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Put your HW in the HW folder.

Put your HW in the HW folder. What do all of the following have in common?. Genetic Changes. Chapter 11.3. MUTATION. defined as a change in the DNA sequence can be caused by errors in replication , transcription , cell division , or by external agents. Mutations. Reproductive cells

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Put your HW in the HW folder.

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  1. Put your HW in the HW folder. • What do all of the following have in common?

  2. Genetic Changes Chapter 11.3

  3. MUTATION • defined as a change in the DNA sequence • can be caused by errors in replication, transcription, cell division, or by external agents

  4. Mutations • Reproductive cells • Will be passed down to offspring • Embryo may not survive • Offspring might be sterile • Body cells • Impair cell function • Cancer • Premature aging

  5. Point Mutation: Single base alteration What do you see happening?

  6. Sickle cell anemia

  7. Frameshift Mutation A type of point mutation: single base is added or deleted from DNA How is this different than a point mutation? How is it similar?

  8. Frameshift cont’d • If groups of 3 (or multiples of 3) bases is added or deleted, it will only affect a few amino acids (1 per codon) • If 1, 2, 4 (any non-multiple of 3) is deleted, ALL amino acids will be different from the mutation onward. • Causes a change in the reading frame

  9. Cystic fibrosis – affects the lungs, liver, pancreas, small intestine, reproductive organs, and the skin

  10. Chromosomal mutations • When there are changes in the chromosome, it is considered a chromosomal mutation. • Part of a chromosome is broken off and lost • There are 4 kinds of chromosomal mutations: • Deletions, Insertions, Inversions, Translocations • Break and rejoin incorrectly • Nondisjunction

  11. Deletion: Section is lost from a chromosome

  12. Insertion: Section of 1 chromosome is added to another

  13. Inversion: segment of chromosome reverses itself

  14. For each #, what is different between the chromosome on the left to the one on the right?

  15. Translocation: Sections of 2 different chromosomes are swapped

  16. Nondisjunction Results in a change in the chromosome # in the daughter cells Polyploidy

  17. Polyploidy in strawberries Wild type Commercially propagated varieties Each cell is 1n Each cell is 8n  8 copies of each chromosome!

  18. Polyploidy in Dianthus

  19. More examples: • Consider a normal chromosome with genes in alphabetical order: a b c d e f g h i 1. Deletion: part of the chromosome has been removed: a b c g h i 2. Dupliction(Insertion): part of the chromosome is duplicated: a b c d e f d e f g h i 3. Inversion: part of the chromosome has been re-inserted in reverse order: a b c f e d g h i

  20. More examples cont. 4. translocation: parts of two non-homologous chromosomes are joined: If one normal chromosome is a b c d e f g h i and the other chromosome is u v w x y z, then a translocation between them would be a b c d e f x y z and u v w g h i.

  21. Causes of Mutations • random, mistake in base pairing • mutagens (ex. radiation, chemicals, high temperature)

  22. Radiation • contains energy that can damage or break apart DNA • breaking and reforming of DNA can result in deletions • may convert one base into another or fuse two bases together

  23. Chemical mutagens • include asbestos, benzene, and formaldehyde • usually cause substitution mutations

  24. Sources of formaldehyde

  25. DNA repair • “Proofreading” is performed by enzymes like DNA ligase. • Such repair mechanisms work very efficiently, although they are not perfect. • Thus, it is still best to avoid situations that would expose us to mutagens.

  26. HW for 3/13 • Due tomorrow: • Worksheet on DNA/RNA and mutations • Field trip permission slip and $5 • Due Friday: Ch.12 Index Cards

  27. Problem-Solving Lab 11-3 (p. 299) • In your groups, answer questions 1-4 on a blank sheet of paper with everyone’s name on it. • Group with the most correct answers gets 2 bonus points for the day. • You have 7 min – starting now!

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