Question

Write the segment of mRNA produced from the following section of a DNA template strand: \(-\mathrm{C}-\mathrm{C}-\mathrm{G}-\mathrm{A}-\mathrm{A}-\mathrm{G}-\mathrm{G}-\mathrm{T}-\mathrm{T}-\mathrm{C}-\mathrm{A}-\mathrm{C}-\)

Short answer

GGCUUCCAUG

Step-by-step solution

- Understand DNA to mRNA transcription

To transcribe DNA to mRNA, recognize that mRNA is complementary to the DNA template strand. The base pairs are as follows: Adenine (A) pairs with Uracil (U), Cytosine (C) pairs with Guanine (G), Guanine (G) pairs with Cytosine (C), and Thymine (T) pairs with Adenine (A).

- Identify each complementary mRNA base

Start with the first base of the DNA template and find its complementary mRNA base: - C (DNA) -> G (mRNA) - C (DNA) -> G (mRNA) - G (DNA) -> C (mRNA) - A (DNA) -> U (mRNA) - A (DNA) -> U (mRNA) - G (DNA) -> C (mRNA) - G (DNA) -> C (mRNA) - T (DNA) -> A (mRNA) - T (DNA) -> A (mRNA) - C (DNA) -> G (mRNA) - A (DNA) -> U (mRNA) - C (DNA) -> G (mRNA)

- Compile the mRNA sequence

Combine all the mRNA bases found in Step 2 to form the mRNA sequence: GGCUUCCAAUG.

Key concepts

Complementary Base Pairing

Complementary base pairing is a fundamental concept in genetics. It describes how DNA and RNA strands interact through specific base pairs. In DNA, the pairs are adenine (A) with thymine (T), and cytosine (C) with guanine (G). For RNA, thymine is replaced by uracil (U), so adenine pairs with uracil instead. This pairing ensures that the genetic information is accurately copied during processes like DNA replication and transcription.
This principle is important for understanding how a DNA template strand is transcribed into an mRNA strand. Each DNA base determines a complementary RNA base. For example:

• Cytosine (C) pairs with Guanine (G)
• Guanine (G) pairs with Cytosine (C)
• Adenine (A) pairs with Uracil (U)
• Thymine (T) pairs with Adenine (A)

Knowing these pairs can help you predict the mRNA sequence produced from a DNA template.

mRNA Synthesis

mRNA synthesis is the process where a messenger RNA (mRNA) molecule is formed from a DNA template. This process is called transcription. During transcription, an enzyme called RNA polymerase reads the DNA strand and builds the mRNA molecule.
Transcription starts when RNA polymerase binds to a specific sequence on the DNA, called the promoter. It then unwinds the DNA and starts adding complementary RNA nucleotides to the growing mRNA strand. As the enzyme moves along the DNA, it continues to build the mRNA molecule until it reaches a termination signal.
This newly formed mRNA strand then carries the genetic information from the DNA out of the nucleus and into the cytoplasm, where it can be used to make proteins. The accuracy of this process is crucial for the correct expression of genes.

Genetic Code

The genetic code is the set of rules that define how the sequence of nucleotides in DNA and RNA is translated into proteins. Each sequence of three nucleotide bases, called a codon, corresponds to a specific amino acid or a stop signal during protein synthesis.
The genetic code is nearly universal, meaning it is shared by almost all organisms on Earth. This code ensures that genetic information is consistently interpreted, regardless of the organism.
Here is how codons work:

• A codon is a sequence of three nucleotides in mRNA.
• Each codon corresponds to a specific amino acid or a stop signal.
• For example, the mRNA codon AUG codes for the amino acid methionine and also serves as a start signal for protein synthesis.

Understanding the genetic code allows scientists to predict the amino acid sequence of proteins from the mRNA sequence, which is crucial for genetic research and biotechnology.

Transcription Process

The transcription process is the first step in gene expression, where DNA is copied into mRNA. Here are the main stages:
1. **Initiation**: RNA polymerase binds to the promoter region of the DNA. This signals the DNA to unwind so the enzyme can read the bases.
2. **Elongation**: RNA polymerase moves along the DNA, adding RNA nucleotides that are complementary to the DNA template strand. This synthesizes the mRNA strand.
3. **Termination**: When RNA polymerase reaches a termination signal in the DNA, it releases the newly made mRNA strand and detaches from the DNA.
After transcription, the mRNA strand undergoes processing, such as splicing, capping, and adding a poly-A tail, before it leaves the nucleus. These modifications help protect the mRNA and guide it to the ribosome for translation.

• **Initiation**: RNA polymerase binds to DNA promoter region.
• **Elongation**: RNA polymerase synthesizes mRNA based on DNA sequence.
• **Termination**: RNA polymerase releases mRNA at termination signal.

The transcription process ensures that genetic information in DNA is accurately transformed into a molecule that can direct protein synthesis.