The amino acid serine is coded by the mRNA codon AGU. What is the base sequence of the DNA gene that originally produced this mRNA codon?
The mRNA codon AGU corresponds to the DNA codon UCA.
In DNA, the base adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Therefore, the DNA codon UCA can be determined by replacing the uracil (U) in the mRNA codon AGU with its corresponding base, which is adenine (A).
Thus, the base sequence of the DNA gene that originally produced the mRNA codon AGU would be TCA.
To determine the base sequence of the DNA gene that produced the mRNA codon AGU, we can use the process of transcription and reverse complementation.
First, it's important to know that during transcription, the mRNA molecule is synthesized using a DNA template strand, where the RNA bases pair with their complementary bases on the DNA template.
The mRNA codon AGU corresponds to the amino acid serine (Ser). To find the DNA gene sequence, we need to determine the reverse complement of AGU.
Step 1: Find the reverse complement of AGU
The reverse complement of AGU is UCA.
Step 2: Convert RNA bases to their DNA counterparts
In DNA, the base U (uracil) is replaced by T (thymine). Therefore, UCA in RNA becomes TCA in DNA.
So, the base sequence of the DNA gene that originally produced the mRNA codon AGU is TCA.
To determine the base sequence of the DNA gene that produced the mRNA codon, we can use the process of transcription and the genetic code.
1. Identify the mRNA codon: The given mRNA codon is AGU, which codes for the amino acid serine.
2. Determine the DNA codon: To find the corresponding DNA codon, we need to use the known pairing of bases between DNA and RNA. In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). In RNA, uracil (U) replaces thymine (T).
Since the mRNA codon is AGU, we can replace U with T to obtain the DNA codon. Therefore, the DNA codon corresponding to AGU is AGT.
3. Reverse the DNA codon: Since DNA is read in a different direction during transcription, we need to reverse the DNA codon.
Reversing AGT gives TGA, which is the base sequence of the DNA gene that originally produced the mRNA codon AGU.
So, the base sequence of the DNA gene is TGA.