Remember that DNA polymerase builds the new strand by reading the original DNA strand in a 3' to 5' direction. The newly formed strand will be read 5' to 3' and will have nucleotides that are complementary to the original strand.

During transcription, a complimentary RNA strand is constructed from a DNA template. It is important to realize that in RNA, the nucleotide base uracil is used instead of thymine as a complementary pair with adenine. The complementary strand is constructed 5’ to 3’ , but is lined up anti-parallel to the original strand.

When transcribing from a template strand, here are a few things to remember:

1. RNA polymerase reads the strand in the 3' to 5' direction.

2. In the RNA transcript, thymine is replaced with uracil.

In order to double check, make sure that the two strands are complementary when antiparallel to one another.

Template: 5'-ACTTGCAGGCC-3'

Transcript: 3'-UGAACGUCCGG-5'

mRNA is transcribed antiparallel to the DNA template, meaning that the 5' end of the mRNA sequence should align with the 3' end of the DNA sequence. Pairing rules dictate that cytosine will pair with guanine and adenine with uracil, rather than thymine. Using these conventions, we can decipher the mRNA sequence that correlates to the given DNA template.

DNA: 3' ACCTGTTAC 5'

RNA: 5' UGGACAAUG 3'

The correct answer is 3'-UCGACGGAA-5'.

In order to arrive at this answer, it is important to note that we are starting with DNA and finding the complementary mRNA. We must remember that there is no thymine in RNA; instead of thymine, RNA has uracil. The last thing to remember is that the mRNA strand will be anti-parallel, meaning that the 5' end of the DNA sequence must match up with the 3' end of the RNA sequence. Cytosine and guanine will form pairs. Adenine bases in DNA will pair to uracil bases in RNA, and thymine bases in DNA will bind to adenine in RNA.

DNA: 5'-AGCTGCCTT-3'

RNA: 3'-UCGACGGAA-5'

Both tRNA and DNA are complementary to mRNA, meaning that they will have the exact same sequence in the exact same direction with only one distinction: tRNA will use uracil where DNA uses thymine.

The given tRNA strand is 5'-AGUCGAUCUAGC-3'.

The corresponding DNA strand will be 5'-AGTCGATCTAGC-3'.

Nonsense mutations result in a premature stop codon, which would have resulted in a shorter peptide. A silent mutation means that there is a change in the nucleotide sequence, but not in the amino acid sequence. Thus, this is not likely the case seeing as there is a loss of function in the cloned and recombinantly expressed protein. We have no reason to believe that a frameshift mutation occurred. Rather, what the student observed was a point mutation that resulted in a missense reading of the gene.