Mutations

Types of Point Mutations

base substitution, base insertion, base deletion

base substitution

a genetic mutation where one nucleotide base in a dna sequence is incorrectly replaced by another

base insertion

a type of mutation where one or more dna bases are added to a dna sequence

base deletion

a type of mutation where one or more dna bases are removed from a dna sequence

synonymous mutation

a type of genetic change where one nucleotide is replaced with another but the resulting amino acid remains the same

missense mutation

a type of point mutation in dna where a single nucleotide change causes a different codon, leading to a single different amino acid being incorporated into a protein (conservative and nonconservative mutations)

conservative mutation 

a genetic change that results in an amino acid substitution with another amino acid that shares similar chemical properties, preserving the original amino acid function and structure within the protein

nonconservative mutation

a type of point mutation where one nucleotide in the dna sequence is changed resulting in a different (chemically dissimilar) amino acid being inserted into the resulting protein

nonsense mutation

a point mutation in dna sequence that results in a premature stop codon

frameshift mutation

a type of genetic mutation that occurs when one or more nucleotides are inserted or deleted from a dna sequence, shifting the reading frame of the gene

constitutive allele

a gene variant that result in continuous and constant expression (protein is produced regardless of conditions); happens when a glycine is turned into any other amino acid 

spontaneous mutation

a random naturally occurring change in the dna sequence of an organism that is not caused by external mutagens but rather by internal processes

What are the mechanisms of spontaneous mutations

1. errors in dna replication

2. replication slippage

3. cellular environment

induced mutations

a deliberate, accelerated change in an organisms dna caused by external factors

mutagens

an agent, such as radiation or chemical substance, which causes genetic mutation

What are the mechanisms of induced mutations?

1. base modification by alkylating agents

2. base damage by bulky adducts

3. incorporation of base analogs

4. binding of intercalating agents

5. base damage by ultraviolet light

6. base damage and modification and dna strand breaks by ionizing radiation