NATS 1610 Lecture Notes - Lecture 4: Thymine, Cytosine, Organelle
Document Summary
In the living cell, dna undergoes frequent chemical change, especially when it is being replicated. Those that are not result in a mutation. Thus mutation is a failure of dna repair. A mutation is any change in an organism"s dna sequence. Proteins, encoded by the genotype, produce the phenotype. Hence, dna mutations affect phenotype only when the mutation is expressed (dna. Rna protein) and the resulting protein functions abnormally. Not all mutations affect the protein"s ability to function and thus do not generate a phenotype. One of the most common types of mutation is the point mutation, a change in a single nucleotide. Point mutations can result from errors in dna replication or from exposure to mutagenic toxins. Silent mutations - mutations that do not change the amino acid sequence of the protein. Missense mutation - a point mutation that causes a change in the amino acid sequence of the protein.
