To determine the sequence of nucleotides in the template strand of DNA that could code for the polypeptide sequence Val-Asp-Ser, we need to follow these steps:
1. Identify the mRNA codons for each amino acid:
- Valine (Val) is encoded by GUU, GUC, GUA, or GUG.
- Aspartic acid (Asp) is encoded by GAU or GAC.
- Serine (Ser) is encoded by UCU, UCC, UCA, UCG, AGU, or AGC.
Let’s use GUU for Valine, GAU for Aspartic acid, and UCU for Serine. Therefore, the mRNA sequence for Val-Asp-Ser is:
[tex]\[ \text{GUU-GAU-UCU} \][/tex]
2. Determine the complementary DNA sequence:
- RNA has the bases A, U, G, and C.
- DNA has the complementary bases T, A, C, and G.
To find the DNA template strand, we will use the complementary pairing rule:
- G (in RNA) pairs with C (in DNA)
- U (in RNA) pairs with A (in DNA)
- A (in RNA) pairs with T (in DNA)
- C (in RNA) pairs with G (in DNA)
Thus, the complement of the mRNA sequence GUU-GAU-UCU is:
[tex]\[ \text{CAACTAAGA} \][/tex]
3. Verify the result:
- From the provided sequence:
- G (RNA) [tex]\(\rightarrow\)[/tex] C (DNA)
- U (RNA) [tex]\(\rightarrow\)[/tex] A (DNA)
- U (RNA) [tex]\(\rightarrow\)[/tex] A (DNA)
- Repeating the process for each codon:
- GUU [tex]\(\rightarrow\)[/tex] CAA
- GAU [tex]\(\rightarrow\)[/tex] CTA
- UCU [tex]\(\rightarrow\)[/tex] AGA
So, the complete sequence of nucleotides in the template strand of DNA that codes for the polypeptide sequence Val-Asp-Ser is:
[tex]\[ \text{CAACTAAGA} \][/tex]
Hence, the template strand of DNA that could code for the polypeptide sequence Val-Asp-Ser is [tex]\( \text{CAACTAAGA} \)[/tex].
