Variation in Chromosome structure and number.pptx

Variation in Chromosome structure and number.pptx

• 1.
  Rashmi M G Variationin Chromosome structure and number 1. Cytogenetics 2. Importance of karyotyping 3. Chromosome structure 4. Variation in chromosome number 5. Variation in chromosome structure
• 2.
  Rashmi M G Introduction Cytogenetics: •Study of structure, function and abnormalities of chromosomes • Analysis of stained chromosomes Chromosome= DNA+Protein Found in Nucleus in Eukaryotic cells Human Karyotype- Number , sizes, shapes of metaphase chromosome= Karyotype/ Karyogram Karyotype consisting photo/ diagram of all metaphasic chromosomes arranged in homologous pairs according to decreasing length and position of Centromere= Idiogram
• 3.
  Rashmi M G Importanceof karyotyping • Determination of chromosome size • Determination of chromosome number • Features of sex chromosomes • Centromere position • Nucleolar organizer position • Heterochromatin pattern • Secondary constriction • Banding pattern • Chromosomal abnormalities Human Karyotype showing abnormal chromosomes (blue) resulting from a reciprocal exchange of parts of 2 non homologous chromosomes Source: Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.463
• 4.
  Rashmi M G Chromosomestructure Source: Benjamin A Pierce, Genetics, A conceptual approach, Page no. 21
• 5.
  Rashmi M G Chromosomestructure Source: Benjamin A Pierce, Genetics, A conceptual approach, Page no. 21,22
• 6.
  Rashmi M G Disclaimer!!! Theupcoming slides contains some of the explicit contents which may cause discomfortness. The contents are intended for education purpose, to facilitate discussion, analysis and to illustrate the specific concepts within an academic context. The inclusion of these contents does not endorse or promote the material itself but serves to enhance understanding of the subject matter
• 7.
  Rashmi M G Variationin chromosome number Organism 1 Set chromosome= Monoploid (X) 2 Sets chromosomes= Diploid (2X) More than 2 sets= Polyploid (>2X) Number of sets= “Ploidy” Difference between Monoploid and haploid: Haploid value(n) Monoploid (X) Number of chromosome present in gamete Number of chromosome in single set Ex. Humans Diploid (2n) 2 Sets of chromosome (Paternal and maternal) Monoploid, Haploid value= (X=n=23) Ex: Hexaploid bread wheat Hexaploid (6n) 6 sets of chromosome Monoploid= X=7 Haploid value=n= 21
• 8.
  Rashmi M G Polyploidy Autopolyploidy Multiplicationof same genome May be, Triploid (3X) Tetraploid (4X) Pentaploid (5X) Hexaploid (6X) Allopolyploidy Crossing different species and doubling chromosomes of hybrid Multiplication of different genome/ hybrid genome May be, Tetraploid (3X) Hexaploid (6X) Source: Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.203
• 9.
  Rashmi M G Source:Benjamin A Pierce, Genetics, A conceptual approach, Page no. 254 Source: Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.204
• 10.
  Rashmi M G Aneuploidy •Lossor gain of one/ few chromosomes •Caused by non disjunction during mitosis or meiosis •Non disjunction occurs spontaneously •In meiotic non disjunction, chromosome may fail to disjoin at either, 1st or 2nd meiotic division (most frequently occurs in 1st meiotic division) Source: Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.199
• 11.
  Rashmi M G Source:Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.477
• 12.
  Rashmi M G Aneuploidyin Humans Autosomal Aneuploidy Ex. 1. Down’s Syndrome 2. Edward’s Syndrome 3. Patau’s Syndrome Allosomal Aneuploidy Ex. 1. Turner’s Syndrome 2. Klinefelter Syndrome Source: Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.478
• 13.
  Rashmi M G AutosomalAneuploidy Examples of Trisomy 1. Down’s Syndrome (47,+21) 2. Trisomy in Jimson Weed 3. Edward’s Syndrome (47,+18) 4. Patau’s Syndrome (47,+13)
• 14.
  Rashmi M G Source:Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.200,201
• 15.
  Rashmi M G Source:Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.281
• 16.
  Rashmi M G AllosomalAneuploidy Examples: 1. Turner Syndrome (45, X) 2. Klinefelter Syndrome (47, XXY)
• 17.
  Rashmi M G Source:Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.348
• 18.
  Rashmi M G Variationin Chromosome structure Deletion Loss of segment of chromosome Types: Terminal Interstitial Duplication Occurrence of segment of chromosome in 2/ more copies per genome Types: Tandem Reverse Inversion Break of segment and rotated before rejoining Types: Pericentric Paracentric Heterozygous Homozygous Translocation 2 non homologous chromosome exchanges and rearrangement of segment happens Types: Reciprocal Non reciprocal
• 19.
  Rashmi M G Source:Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.207
• 20.
  Rashmi M G Deletion Deletionstarts where breaks occur in chromosomes Breaks can be induced by agents like, Heat, Radiation (Ionizing Radiation), Viruses, Chemicals and transposable elements Examples: 1. Cri Du Chat syndrome (Deletion of part of short arm of chromosome 5) 2. Prader Willi syndrome (Deletion of part of long arm of chromosome 15) Source: Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.467
• 21.
  Rashmi M G Duplication Doublingof a segment of a chromosome. Example: Bar mutant on X chromosome of Drosophila melanogaster Source: Peter J Russell, iGenetics A molecular approach, 3rd edition, Page no.468
• 22.
  Rashmi M G Inversion Asegment of Chromosome is excised and then reintegrated at an orientation 180 degrees from the original orientation It reveals about the evolution of humans Source: Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.212
• 23.
  Rashmi M G Translocation Themovement of chromosomal segment to a new location in the genome Examples: 1. Familial Down syndrome Source: Klug cummins, Spencer, Palladino (2012), Concepts of Genetics, Pearson Publication, 10th Edition, Page no.214