Question

The gene encoding the \(E\). coli enzyme enolase begins with the sequence ATGTCCAAAATCGTA. What is the sequence of the RNA transcript specified by this part of the gene?

Short answer

The RNA transcript is 5'-AUGUCCAAAAUCGUA-3'.

Step-by-step solution

Identify the DNA Template Strand

The given DNA sequence is 5'-ATGTCCAAAATCGTA-3'. To transcribe RNA, we need to consider the complementary strand, known as the template strand, which the RNA polymerase uses to build the RNA molecule. DNA is typically written as the coding strand, and RNA is synthesized complementary to the template strand. Thus, the template strand is 5'-TACAGGTTTTAGCAT-3'.

Transcribe the DNA Template to RNA

Replace each DNA base on the template strand with its complementary RNA base: - Adenine (A) pairs with Uracil (U) in RNA, - Thymine (T) pairs with Adenine (A), - Cytosine (C) pairs with Guanine (G), - Guanine (G) pairs with Cytosine (C). The template strand 5'-TACAGGTTTTAGCAT-3' transcribes to RNA as 5'-AUGUCCAAAAUCGUA-3'.

Write the RNA Sequence

The RNA sequence transcribed from the DNA template is 5'-AUGUCCAAAAUCGUA-3'. This sequence represents the strand of RNA that has been synthesized.

Key concepts

DNA Template Strand

In the process of RNA transcription, understanding the role of the DNA template strand is crucial. DNA is composed of two strands that run in opposite directions. However, for RNA synthesis, only one of these strands is used as a template. This strand is known as the DNA template strand.

The DNA template strand is complementary to the RNA strand that will be synthesized. During transcription, RNA polymerase "reads" this template strand and constructs the RNA molecule by following the complementary base pairing rules.

It is important to note that DNA sequences are generally given as the coding strand, which is not used directly in transcription. The coding strand has the same sequence as the RNA product (except that thymine in DNA is replaced by uracil in RNA). Therefore, the template strand is key to understanding how the RNA sequence is determined.

RNA Synthesis

RNA synthesis, also known as transcription, is the process by which RNA is created using a DNA template strand. This crucial biological process is carried out by the enzyme RNA polymerase.

RNA polymerase binds to the DNA at the promoter region, which signals the start of a gene. Once attached, it moves along the template strand, "reading" the DNA sequence. As it progresses, it synthesizes a complementary RNA strand.

This synthesis involves the formation of an RNA strand where each RNA nucleotide is added by pairing it with a complementary DNA base on the template strand. The result is a single-stranded RNA molecule that carries the genetic message required for protein synthesis.

RNA synthesis is an essential step in gene expression, serving as the intermediary between DNA, which holds the genetic code, and proteins, which perform most of the functions in a cell.

Complementary Base Pairing

Complementary base pairing is a fundamental principle in the process of DNA transcription and RNA synthesis. It ensures that the genetic code is precisely transferred from DNA to RNA.

In DNA, the bases adenine (A), thymine (T), cytosine (C), and guanine (G) pair specifically: A with T, and C with G. However, in RNA, thymine is replaced by uracil (U).

During transcription, complementary base pairing guides the assembly of the RNA strand:

• Adenine (A) on the DNA template pairs with uracil (U) on the RNA.
• Thymine (T) pairs with adenine (A).
• Cytosine (C) pairs with guanine (G).
• Guanine (G) pairs with cytosine (C).

This pairing is highly specific and critical for the accuracy of RNA transcription. It ensures that each RNA strand is a faithful copy of the gene's coding instructions as specified by the DNA.