Concept explainers
If a point mutation occurs within a human egg cell genome that changes an A to a T, what is the most likely effect of this mutation on the
To determine: The phenotypic effect of a point mutation in an offspring.
Introduction: A change of one base pair to another in a DNA molecule is called point mutation. A change of one nucleotide of a triplet within a protein-coding portion of a gene results in a new triplet that codes for a different amino acid in the protein product.
Explanation of Solution
The phenotypic effect of any base change is dependent on a number of factors. These factors are as follows:
- Location of the base pair in coding or noncoding region.
- Interaction with other base sequences in the genome.
- Base pair potential in dominance or recessiveness.
If a base change is located in a noncoding region, there may be no influence on the phenotype. Some noncoding region serves regulatory functions. The mutations that influence transcription levels, polyA addition, splicing, and translation can affect phenotype.
If a mutation occurs in a coding region that acts as a full recessive, there should be no influence on the phenotype. If a mutant gene acts as a dominant, then there would be an influence on the phenotype.
Thus, the phenotypic effect of point mutation depends on the location of the base pair, interaction with base pair, and potential of base pair.
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