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MUTATIONS

MUTATIONS. Types of mutations Causes Consequences Examples. What is a mutation ?. A mutation  is any change in the nucleotide sequence of an organism's DNA.

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MUTATIONS

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  1. MUTATIONS Types of mutations Causes Consequences Examples Biology Y11 2014 - DRM

  2. Whatis a mutation? • Amutation is any change in the nucleotide sequence of an organism's DNA. • Itisanunpredictable, randomchangein the DNA. Mutations can take place in anytype of cell: bacterial, fungal, plant, animal. • Mutations are cumulative in a population. This leads to evolution (changes in time). • Mutations can be neutral, beneficial orharmful. Biology Y11 2014 - DRM 2/13

  3. Types of mutations MUTATIONS • Affectsone to threenucleotides • Changesone gene • Point mutations are changes in the genetic sequence that occur at a specific point along the DNA strand can be chromosomal point • Involvechanges to largesections of a chromosomeoraffectsevenentirechromosomes • Changesmany genes Biology Y11 2014 - DRM 3/13

  4. What causes mutations? Changes in the DNA can be due to: • chance(spontaneousmutations) • mutagens. Examples of mutagensare: • smoking • radiation (solar or nuclear) • toxicchemicals (pesticides, solvents) • hightemperatures Biology Y11 2014 4/13

  5. When and where • Mutationstake place during DNA replication (making a DNA copy) orduring DNA transcription (copyingthe DNA to mRNA) • Mutations can be located in germcellsorsomaticcells. Somatic mutations take place in body cells. Germ-line mutationsoccur in gametes or in cells that eventually produce gametes. These mutations are passed on to an organism's offspring. As a result, future generations of organisms will carry the mutation in all of their cells. Biology Y11 2014 - DRM 5/13

  6. POINT MUTATIONS There are severalways in which nucleotides can change: • InsertionorAddition – addingan extra nucleotide • Deletion – removingonenucleotide • Substitution – changingone base foranother • Inversion – havingthereversedorder in a sequence • Small numberrepeats – addingduplicates of very short sequences Biology Y11 2014 - DRM 6/13

  7. Examples of pointmutations NormalBEAST substitutionFEAST Insertion BREAST Inversion BEATS DeletionBEST Biology Y11 2014 - DRM 7/13

  8. Consequences of pointmutations Mutationschangetranscription, thereforetheyaffectthe “readingframe”. As a result, proteinsmayhavedifferent amino acids, or be terminatedsooner. Biology Y11 2014 - DRM 8/13

  9. Consequences of base substitutions Missense: the change in DNA sequence changes the codon to a different amino acid. If the amino acid is similar in structure, the mutation is silent or neutral. If the amino acid is different in structure, the mutation leads to a altered protein. This may lead to diseases. Biology Y11 2014 - DRM 9/13

  10. Consequences of base substitutions Nonsense: a change in the genetic code results in the coding for a stop codon rather than an amino acid. The shortened protein is generally non-functional or its function is impeded. This may lead to diseases. Biology Y11 2014 - DRM 10/13

  11. Consequences of insertionsordeletions • Frameshift: The insertion or deletion of a number of bases that is not a multiple of 3. This alters the reading frame of the gene and frequently results in a premature stop codon and protein truncation. Normal DNA THE BIG BAD FLY HAD ONE RED EYE AND ONE BLU EYE. deletion in the 6th nucleotide: THE BIB ADF LYH ADO NER EDE YEA NDO NEB LUE YE. Biology Y11 2014 - DRM 11/13

  12. Examples of deletions AUG AAA CUU CGC AGG AUG AUGAUG AUG AAC UUC GCA GGA UGA UGAUG Biology Y11 2014 - DRM 12/13

  13. summary Biology Y11 2014 - DRM 13/13

  14. Sources http://education-portal.com/academy/lesson/mutagens-and-the-effects-of-frameshift-mutations-definitions-and-examples.html#lesson http://www.nature.com/scitable/topicpage/dna-is-constantly-changing-through-the-process-6524898 http://www.uvm.edu/~cgep/Education/Mutations.html http://www.nature.com/scitable/topicpage/genetic-mutation-441 Biology Y11 2014 - DRM

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