1. Human Chromosomes and Genes Sanjaya Adikari Department of Anatomy

2. DNA DNA is the genetic material DNA is organized into chromosomes

3. Chromosomes DNA histone proteins non-histone proteins chromatin chromosome

5. Chromosomes…. cell division chromatids short arm (p) long arm (q) centromere telomere

7. Autosomes and sex chromosomes Total of 46 chromosomes 23 pairs of chromosomes 22 pairs of autosomes 1 pair of sex chromosomes, XX or XY

8. Karyotype Chromosome constitution of a cell Normal male46,XY Normal female46,XX

9. Karyotyping Karyograph

10. Homologous pair Karyograph

11. Haploid and diploid haploid diploid 123456

12. Somatic cell haploid gametes in meiosis,

13. Genes Gene is a sequence of DNA coding for a polypeptide

14. Exon 1 Intron 1 Exon 2 Intron 2 Intron 3 Exon 3 Exon 4 Gene genes non coding regions chromosome

15. Locus and alleles A A Genes residing at the same level of the homologous pair of chromosomes are called alleles Homologous pair Locus Alleles are in the same locus

16. Homozygous and heterozygous AA aa Homozygous Aa AB Heterozygous

17. Recessive and dominant characters Tt Dominant characters are expressed in the heterozygote * Recessive characters are expressed only in the homozygote # * heterozygote=person with heterozygous genotype # homozygote=person with homozygous genotype

18. TT => tall Tt => tall tt => short ‘Tall’ is the dominant character ‘Short’ is the recessive character

19. Genetic polymorphism Locus A A Blood groups ABO AA AO BB BO AB OO group-A group- B group-AB group-O

20. References Emery’s Elements of Medical genetics. Robert F. Mueller and Ian D. Young Medical Library Class No. 616.042 Medical Genetics: An illustrated outline. Andrew Read Medical Library Class No. 616.042 Web sites http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chromosomes.html http://www.csu.edu.au/faculty/health/biomed/subjects/molbol/DNAstruc.htm http://gslc.genetics.utah.edu/units/disorders/karyotype/karyotype.cfm http://homepages.which.net/~gk.sherman/baaaaabz.htm http://www.eurekah.com/abstract.php?chapid=1777&bookid=118&catid=19