If the sequence of a section of DNA is 5’-TACGGACTCTTATCGACT-3’ a)what is the correct sequence for the opposite strand? b)Using that RNA strand, what is the amino acid sequence it would make?

Answer 1

Hey! So, when looking at a problem like this, we have to consider the central dogma of protein synthesis, that is:

DNA --transcription--> RNA ----translation---> PROTEIN

We understand that first, we must transcribe our DNA section into an mRNA molecule, and from there we can translate each bit of our mRNA molecule into a different amino acid (the building blocks of proteins).

That being said, we can tackle your problem.

First, for part A, we have to remember our essential DNA/RNA base pairs:

A:U

G:C

If I understand correctly, the question is asking you to provide the complementary RNA strand that pairs with your DNA sequence.

Following our base-pair rules above, when transcribing this DNA sequence to mRNA, the complementary RNA strand should read:

AUGCCUGAGAAUAGCUGA

Our transcription is complete! From here, the next step is to translate our mRNA into its corresponding amino acids. To do this, we must first separate our bases into translatable groups of three, called codons.

AUG - CCU - GAG - AAU- AGC - UGA

We can then use a codon chart to match our codons to corresponding amino acids.

We follow a pattern of choosing the first, second and third letter of each codon, and narrow it down to a single amino acid per codon. Following these rules, we should end up with an amino acid change that looks like this:

Met - Pro - Glu - Asn - Ser - STOP

(**Note: Notice that our first codon was translated to Met, which is labeled as a START codon, and our last codon didn't have a corresponding amino acid, it instead had the word STOP. We call the sequence "AUG" -~ which codes for the amino acid Met ~ a start codon, because it actually notifies our cell that this is where we must begin translation. You will almost always see Met at the beginning of your amino acid sequence in problems like this. conversely, the base pair codon "UGA" is one of three stop codons, which notify the cell to stop translation. These codons don't result in amino acids, and as a result we simply write "STOP" in our amino acid chain.)

I hope this helped! Please let me know if there's anything else I can do. :)