#point mutation

BOTANY

Which type of mutation involves a change in a single nucleotide without shifting the reading frame?

A point mutation occurs when a single nucleotide is altered, but it does not affect the reading frame. This follows from NCERT principle where relation explains outcome clearly for students.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.

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Sex Determination Mutation and Genetic Disorders

Which type of mutation involves a change in a single nucleotide without shifting the reading frame?

A point mutation occurs when a single nucleotide is altered, but it does not affect the reading frame.

Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders

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Sex Determination Mutation and Genetic Disorders

Which of the following genetic disorders is caused due to a point mutation in the β-globin gene?

Sickle-cell anemia is caused by a single base substitution in the β-globin gene, leading to the formation of abnormal hemoglobin.

Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders

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Sex Determination Mutation and Genetic Disorders

Which type of mutation results from a single base substitution in DNA?

A point mutation occurs when a single base is changed, as seen in sickle-cell anemia.

Ref: NCERT Class 12 Biology Chapter 4: Principles of Inheritance and Variation Sex Determination Mutation and Genetic Disorders

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Mutation and Mutagenesis

Missense mutation leads to

Missense mutation is non-synonymous point substitution changing single codon to encode different amino acid, altering polypeptide primary sequence at one position. Impact ranges from conservative replacement preserving charge and size with minimal effect to radical change disrupting hydrophobic core, active site, or protein-protein interface. Mutant protein may exhibit reduced stability, altered kinetics, or dominant-negative interference. Classic illustration is hemoglobin S where glutamate at position six becomes valine, promoting polymerization under deoxygenation and sickling phenotype. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 9: Missense Mutation Consequences for Protein Structure

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