The following is a portion of an mRNA sequence: 3'-AUCGUCAUGCAGA-5' Write out the sequence and polarity of the DNA duplex that encodes this mRNA segment. Label the template and coding DNA strands.

Key Concepts

Transcription

Transcription is the process by which the genetic information in DNA is copied into messenger RNA (mRNA). During this process, RNA polymerase synthesizes mRNA from the DNA template strand, using complementary base pairing. The mRNA sequence is synthesized in the 5' to 3' direction, which is crucial for understanding how the corresponding DNA strands relate to the mRNA.

DNA Strands

DNA consists of two strands: the coding (or sense) strand and the template (or antisense) strand. The coding strand has the same sequence as the mRNA (except for thymine (T) being replaced by uracil (U) in RNA), while the template strand is complementary to the mRNA. Understanding the roles of these strands is essential for determining the correct DNA sequence that encodes a given mRNA.

Polarity

Polarity in nucleic acids refers to the directionality of the strands, which is indicated by the 5' and 3' ends. The 5' end has a phosphate group, while the 3' end has a hydroxyl group. This polarity is important for both the synthesis of mRNA during transcription and for the complementary base pairing between DNA and RNA, as well as for understanding the orientation of the DNA strands in relation to the mRNA sequence.