1. A Seminar on CHROMOSOMES Presented ByK. GANAPATHI RAO (13031D6003) Presence of Miss. CH SILPA CHAKRA (HOD) CNST-JNTUH IST

2. OUTLINE Introduction. Chromosome. Types Of Chromosomes. Cell Division. Meiosis And Fertilisation. Human Chromosomal Abnormalities. Chromosomes Structure. Structural Chromosomes Disorders. 3. CELL Basic unit of building the body 4. Chromosomes In Different Cells PROKARYOTESEUKARYOTESsingle chromosome plus plasmidsmany chromosomescircular chromosomelinear chromosomesmade only of DNAmade of chromatin, a nucleoprotein (DNA coiled around histone proteins)found in cytoplasmfound in a nucleuscopies its chromosome and divides copies chromosomes, then the cell immediately afterwards grows, then goes through mitosis to organise chromosomes in two equal groups 5. Chromosome Chromosomes are the rod-shaped, filamentous bodies present in the nucleus, which become visible during cell division. They are the carriers of the gene or unit of heredity. Chromosome are not visible in active nucleus due to their high water content, but are clearly seen during cell division. Chromosomes were first described by Strausberger in 1875. The term Chromosome, however was first used by Waldeyer in 1888.Chromo=colour Soma=body Chromosome 6. CHROMOSOME 7. NUCLEOSOMES30 NM SOLENOID/ CHROMATIN FIBER CHROMATIN FIBER LOOPS 8. No of chromosomes Normally, all the individuals of a species have the same number of chromosomes. Presence of a whole sets of chromosomes is called euploidy. When a change in the chromosome number does not involve entire sets of chromosomes, but only a few of the chromosomes - is Aneuploidy. Gametes normally contain only one set of chromosome this number is called Haploid Somatic cells usually contain two sets of chromosome 2n - Diploid 3n triploid 4n tetraploid 9. No of chromosomes Round worm Onion Tomato2 16 24 10. Chromosome Size In contrast to other cell organelles, the size of chromosomes shows a remarkable variation depending upon the stages of cell division. Interphase: chromosome are longest & thinnest Prophase: there is a progressive decrease in their length accompanied with an increase in thickness Anaphase: chromosomes are smallest. Metaphase: Chromosomes are the most easily observed and studied during metaphase when they are very thick, quite short and well spread in the cell. 11. Can distinguish chromosomes by painting using DNA hybridization + fluorescent probes 12. Types of Chromosomes Autosomes Paired chromosomes with the same length, shape, centromere location, and genes Any chromosome other than a sex chromosome Determine size, colour, hair of a body. Sex chromosomes Members of a pair of chromosomes that differ between males and femalesHOMOGAMETIC SEXHETEROGAMETIC SEXSEX DETERMINATIONFemale XXMale XYPresence of Y-chromosome = maleness (mammals and fish) Presence of second X-chromosome = femaleness (Drosophila, the fruit fly)Male ZZFemale ZWBirds, amphibians, reptiles, butterflies, moths.Female XXMale XoGrasshoppers 13. CELL DIVISIONS Meiosis: A special type of cell division Used to make sex cells Meiosis halves the numbers of chromosomes Meiosis picks one chromosome from each pair at random and places them in a sex cell. This results in enormous variation amongst the sex cells Mitosis: Normal cell division Chromosomes are duplicated and distributed equally 14. Meiosis and fertilisation MotherFather23 pairs of chromosomes23 pairs of chromosomesMeiosis23 unpaired chromosomes23 unpaired chromosomes23 unpaired chromosomes Fertilisation 23 pairs of chromosomesChild23 unpaired chromosomes 15. The inheritance of genderIs it going to be a boy or a girl? 16. The inheritance of gender MotherFatherXXXYXXXX FertilisationYXXXXYXXXXYYPossible childrenChance of a girl 50% Chance of a boy 50% 17. Human chromosomal abnormalities Numerical (Chromosomal Disorders) Trisomy = 3 copies of a single chromosome 47 Monosomy = 1 copy of a single chromosome 45 Triploidy = 3N Tetraploidy = 4NStructural (Chromosomal Disorders) Deletion Duplication Translocation (involves 2 chromosomes) 18. Causes of Chromosomal Disorders Ionising radiation, autoimmunity, virus infections and chemical toxins in the pathogenesis of certain disorders. 19. Some Numerical Disorders XXY = Klinefelters syndrome male Feminine character. Tall, Normal Intelligence. XXX = Trisomy X female Produce healthy female. XYY = Jacobs syndrome male Height, more active. Slightly learning disability. Normal intelligence. X/XO = Turner syndrome female Webbed neck. Short height. Immature females. 20. Chromosomes Structure Centromere p arm q arm Telomeres 21. ArmRegion2p 11Band2 1 11q 3Chromosome 173 2 1 2 1 5 4 3 2 1 1 222Subband43 1 2 3 1 2, 3 4 1 2 317 q 1 1 . 2 22. Chromosome Structure AbnormalitiesTranslocationDeletionDerivative chromosomeInversionInsertionIsochromosomeRing chromosome 23. Some Structural Disorders Cri-Du-Chat Syndrome #5q Deletion Moon-shaped face, Heart disease Mentally retarded, Malformed larynx Normal lifespan Aniridia-Wilms Tumor Syndrome #11p Deletion Mentally retarded, Growth retarded Blindness, Tumors on kidneys Short lifespan Thirteen Q Deletion Syndrome Mentally retarded, Deformed face No thumbs, Heart disease Short lifespan 24. Some Structural Disorders Prader-Willi Syndrome #15q Deletion Small bird-like head, Mentally retarded Respiratory problems Obesity, Short lifespan Eighteen Q Deletion Syndrome #18q Deletion Mentally retarded, Heart disease Abnormal hands and feet Large eyes, Large ears Normal lifespan Burkitt Lymphoma Translocation of the Myc gene on chromosome 8 Translocated Myc genes dont function properly Leads to cancer of the lymph nodes 25. Some Structural Disorders Cat-Eye Syndrome #22q Deletion Fused fingers and toes Mentally retarded, Small jaw Heart problems, Normal lifespan Pataus Trisomy Syndrome #13 Trisomy Nondisjunction Small head, Small or missing eyes Heart defects, Extra fingers Abnormal genitalia, Mentally retarded, Cleft palate Most die a few weeks after birth Four-Ring Syndrome #4 Inversion Cleft palate, Club feet Testes dont descend Short lifespan 26. Videos 1. What Is A Chromosome. 2. How Dna Is Packaged (Advanced). 3. Chromosome Disorder Outreach Video. 4. Unique Children With Rare Chromosome Disorders. 27. REFRENCE Human Chromosomes by Orlando J. Miller, Chromosome biology by R. Appels, http://www.chromodisorder.org/CDO/ http://www.genome.gov/26524120 http://www.youtube.com/watch?v=zf7tbymrv9 o http://www.johnkyrk.com/chromosomestructu re.html