems for my final tomorrow. After tomorrow I am school free to end of Jan!