CYTO 9 & 10

• Mutations is defined as a heritable alteration or change
• The term "mutagen" refers to any agent capable of inducing mutations.
• Polymorphism sequence variants with no obvious effect upon phenotype
• Genetic load of the population - harmful alleles of all kinds
• Base substitutions are the most prevalaent & missense mutations
• Substitution - replacement of a single nucleotide by another
• Substitution is the most common type of mutation
• Transition - is the replacement by the same type of nucleotide
• 2 types of substitution: Transversion & Transition
• Deletion is the loss of one or more nucleotides
• Insertion - involves the addition of one or more nucleotides
• Synonymous mutation - if a mutation does not alter the polypeptide product
• Non-synonymous mutations - if a mutation alters the amino acid sequence of the protein
• Chemicals & UV Radiation - these causes mutations
• Skin cancers & Leukemia result from somatic mutation
• 2 Classes of Mutations: Spontaneous & Induced Mutation
• Spontaneous Mutation - caused durng DNA replication
• Induced Mutation - caused by the changes in DNA
• Environmental factors called mutagens
• Types of Mutation : Chromosome Mutations & Gene Mutation
• Chromosome mutation - involves changing the structure of a chromsomes
• 5 types of chromosome mutation: Deletion, Insertion, Duplication, Translocation & non- disjunction
• Deletion - due to breakage, Example: (DiGeorge Syndrome - caused by deletion of chromosome 22
• Inversion - chromosome segment breaks off
• Example of inversion is Hemophilia
• Hemophilia - a diseas that inhibits the ability of blood to clot
• Duplication - occurs when a gene sequence is repeated
• Example of duplication is Pallister Killian Syndrome where chromosome 12 is duplicated
• Translocation - involves 2 chromosomes aren't homologous
• Example of translocation - Down Syndrome which is rearrangement of chromosome
• Non - disjunction - failure of chromosome to separate during meiosis
• XXY Syndrome - Klinefelter's Syndrome
• Gene mutations - change in the nucleotide sequence of a gene
• 5 Types of gene mutations: Point Mutations, Insertions, Substitutions, Deletions & Frameshift
• Point Mutations - change in a single nucleotide
• Mutation of Beta globin chain - Sickle Cell Anemia
• Frameshift - inserting or deleting one or more nucleotides
• Morphological Mutants - type of mutations generate a visible morphological alteraltions
• Lethal Mutants - they are fatal in nature leading to the death o individuals
• Conditional Mutants - are normal under one condition, but abnormal under another