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Mutations

Mutations. 5.6. Introduction. Mutation: error made in DNA sequence that is inherited. (Must be in the __________ cells). Could have deleterious side effects, no effects, or positive effects. Deleterius : cystic fibrosis Positive effect: natural selection.

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Mutations

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  1. Mutations 5.6

  2. Introduction • Mutation: error made in DNA sequence that is inherited. • (Must be in the __________ cells). • Could have deleterious side effects, no effects, or positive effects. • Deleterius: cystic fibrosis • Positive effect: natural selection. • No effect: mostly in eukaryotes (two copies of each gene).

  3. Types of Mutations • Silent Mutation: no effect on operation of cell 1) occur in noncoding regions, ______. 2) Redundancy of genetic code: UUU and UUC both code for phenylalanine. Mistake in 3rd base during transcription would not change PP translated. • Missense mutation • Change in base sequence alters a codon different AA. • Ex// sickle cell anemia • Nonsense mutation • Change in DNA causes stop codon to replace codon specifying for an AA. • Often lethal to the cell

  4. Point mutations – specific to one base pair • Substitution • One base pair substituted for another. • Frameshift Mutation • When mutation causes change in the reading frame • Deletion • One or more nucleotides removed. • Very drastic shift in reading frame! (all AA beyond the mutation may be altered!) • Insertion • One or more nucleotides inserted. • Similar consequence to deletion.

  5. Question Will an insertion or deletion of 3 sequential nucleotides cause a frameshift mutation? Is this as serious as a frameshift mutation as one or two nucleotides?

  6. Translocation • Apparent at the chromosomal level • Relocation of groups of base pairs from one part of the genome to another. • Two segments of chromosomes break and exchange places. • leukemia

  7. Transposable elements • “jumping genes” • Move from one location to another in the genome: if fall on coding region, could disrupt the correct transcription of the gene.

  8. Inversion • Chromosomal segment that has reversed its orientation in the chromosome.

  9. Causes of Genetic Mutations • Spontaneous mutation • Simple errors of genetic machinery. • (Poly I and III usually act as spell-checkers, but can miss errors sometimes). • Induced mutations • Due to exposure from mutagenic agents • UV radiation, X rays, certain chemicals.

  10. Mutagens UV light • Ozone layer usually acts as a protective translucent shield against high-energy (UV) light. • Depletion in ozone  increased high-energy (UV)  increase in point mutations. X-ray • Can break SP backbone  automatically annealed by DNA-repairing enzymes (which can make mistakes)  base pairs can be lost

  11. Cancer • Considered a genetic disease • Mutations result in oncogenes: mutant versions of genes that control cell growth and division.

  12. Cystic Fibrosis • Caused by one of at least 60 different types of mutation in the CFTR gene (cystic fibrosis transmembrane regulator)  severity depends on location of the mutation. • Causes thick, sticky mucus in the lungs along with other symptoms.

  13. Pesticides • Linked to deleterious mutations: many banned in Canada. http://www.youtube.com/watch?v=nQzx2ZyaSbw&feature=related

  14. DNA-resembling mutagens • Some chemicals resemble DNA and can cause mutations • AIDS therapy: some AIDS drugs resemble nitrogenous bases in DNA and insert themselves into the virus`s DNA. • When viral DNA is to be duplicated, DNA polymerase stops  does not recognize chemical as a base  progression of disease is slowed.

  15. Seatwork/Homework Page 263, #1-8

  16. Independent Reading/Study • Read section 5.7. Make short notes in your notebook. • PPs 1-3 • Read section 5.8. Make short notes in your notebook. • PP 1 & 2

  17. Biotechnology Assignment • Each student will be assigned one of the following biotechnological processes/ideas: • Restriction Endonucleases (answer PP 1-5) • Gel Electrophoresis (answer PP 11-15) • Plasmids (answer PP 16-18) • Transformation (answer PP 19-22) In a PP presentation, summarize your assigned process. (in 10-15 minutes)You must present this to the class, and supply the class with handouts of the information.

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