9 26 lecture summary Mutations Cancer cells have high mutation rates Mutations abrupt changes in genetic material occur typically in cell division Mutations are important when they happen in tissues that are sent to offspring testes ovaries Somatic mutations Mutations in cells other than sex cells not passed to next gen Types of mutation 1 Structural changes in chromosome occurs mainly when a screw up in meiosis a Loss or duplication of whole genes Deletions whole chunks of DNA lost Duplications whole chunks replicated b Changes in gene arrangement Translocation large pieces of chromosome moved to another place on genome Transposons jumping genes small pieces of DNA shifting within gene Inversions chunks of chromosome flipping over 2 Numerical changes in chromosomes a Aneuploidy addition of one or more chromosomes xxy xxyy xxxy etc Mutations are not all due to mother More cell divisions more chance of mutation Sperm cells divide every 15 days 3 Gene point mutations nucleotide changes b Polyploidy multiple copies of entire genome liver or intestinal cells a Substitution mutation could code for same amino acid b Addition moves nucleotides down the chain Frame shift Subtraction also causes frame shift c d Protein chain length modifiers start stop codons leads to short or extra long non functional protein Mutation in developmental genes Heterochronic mutations Alter rates of grown of some organs relative to others in organism Many differences in species due to regulatory genes Allometry comparing growth rates between tissues and structures Shifts in growth gradients change in time of development Trasnformations of species by genetic changes Regulating embryonic chemical gradients Homeotic Genes homeotic gene pattern of body formation during early embryonic development of organisms any of a group of that control the genes
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