Assume you have the DNA sequence 3'-ACGTATCCAGCAGCTCCACCAA-5'.
Use the genetic code table found in the chapter to answer the following questions:
a. What would the complementary DNA sequence be?
b. What would the corresponding mRNA sequence be?
c. Could the mRNA sequence you generated be translated? Why or why not?

Verified step by step guidance

1. To find the complementary DNA sequence, recall that DNA strands are antiparallel and complementary. Each base pairs with its complement: Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G). Since the given sequence is 3' to 5', the complementary strand will be 5' to 3'. Replace each base with its complement and reverse the direction accordingly.
2. To determine the corresponding mRNA sequence, remember that mRNA is synthesized from the DNA template strand by replacing Thymine (T) with Uracil (U). Use the complementary DNA strand as the template and transcribe it into mRNA by substituting each Thymine with Uracil, keeping the sequence in the 5' to 3' direction.
3. To assess if the mRNA sequence can be translated, check for the presence of a start codon (usually AUG) near the 5' end of the mRNA. Translation begins at the start codon, so if it is absent, the mRNA cannot be translated into a protein.
4. Also, consider if the mRNA sequence has a proper open reading frame (ORF) without premature stop codons. The ORF is a continuous stretch of codons starting with a start codon and ending with a stop codon, which is necessary for successful translation.
5. Summarize your findings by explaining whether the mRNA sequence contains the necessary signals (start codon and ORF) for translation and why this determines if the mRNA can be translated into a protein.

Key Concepts

DNA Complementary Base Pairing

DNA strands pair through specific base pairing rules: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). To find the complementary DNA strand, each base in the original strand is replaced by its partner, maintaining antiparallel orientation.

Transcription and mRNA Synthesis

During transcription, an mRNA strand is synthesized from the DNA template strand by replacing thymine (T) with uracil (U). The mRNA sequence is complementary to the DNA template and is written in the 5' to 3' direction, serving as a messenger for protein synthesis.

Translation and the Genetic Code

Translation is the process where ribosomes read mRNA codons to assemble amino acids into proteins. For translation to occur, the mRNA must have a start codon and be in the correct reading frame; otherwise, it cannot produce a functional protein.