Question

If you have a strand of DNA that reads 3'TACGCGATAGGCAAATT5'. 1. Give the corresponding strand of mRNA 2. Assuming the last condon is a stop codon, will this mRNA strand code correctly for a five amino acid protein

Answer 1

5'AUGCGCUAUCCGUUUAA3'

No, the mRNA strand code will not have a five amino acid protein.

1 Explanation:

Use this formula and it can not be the other way around unless stated:

T translates to A

A translates to U

G translates to C

C translates to G

Because the congruent strand is reciprocal to the mRNA strand, the original 3' - 5' would need to be flipped to 5' - 3'

Thus the answer for 1. is 5'AUGCGCUAUCCGUUUAA3'

2. Explanation:

Let's break the sequence into codons.

AUG - CGC - UAU - CCG - UUU - AA

AUG states for the start point so it doesn't count as a five amino acid protein, thus eliminating it.

CGC - UAU - CCG - UUU - AA

As stated in the question, the last codon is the stop codon, thus eliminating that as well.

CGC - UAU - CCG - UUU

Now the remaining codon would be only 4, not five thus it wouldn't have five amino acid proteins.

Hope this helps!

Answer 2

1. 5'AUGCGCUAUCCGUUUAA3'

2. No

Step-by-step explanation:

1. Considering the base-pairing rule, the substitution of the thymine base in DNA with Uracil base in the corresponding mRNA, and the directionality in DNA/RNA; the corresponding mRNA sequence from the DNA strand 3'TACGCGATAGGCAAATT5' would be: 5'AUGCGCUAUCCGUUUAA3'

2. A codon is made up of 3 nucleotide bases. There are 17 nucleotide bases in the mRNA and if the last codon is a stop codon, it means 14 nucleotide bases would be translated. When 14 is divided by 3, there would be 4 complete codons and 2 nucleotide bases would remain. Hence, the mRNA cannot code correctly for a five amino acid protein.