14.2: What Are the Effects of Mutation?

factors that determines effect of mutation

• size - larger the mutation more significant effects

• position - occurs either in genes or regions in genomes not used for coding - if in genes can result in change in protein synthesis

synonymous mutation

change of one nucleotide to another within a codon that doesn’t affect coded amino acid

non-synonymous mutations

a nucleotide substitution that changes the coded amino acid sequence - missense, nonsense and gain of function mutations

loss of function mutations

results in a gene product that is reduced or completely inactive.

types of loss of function mutations

point mutations, deletions, and insertions that disrupt gene function or protein production.

gain of function mutations

result in a gene product with new or enhanced activity

point mutation

change in single nucleotide in sequence - includes substitution, insertion or deletion which can potentially affect product function

types of point mutation

silent, missense, nonsense, frameshift

2 types of base substitution

transition - when purine is replaced by other purine and pyrimidine replaced by other pyrimidine

transversion - when a purine is replaced by a pyrimidine or vice versa.

silent mutations

substitutions that has no effect on amino acid sequence of protein as codes for same amino acid = function protein

missense mutation

substitution of one amino acid for another in a protein, potentially altering its function or resulting in defective protein

nonsense mutation

creates a premature stop codon in the amino acid sequence, leading to a truncated, usually nonfunctional protein.

frameshift

insertion or deletion of nucleotides in a DNA sequence, which alters the reading frame of the gene, potentially leading to significant changes in the resulting protein.

types of chromosomal rearrangements

mutations that cause changes to chromosome structure - deletion duplication inversion and translocation

deletion

removal of part of genetic material

duplication

homologous chromosomes break at different positions and then reconnects to wrong partners = 1 of 2 chromosomes ends up with deleted segment and other has 2 copies of same segment

inversion

breaking and rejoining causes DNA to run in opposite direction from original

translocation

chromosomal segment breaks off and becomes attached to different chromosome

copy number variation

a type of mutation where sections of the genome are duplicated or deleted, resulting in differences in the number of copies of certain genes.

Single Nucleotide Polymorphisms (SNPs)

variations at a single nucleotide position in the genome, which can contribute to genetic diversity and may influence traits and disease susceptibility.

retroviruses

a type of virus that uses RNA as its genetic material and incorporates its genome into the host cell's DNA through reverse transcription.