Changes to a single nucleotide, classed as silent, missense or nonsense depending on the effect on the protein.
Substitutions are silent (same amino acid, due to codon redundancy), missense (different amino acid) or nonsense (premature stop). Transitions (purine to purine) are more common than transversions.
A single missense mutation caused sickle cell disease (GAG to GTG).
Changes to a single nucleotide, classed as silent, missense or nonsense depending on the effect on the protein.
Point Mutations is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Frameshift Mutation, Dominant and Recessive, Inherited Disorders.
Nonsense mutations in the CFTR gene produce truncated proteins and severe cystic fibrosis.
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Point Mutations. Intermediate topics assume the Beginner vocabulary.
The closest topics to Point Mutations are Frameshift Mutation, Dominant and Recessive, Inherited Disorders, Homozygous and Heterozygous. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Point Mutations. To practise the whole of Genetics, use the Genetics quiz.
Point Mutations: Changes to a single nucleotide, classed as silent, missense or nonsense depending on the effect on the protein. Frameshift Mutation: Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Frameshift Mutation and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.
Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons.
🧬 GeneticsA dominant allele shows its effect when present in one copy; a recessive allele only shows when two copies are present.
🧬 GeneticsConditions caused by faulty genes passed through families, such as cystic fibrosis and sickle cell disease.
🧬 GeneticsHomozygous means two identical alleles for a gene; heterozygous means two different alleles.
🧬 Genetics