Q 27E - Organic Chemistry (Mcmurry)

Question

Question: From what DNA sequences were each of the mRNA codons in problem 28-26 transcribed?

1. AAU
2. GAG
3. UCC
4. CAU

Step-by-Step Solution

Answer

mRNA molecules are made by transcribing from the antisense strand of DNA. The sequence is complementary to the mRNA and will contain thymine instead of uracil.

1. $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{A}-\mathrm{A}-\mathrm{U}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{T}-\mathrm{T}-\mathrm{A}-5\text{'} \end{gathered}$$
   
2. $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{G}-\mathrm{A}-\mathrm{G}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{C}-\mathrm{T}-\mathrm{C}-5\text{'} \end{gathered}$$
   
3. $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{U}-\mathrm{C}-\mathrm{C}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{A}-\mathrm{G}-\mathrm{G}-5\text{'} \end{gathered}$$
   
4. $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{C}-\mathrm{A}-\mathrm{U}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{G}-\mathrm{T}-\mathrm{A}-5\text{'} \end{gathered}$$
   

Step 1: Definition of DNA sequence

Determining the order of the four chemical building blocks called "bases" which make up the DNA molecule is defined as DNA sequence.

Step 2: Explanations

1. mRNA molecules are made by transcribing from the antisense strand of DNA. The sequence is complementary to the mRNA and will contain thymine instead of uracil.      $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{A}-\mathrm{A}-\mathrm{U}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{T}-\mathrm{T}-\mathrm{A}-5\text{'} \end{gathered}$$
2. mRNA molecules are made by transcribing from the antisense strand of DNA. The sequence is complementary to the mRNA and will contain thymine instead of uracil.     $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{G}-\mathrm{A}-\mathrm{G}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{C}-\mathrm{T}-\mathrm{C}-5\text{'} \end{gathered}$$
3.  mRNA molecules are made by transcribing from the antisense strand of DNA. The sequence is complementary to the mRNA and will contain thymine instead of uracil.     $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{U}-\mathrm{C}-\mathrm{C}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{A}-\mathrm{G}-\mathrm{G}-5\text{'} \end{gathered}$$
4. mRNA molecules are made by transcribing from the antisense strand of DNA. The sequence is complementary to the mRNA and will contain thymine instead of uracil.     $$\begin{gathered} \mathrm{mRNA} 5\text{'}-\mathrm{C}-\mathrm{A}-\mathrm{U}-3\text{'} \\ \mathrm{antidense} \mathrm{DNA} 3\text{'}-\mathrm{G}-\mathrm{T}-\mathrm{A}-5\text{'} \end{gathered}$$