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Molecular Basis for Relationship between Genotype and Phenotype. genotype. DNA. DNA sequence. transcription. RNA. translation. amino acid sequence. protein. function. phenotype. organism. Frameshift Mutations and Suppressor Mutations.
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Molecular Basis for Relationship between Genotype and Phenotype genotype DNA DNA sequence transcription RNA translation amino acid sequence protein function phenotype organism
Frameshift Mutations and Suppressor Mutations frameshift mutations: insertions or deletions of nucleotides that cause a shift in the translational reading frame suppressor mutations: mutations that counteract or suppress the effects of another mutation wild-type CAUCAUCAUCAUCAU HIS HIS HIS HIS HIS addition of A deletion of A CAUACAUCAUCAUCAU__ HIS THR SER SER SER . CAUACUCAUCAUCAU HIS THR HIS HIS HIS deletion of U addition of G CAUCACAUCAUCAU__ HIS HIS ILE ILE . CAUCACGAUCAUCAU HIS HIS ASP HIS HIS
Mutation: Levels of Hereditary Change Gene (Point) Mutation: One allele changes to a different allele. Effects are limited to that locus. Chromosome Mutation: Changes occur at the chromosome level. Multi-locus effects are not unusual.
Molecular Basis for Relationship between Genotype and Phenotype genotype DNA DNA sequence transcription RNA translation amino acid sequence protein function phenotype organism
Point mutations at the molecular level Base substitution: change in base of nucelotide pair Base additions: insertion of nucleotide pairs Base deletions: deletion of nucleotide pairs
Mutation frequencies obtained with various mutagens in Neurospora Mutagens are agents that cause mutations. Anything that is capable of causing chemical changes in the structure of DNA (especially bases) is a mutagen. Mutagens differ in mutagenicity.
The Ames Test Reveals Mutagenic Compounds Strain 1 - frameshift mutation Strain 2 - base substitution
Ames Test Results1 Revertant colonies per culture plate. Treatment Control diethyl sulfate* ICR-191** TA1575 11 14,700 13 TA1578 25 0 450 TA1575 : his base substitution mutant TA1578 : his frameshift mutant * Highly toxic alkylating agent, occurs as colorless liquid with peppermint odor ** Acridine, colorless solid intercalating agent, known carcinogen 1 McCann etal., 1975. Proc. Natl. Acad. Sci. USA 72 979-983.