A portion of the coding strand of DNA for a gene has the...

Question

A portion of the coding strand of DNA for a gene has the sequence
5′-...GGAGAGAATGAATCT...-3′

Assuming the mRNA is in the correct reading frame, write the amino acid sequence of the polypeptide using three-letter abbreviations and, separately, the amino acid sequence using one-letter abbreviations.

Accepted Answer

Hey, everyone. Let's take a look at this question together using the coding strand of DNA or gene with the sequence that runs in the 5 to 3 direction and contains the following nucleotides. Identify the amino acid sequence of the resulting polypeptide utilizing the three letter amino acid abbreviations. And you can see that we have four different answer choices, all containing different amino acid sequences. So we must transcribe our DNA sequence into the M R N A sequence. So we can determine the correct amino acid sequence. So starting off with the five end and breaking the strand into the nucleotide triplets, we have DC A followed by G A G followed by TT A and then C TT. And lastly, we have a G A and our three end which means that our complimentary M R N A strand starts with the three end is G G U followed by C U C. And then next, we have a A U and G A A. And lastly, we have U C U and our five N which we translated the coding strand of DNA into that M R N A sequence by using the complementary base pairs for each nucleotide. And so now that we have our M R A sequence, we can use the nucleotide triplets and our coding table to determine which amino acid each codon is coding for. So, starting off with G G U, we can see that G G U codes for glycine that we have G L Y as that three letter abbreviation for each amino acid. Next, we have C U C which we know C U C codes for lucine. So we have L EU. Then next, we have a A U which we conceive that A A U codes for asparagine. So we have a S N. And next, we have G A A which G A A codes for glutamic acid or G L U. And lastly, we have U C U which U C U codes for serene. We have S er which means that we have our amino acid sequence of G L Y followed by L eu, followed by A S N, followed by G L U. And lastly, we have S er which means that answer choice C is the correct amino acid sequence of the resulting polypeptide. Making answer choice C the correct answer. Since we have that coding strand of DNA, which we then convert to M R N A using the complementary base pairs for each nucleotide. And then we used our coding table to determine which amino acid each codon is coding for, to give us our amino acid sequence that utilizes the three letter amino acid abbreviations, which gives us the correct amino acid sequence found in answer choice C. So answer choice C is the correct answer. I hope you found this video to be helpful. Thank you and goodbye.

Key Concepts

Transcription

Translation

Amino Acid Codons

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