Mutation and The Phenotype

A mutation is an unpredictable change in the genotype of a cell that results from damage to, or imperfect replication of, the DNA, or from faulty operation of mitosis or meiosis.
Can be a gene mutation or chromosome mutation.
Mutation is a rare event.
Mutation takes place in a single cell, but cannot usually be detected until the mutant cell is replicated and a distinctive phenotype has been produced.
Some chemicals, mutagens, increase the chance of mutation because they react with DNA or interfere with replication.
Some types of radiation, such as X-rays, cause mutation by damaging DNA.

A gene mutation affects the nucleotide sequence of a section of DNA so that the triplet code for the primary structure (amino acid sequence) of the polypeptide coded by the gene is changed.
One or more nucleotides may be deleted from, or added to, the sequence. This alters the reading frame of the triplet code, altering all subsequent triplet codes.
One nucleotide may be substituted for another, producing a different triplet code which may code for a different amino acid or be…

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