1 / 74

BIOE 109 Summer 2009 Lecture 4- Part I Mutation and genetic variation

BIOE 109 Summer 2009 Lecture 4- Part I Mutation and genetic variation. Four basic processes that can explain evolutionary changes:. Mutation 2. Gene Flow 3. Genetic drift 4. Natural selection. Sources of genetic variation Crossing over during meiosis- creates new

mauve
Télécharger la présentation

BIOE 109 Summer 2009 Lecture 4- Part I Mutation and genetic variation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. BIOE 109 Summer 2009 Lecture 4- Part I Mutation and genetic variation

  2. Four basic processes that can explain evolutionary changes: • Mutation • 2. Gene Flow • 3. Genetic drift • 4. Natural selection

  3. Sources of genetic variation • Crossing over during meiosis- creates new • combinations of alleles on individual chromosomes • 2. Independent assortment- creates new combinations • chromosomes in the daughter cells

  4. Sources of genetic variation • Crossing over during meiosis- creates new • combinations of alleles on individual chromosomes • 2. Independent assortment- creates new combinations • chromosomes in the daughter cells • 3. Mutations- create completely new alleles and genes

  5. General classes of mutations

  6. General classes of mutations Point mutations “Copy-number” mutations Chromosomal mutations Genome mutations

  7. Point mutations

  8. Point mutations There are four categories of point mutations:

  9. Point mutations There are four categories of point mutations: 1. transitions (e.g.,A  G, C  T)

  10. Point mutations There are four categories of point mutations: 1. transitions (e.g.,A  G, C  T) 2. transversions (e.g., T  A, C  G)

  11. Point mutations There are four categories of point mutations: 1. transitions (e.g.,A  G, C  T) 2. transversions (e.g., T  A, C  G)

  12. Point mutations There are four categories of point mutations: 1. transitions (e.g., A  G, C  T) 2. transversions (e.g., T  A, C  G) 3. insertions (e.g., TTTGAC  TTTCCGAC)

  13. Point mutations There are four categories of point mutations: 1. transitions (e.g., A  G, C  T) 2. transversions (e.g., T  A, C  G) 3. insertions (e.g., TTTGAC  TTTCCGAC) 4. deletions (e.g., TTTGAC  TTTC)

  14. Point mutations There are four categories of point mutations: 1. transitions (e.g., A  G, C  T) 2. transversions (e.g., T  A, C  G) 3. insertions (e.g., TTTGAC  TTTCCGAC) 4. deletions (e.g., TTTGAC  TTTC) • in coding regions, point mutations can involve silent (synonymous) or replacement (nonsynonymous) changes.

  15. Point mutations There are four categories of point mutations: 1. transitions (e.g., A  G, C  T) 2. transversions (e.g., T  A, C  G) 3. insertions (e.g., TTTGAC  TTTCCGAC) 4. deletions (e.g., TTTGAC  TTTC) • in coding regions, point mutations can involve silent (synonymous) or replacement (nonsynonymous) changes. • in coding regions, insertions/deletions can also cause frameshift mutations.

  16. Loss of function mutations in the cystic fibrosis gene

  17. “Copy-number” mutations

  18. “Copy-number” mutations • these mutations change the numbers of genetic elements.

  19. “Copy-number” mutations • these mutations change the numbers of genetic elements. •gene duplication events create new copies of genes.

  20. “Copy-number” mutations • these mutations change the numbers of genetic elements. •gene duplication events create new copies of genes. • one important mechanism generating duplications is unequal crossing over.

  21. Unequal crossing-over can generate gene duplications

  22. Unequal crossing-over can generate gene duplications

  23. Unequal crossing-over can generate gene duplications lethal?   neutral?

  24. “Copy-number” mutations • these mutations change the numbers of genetic elements. •gene duplication events create new copies of genes. • one mechanism believed responsible is unequal crossing over. • over time, this process may lead to the development of multi-gene families.

  25.  and -globin gene families Chromosome 11 Chromosome 16

  26. Timing of expression of globin genes

  27. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns!

  28. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba

  29. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba  Alcohol dehydrogenase (Adh) Chromosome 2 Chromosome 3

  30. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba  mRNA  Alcohol dehydrogenase (Adh) Chromosome 2 Chromosome 3

  31. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba  mRNA  cDNA  Alcohol dehydrogenase (Adh) Chromosome 2 Chromosome 3

  32. Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba  mRNA  cDNA   Alcohol dehydrogenase (Adh) “jingwei” Chromosome 2 Chromosome 3

  33. Whole-genome data yields data on gene families

  34. “Copy-number” mutations •transposable elements (TEs) are common.

  35. “Copy-number” mutations •transposable elements (TEs) are common. • three major classes of TEs are recognized:

  36. “Copy-number” mutations •transposable elements (TEs) are common. • three major classes of TEs are recognized: 1. insertion sequences (700 – 2600 bp) 

  37. “Copy-number” mutations •transposable elements (TEs) are common. • three major classes of TEs are recognized: 1. insertion sequences (700 – 2600 bp)  2. transposons (2500 – 7000 bp)

  38. “Copy-number” mutations •transposable elements (TEs) are common. • three major classes of TEs are recognized: 1. insertion sequences (700 – 2600 bp)  2. transposons (2500 – 7000 bp) 3. retroelements

  39. Chromosomal inversions lock blocks of genes together

  40. Inversions act to suppress crossing-over…  inviable  inviable

  41. Inversions act to suppress crossing-over…  inviable  inviable … and can lead to co-adapted gene complexes

  42. Chromosomal inversions in Drosophila pseudoobscura Here is a standard/arrowhead heterozygote:

  43. Here are more inversion heterzygotes:

  44. Chromosomal translocations are also common

  45. Changes in chromosome number are common

  46. Changes in chromosome number are common • in mammals, chromosome numbers range from N = 3 to N = 42.

  47. Changes in chromosome number are common • in mammals, chromosome numbers range from N = 3 to N = 42. • in insects, the range is from N = 1(some ants) to N = 220 (a butterfly)

  48. Changes in chromosome number are common • in mammals, chromosome numbers range from N = 3 to N = 42. • in insects, the range is from N = 1(some ants) to N = 220 (a butterfly) • karyotypes can evolve rapidly!

  49. Muntiacus reevesi Muntiacus muntjac

  50. Muntiacus reevesi; N = 23 Muntiacus muntjac; N = 4

More Related