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Mutation
Definition: a change that occurs in our DNA sequences.
Mutation Causes
Mistakes are made when DNA is being copied through DNA replication. Results of exposure to environmental factors like UV light, cigarette smoke, and radiation.
Cell Repair
Cells can sometimes repair the error or possible damage before it becomes a fixed mutation (permanent).
Mutation Dis/Advantages
Advantages: Some can have a positive effect → genetic variation
Disadvantages: Some disrupt normal activity that can cause diseases like cancer. Environmental factors introduce radicals that attack DNA, causing these diseases.
Types of Mutations
Genes and Chromosomal Mutations
Point Mutation
Affect a single point in DNA, and one base is substituted for another.
Includes
Missense
Silent
Nonsense
Missense
The substitution changes the amino acid. Essentially it changes it to not make sense. Creates an abnormal protein.
A type of point mutation.
Silent
The substitution does not change the amino acid. Change will occur, however, you won’t even know it’s there. Codons translate to the same product.
Nonsense
The amino acid is changed to a “stop” codon. “Does not make sense to stop the code right in the middle.” A lot of the times when the protein isn’t made.
Frameshift Mutations
The “reading frame” changes, which changes the amino acid sequence.
Includes:
Deletion
Insertion
Creates a domino effect, possibly producing a malfunctioning protein.
Deletion
A base is lost (-).
Insertion
An extra base is added (+).
