What mRNA base sequences are complementary to the following DNA template sequences? Be sure to label the 5′ and 3′ ends of the complementary sequences.


a. 5′ CAT GCT CTA CAG 3′

Verified step by step guidance

1. Identify the direction of the given DNA template sequence. The sequence provided is 5′ to 3′, which means it is the coding strand.
2. Recall that mRNA is synthesized in the 5′ to 3′ direction, complementary to the DNA template strand, which is read in the 3′ to 5′ direction.
3. Determine the complementary RNA bases for each DNA base: Adenine (A) pairs with Uracil (U), Thymine (T) pairs with Adenine (A), Cytosine (C) pairs with Guanine (G), and Guanine (G) pairs with Cytosine (C).
4. Write the complementary mRNA sequence by replacing each DNA base with its RNA complement, starting from the 3′ end of the DNA template to the 5′ end.
5. Label the ends of the mRNA sequence, ensuring the 5′ and 3′ ends are correctly indicated.

Key Concepts

DNA and RNA Structure

DNA and RNA are nucleic acids composed of nucleotide sequences. DNA is double-stranded and contains the bases adenine (A), thymine (T), cytosine (C), and guanine (G). In contrast, RNA is typically single-stranded and contains uracil (U) instead of thymine. Understanding the structural differences is crucial for determining how base pairing occurs during transcription.

Base Pairing Rules

Base pairing rules dictate how nucleotides pair with each other. In DNA, adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G). During transcription, the complementary RNA sequence is formed by pairing adenine with uracil (A-U) and cytosine with guanine (C-G). Knowing these rules is essential for accurately determining the mRNA sequence from a given DNA template.

5′ and 3′ Ends

The 5′ and 3′ ends of nucleic acid strands refer to the orientation of the sugar-phosphate backbone. The 5′ end has a phosphate group attached, while the 3′ end has a hydroxyl group. This directional notation is important in molecular biology, as it affects how nucleic acids are synthesized and how they interact during processes like transcription and translation.