Coding sequence

Definition

A coding sequence is a portion of a gene that contains the information needed to produce a protein. This sequence is made up of nucleotides, which are grouped into codons that correspond to specific amino acids. Understanding coding sequences is crucial because they directly dictate the structure and function of proteins, playing a central role in gene expression and cellular function.

5 Must Know Facts For Your Next Test

1. Coding sequences are typically found within exons, while introns do not code for proteins.
2. The arrangement of codons in a coding sequence determines the specific order of amino acids in a protein, which affects its shape and function.
3. Mutations in coding sequences can lead to changes in protein structure, potentially causing diseases or altering normal cellular functions.
4. The start codon, usually AUG, signals the beginning of translation for the coding sequence, while stop codons signal termination.
5. Alternative splicing can lead to different proteins being produced from the same coding sequence by including or excluding certain exons.

Review Questions

• How do coding sequences relate to the overall structure of a gene?
  • Coding sequences are integral parts of genes, specifically representing those segments that provide the instructions for building proteins. Within a gene, coding sequences (exons) alternate with non-coding sequences (introns), and only exons remain in the final mRNA after splicing. This relationship is essential because it highlights how genes contain both coding and non-coding regions, influencing gene expression and protein production.
• Discuss how mutations in coding sequences can affect protein function and lead to diseases.
  • Mutations in coding sequences can result in altered amino acid sequences during protein synthesis, which may change the protein's shape and function. For instance, if a mutation leads to a premature stop codon, it can produce a truncated protein that may be non-functional. Such alterations can contribute to various diseases, including genetic disorders and cancers, emphasizing the importance of maintaining the integrity of coding sequences for proper cellular function.
• Evaluate the significance of alternative splicing in relation to coding sequences and protein diversity.
  • Alternative splicing plays a crucial role in expanding protein diversity from a single coding sequence by allowing different combinations of exons to be included in the final mRNA transcript. This process enables one gene to encode multiple proteins, each potentially having distinct functions and properties. Understanding alternative splicing's significance highlights how organisms can adapt and generate complexity in their proteomes without increasing their genetic material, showcasing an elegant solution for functional diversity in biological systems.

Related terms

exons: Exons are the segments of a gene that are retained in the final messenger RNA (mRNA) after splicing, and they contain the coding information for proteins.

introns: Introns are non-coding segments of a gene that are transcribed into precursor mRNA but are removed during RNA processing before translation.

transcription: Transcription is the process by which the DNA sequence of a gene is copied into messenger RNA (mRNA), which then carries the coding information from the nucleus to the ribosome for protein synthesis.