Mutations pp. 224-226 and 231

Mutation A change in a genetic trait Either 1) chromosomal or 2) gene mutation Germ cell (gametes) or somatic cell (body) - Germ cell mutations can be inherited and somatic cell mutations result in cancers Can be lethal (deadly) even before birth

Chromosomal Mutations

Deletion loss of a piece of chromosome EX. Cri du chat & Wolf-Hirschhorn syndrome Cri du chat, which is caused by the deletion of part of the short arm of chromosome 5 "Cri du chat" means "cry of the cat" in French, and the condition was so-named because affected babies make high-pitched cries that sound like those of a cat. Affected individuals have wide-set eyes, a small head and jaw, and are moderately to severely mentally retarded and very short. Wolf-Hirschhorn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and severe to profound mental retardation.

Inversion Translocation chromosome breaks off and reattaches in reverse Translocation piece breaks off and attaches to another * No problems in an individual since all genes are intact but there are problems with crossing over during meiosis

- Trisomy - one too many chromosomes (2n=47) nondisjunction: failure of a chromosome to separate from its homologous chromosome - Trisomy - one too many chromosomes (2n=47) EX Down Syndrome, Kleinfelter’s Syndrome (XXY) - Monosomy - only one of a homologous pair (2n=45) EX. Turner Syndrome (X) Men with Klinefelter syndrome are usually sterile, and tend to have longer arms and legs and to be taller than their peers. Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia. During puberty, without testosterone treatment, some of them may develop gynecomastia. Occurring in 1 out of every 2500 girls, the syndrome manifests itself in a number of ways. There are characteristic physical abnormalities, such as short stature, swelling, broad chest, low hairline, low-set ears, and webbed necks.[3] Girls with Turner syndrome typically experience gonadal dysfunction (non-working ovaries), which results in amenorrhea (absence of menstrual cycle) and sterility. Concurrent health concerns are also frequently present, including congenital heart disease, hypothyroidism (reduced hormone secretion by the thyroid), diabetes, vision problems, hearing concerns, and many autoimmune diseases.[4] Finally, a specific pattern of cognitive deficits is often observed, with particular difficulties in visuospatial, mathematical, and memory areas.[5]

Karyotype: photo of chromosomes block cells in cell division and stain the condensed chromosomes with dye thinnest bands contain over a million base pairs and hundreds of genes bands can be used to identify chromosomes and possible genetic disorders due to the wrong number of chromosomes

Gene mutation a change in the genetic code of one gene only one trait is affected Point mutation: substitution, addition, or removal of a nucleotide

Substitution results in new codon (could be same amino acid or stop) EX. Sickle cell anemia

Frame shift mutation removal or addition of a nucleotide causes shift in entire sequence