If a base-pair change occurs in DNA, this a. is a mutation. b. would be a mutation only if it falls in a protein-coding part of a gene. c. would be a mutation only if it falls in a transcribed part of the genome. d. is not a mutation, because only one base pair has been altered.

Verified step by step guidance

1. Understand the definition of a mutation: A mutation is any change that occurs in the sequence of DNA, regardless of its location or the number of bases involved.
2. Identify what a base-pair change implies: A base-pair change means that one of the base pairs in the DNA sequence has been altered, which could be a substitution, deletion, or insertion of bases.
3. Consider the effect of the location of the mutation: While the effect of a mutation can vary depending on whether it occurs in a coding or non-coding region, the definition of a mutation does not depend on its location.
4. Evaluate the options given in the question: Option (a) states that any base-pair change is a mutation, which aligns with the definition of a mutation. The other options limit the definition of a mutation to specific regions or imply that a single base change is not a mutation.
5. Choose the correct answer based on the definition and characteristics of mutations: The correct answer is (a) because a mutation is defined as any change in the DNA sequence, regardless of its size or location.

Key Concepts

Mutation

A mutation is a change in the DNA sequence that can occur due to various factors, such as environmental influences or errors during DNA replication. Mutations can be classified as point mutations, where a single base pair is altered, or larger-scale changes affecting multiple nucleotides. They can have varying effects on an organism, ranging from benign to harmful, depending on their location and nature.

Protein-Coding Genes

Protein-coding genes are segments of DNA that contain the instructions for synthesizing proteins, which are essential for various cellular functions. Mutations occurring within these regions can lead to changes in the protein's structure and function, potentially resulting in diseases or altered traits. Understanding the distinction between coding and non-coding regions is crucial for assessing the impact of mutations.

Transcription and Transcribed Regions

Transcription is the process by which DNA is copied into RNA, specifically messenger RNA (mRNA), which then serves as a template for protein synthesis. Transcribed regions include both protein-coding sequences and non-coding RNA genes. Mutations in these areas can affect gene expression and the resulting RNA products, influencing cellular behavior and organismal traits.