Variation and Mutation

Effects of Mutations

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Content Contributors
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Ben Whitten

Learning Objectives

  • Understand the types of effects from mutations; neutral, deletorious and beneficial

  • Explain how beneficial mutations are rare

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Context of Mutation Effects
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It is vital to know that a protein's function is dependent on its structure


Any mutation that alters a protein's structure can create consequences for protein function, with the potential of having large impacts on the survival of the organism. 


Mutations can thus be categorised as neutral, deleterious, or beneficial mutations.

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What are neutral mutations?
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Neutral mutations result in an unchanged protein product (in the case of a synonymous mutation), so therefore the organism's survival is unaffected


Missense substitutions can also be neutral, given that the original amino acid is interchanged with another that has similar properties to its previous amino acid.

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What are deleterious mutations?
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Deleterious mutations disrupt the function of proteins, which decreases the organism's ability to survive and function normally. 


Nonsense mutations are usually deleterious as they result in the production of a non-functional, incomplete protein. It's important to note that most mutations are deleterious.

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What are beneficial mutations?
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On certain occasions, gene mutations have the possibility of producing a new allele which actually benefits the survival of the organism. 


For example, it may be a missense mutation that changes the function of the original protein, or perhaps a nonsense mutation that eliminates a harmful protein. It's important to note that these mutations are uncommon.

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Causes of Mutations
Chromosomal Mutations
Point Mutations
Effects of Mutations
Sexual Reproduction and Variation
Phenotypic Expression
Environmental Factors
Variation
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