* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download (Part 2) Mutation and genetic variation
Non-coding DNA wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Segmental Duplication on the Human Y Chromosome wikipedia , lookup
Copy-number variation wikipedia , lookup
Minimal genome wikipedia , lookup
Human genome wikipedia , lookup
Human genetic variation wikipedia , lookup
Gene therapy wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Genomic imprinting wikipedia , lookup
Public health genomics wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetic engineering wikipedia , lookup
Gene nomenclature wikipedia , lookup
Population genetics wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Epigenetics of neurodegenerative diseases wikipedia , lookup
Gene desert wikipedia , lookup
Neuronal ceroid lipofuscinosis wikipedia , lookup
X-inactivation wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
Gene expression profiling wikipedia , lookup
Koinophilia wikipedia , lookup
Gene expression programming wikipedia , lookup
Saethre–Chotzen syndrome wikipedia , lookup
Transposable element wikipedia , lookup
Genome editing wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Designer baby wikipedia , lookup
Helitron (biology) wikipedia , lookup
Genome evolution wikipedia , lookup
Frameshift mutation wikipedia , lookup
Genome (book) wikipedia , lookup
Oncogenomics wikipedia , lookup
BIOE 109 Summer 2009 Lecture 4- Part I Mutation and genetic variation Four basic processes that can explain evolutionary changes: 1. Mutation 2. Gene Flow 3. Genetic drift 4. Natural selection Sources of genetic variation 1. Crossing over during meiosis- creates new combinations of alleles on individual chromosomes 2. Independent assortment- creates new combinations chromosomes in the daughter cells Sources of genetic variation 1. 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 General classes of mutations General classes of mutations Point mutations “Copy-number” mutations Chromosomal mutations Genome mutations Point mutations Point mutations There are four categories of point mutations: Point mutations There are four categories of point mutations: 1. transitions (e.g., A G, C T) 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) 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) 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) 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) 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. 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. Loss of function mutations in the cystic fibrosis gene “Copy-number” mutations “Copy-number” mutations • these mutations change the numbers of genetic elements. “Copy-number” mutations • these mutations change the numbers of genetic elements. • gene duplication events create new copies of genes. “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. Unequal crossing-over can generate gene duplications Unequal crossing-over can generate gene duplications Unequal crossing-over can generate gene duplications lethal? neutral? “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. and -globin gene families Chromosome 11 Chromosome 16 Timing of expression of globin genes Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba 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 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 mRNA Chromosome 3 Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba Alcohol dehydrogenase (Adh) mRNA cDNA Chromosome 2 Chromosome 3 Retrogenes may also be created • retrogenes have identical exon structures to their “progenitors” but lack introns! Example: jingwei in Drosophila yakuba Alcohol dehydrogenase (Adh) mRNA cDNA Chromosome 2 “jingwei” Chromosome 3 Whole-genome data yields data on gene families “Copy-number” mutations • transposable elements (TEs) are common. “Copy-number” mutations • transposable elements (TEs) are common. • three major classes of TEs are recognized: “Copy-number” mutations • transposable elements (TEs) are common. • three major classes of TEs are recognized: 1. insertion sequences (700 – 2600 bp) “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) “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 Chromosomal inversions lock blocks of genes together Inversions act to suppress crossing-over… inviable inviable Inversions act to suppress crossing-over… inviable inviable … and can lead to co-adapted gene complexes Chromosomal inversions in Drosophila pseudoobscura Here is a standard/arrowhead heterozygote: Here are more inversion heterzygotes: Chromosomal translocations are also common Changes in chromosome number are common Changes in chromosome number are common • in mammals, chromosome numbers range from N = 3 to N = 42. 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) 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! Muntiacus reevesi Muntiacus muntjac Muntiacus reevesi; N = 23 Muntiacus muntjac; N = 4 Genome mutations Genome mutations • polyploidization events cause the entire genome to be duplicated. Genome mutations • polyploidization events cause the entire genome to be duplicated. • polyploidy has played a major role in the evolution of plants. Genome mutations • polyploidization events cause the entire genome to be duplicated. • polyploidy has played a major role in the evolution of plants. • ancient polyploidization events have also occurred in most animal lineages. Generation of a tetraploid Where do new genes come from? Where do new genes come from? An example: the antifreeze glycoprotein (AFGP) gene in the Antarctic fish, Dissostichus mawsoni Where do new genes come from? An example: the antifreeze glycoprotein (AFGP) gene in the Antarctic fish, Dissostichus mawsoni Reference: Chen et al. 1997. Proc. Natl. Acad. Sci. USA 94: 3811 Where do new genes come from? An example: the antifreeze glycoprotein (AFGP) gene in the Antarctic fish, Dissostichus mawsoni • antifreeze proteins allow these fishes to inhabit subzero sea temperatures. Where do new genes come from? An example: the antifreeze glycoprotein (AFGP) gene in the Antarctic fish, Dissostichus mawsoni • antifreeze proteins allow these fishes to inhabit subzero sea temperatures. • act by inhibiting the growth of ice crystals. Where do new genes come from? An example: the antifreeze glycoprotein (AFGP) gene in the Antarctic fish, Dissostichus mawsoni • antifreeze proteins allow these fishes to inhabit subzero sea temperatures. • act by inhibiting the growth of ice crystals. • the AFGP gene dates to ~10 – 14 million years ago (when Antarctic ocean began to freeze over). Where do new genes come from? Step 1. Duplication of the pancreatic trypsinogen gene (6 exons long). Where do new genes come from? Step 1. Duplication of the pancreatic trypsinogen gene (6 exons long). Step 2. Deletion of exons 2 – 5. see Chen et al. 1997. Proc. Natl. Acad. Sci. USA 94: 3811 see Chen et al. 1997. Proc. Natl. Acad. Sci. USA 94: 3811 Where do new genes come from? Step 1. Duplication of the pancreatic trypsinogen gene (6 exons long). Step 2. Deletion of exons 2 – 5. Step 3. Expansion of Thr-Ala-Ala triplet 41 times at junction of exon 1. see Chen et al. 1997. Proc. Natl. Acad. Sci. USA 94: 3811 Where do new genes come from? Step 1. Duplication of the pancreatic trypsinogen gene (6 exons long). Step 2. Deletion of exons 2 – 5. Step 3. Expansion of Thr-Ala-Ala triplet 41 times at junction of exon 1. Step 4. Expression of AFGP gene in liver, release into blood. Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida • the AFGP gene in B. saida also has a Thr-Ala-Ala repeating motif! Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida • the AFGP gene in B. saida also has a Thr-Ala-Ala repeating motif! • appears to have evolved independently because: Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida • the AFGP gene in B. saida also has a Thr-Ala-Ala repeating motif! • appears to have evolved independently because: 1. flanking regions show no homology to trypsinogen Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida • the AFGP gene in B. saida also has a Thr-Ala-Ala repeating motif! • appears to have evolved independently because: 1. flanking regions show no homology to trypsinogen 2. different number and locations of introns Convergent evolution of an AFGP gene in the arctic cod, Boreogadus saida • the AFGP gene in B. saida also has a Thr-Ala-Ala repeating motif! • appears to have evolved independently because: 1. flanking regions show no homology to trypsinogen 2. different number and locations of introns 3. codons used in repeating unit are different