Genetic disorders 1


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Genetic Disorders (No 1)

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Genetic disorders 1

  1. 2. GENETIC DISORDERS (Introduction) <ul><li>Dr. Shahab Riaz </li></ul>
  2. 4. Chromosome: <ul><li>Greek ( chroma , color) and ( soma , body) bcz strongly stained by particular  dyes </li></ul><ul><li>organized structure of  DNA  and  protein , found in  cells </li></ul><ul><li>single piece of coiled DNA containing many  genes ,  regulatory elements  and other  nucleotide sequences </li></ul><ul><li>In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called  chromatin </li></ul><ul><li>very long DNA molecules to fit into the  cell nucleus </li></ul>
  3. 6. Gene: <ul><li>basic unit of  heredity  in a living  organism </li></ul><ul><li>information to build and maintain the  cells  and pass genetic  traits  to offsprings </li></ul><ul><li>In general terms, a gene is a segment of  nucleic acid  that, taken as a whole, specifies a trait </li></ul>
  4. 8. <ul><li>Gregor Mendel </li></ul>
  5. 9. History: <ul><li>Gregor Mendel  (1822–1884) a priest  and scientist </li></ul><ul><li>In 1860s, studied inheritance in  pea plants father of  genetics  for his study of the  inheritance  of certain traits  in  pea  plants </li></ul><ul><li>hypothesized  a factor that conveys traits from parent to offspring </li></ul><ul><li>over 10 years of his life on one experiment </li></ul><ul><li>showed that the inheritance of these traits follows particular  laws </li></ul><ul><li>Mendel's work was not recognized until the turn of the 20th century </li></ul><ul><li>Didn’t use the term  gene , explained results in terms of inherited characteristics </li></ul><ul><li>dominant  and  recessive  traits, the distinction between a  heterozygote and  homozygote ,  genotype  and  phenotype </li></ul>
  6. 10. Deoxyribonucleic acid (DNA): <ul><li>nucleic acid   </li></ul><ul><li>genetic  instructions & the long-term storage of  information </li></ul><ul><li>blueprints , or a  code for development and functioning </li></ul><ul><li>Construction of cellular proteins  and  RNA  molecules </li></ul><ul><li>DNA segments that carry this genetic information are called  genes </li></ul>
  7. 11. DNA Structure: <ul><li>two long  polymers  of simple units called  nucleotides </li></ul><ul><li>backbones made of  sugars  and  phosphate  groups joined by  ester  bonds </li></ul><ul><li>two strands are anti-parallel </li></ul><ul><li>Attached to each sugar is one of four types of molecules called  bases </li></ul><ul><li>sequence of these four bases along the backbone that encodes information </li></ul>
  8. 15. Messenger ribonucleic acid (mRNA) : <ul><li>molecule of  RNA  encoding a chemical &quot;blueprint&quot; for a  protein  product </li></ul><ul><li>mRNA is  transcribed  from a  DNA  template </li></ul><ul><li>carries coding information to the sites of  protein synthesis : the ” ribosomes ” on RER </li></ul><ul><li>the nucleic acid polymer is  translated  into a polymer of  amino acids : a “ protein” </li></ul><ul><li>In mRNA as in DNA, sequence of  nucleotides  arranged into  codons  consisting of three bases each </li></ul><ul><li>Each codon encodes for a specific  amino acid </li></ul><ul><li>stop codons  terminate protein synthesis </li></ul>
  9. 16. <ul><li>Codon: </li></ul><ul><li>Base triplet in mRNA transcribed by DNA </li></ul><ul><li>If the base triplet in the DNA sequence is GCT Then </li></ul><ul><li>corresponding codon on the mRNA strand will be CGA </li></ul><ul><li>Transfer RNA (tRNA): </li></ul><ul><li>mediates recognition of the codon </li></ul><ul><li>provides the corresponding amino acid </li></ul><ul><li>Ribosomal RNA (rRNA): </li></ul><ul><li>central component of the ribosome's protein manufacturing machinery </li></ul><ul><li>Anti-Codon: </li></ul><ul><li>sequence of three adjacent nucleotides in transfer RNA </li></ul><ul><li>binds to a corresponding codon in messenger RNA </li></ul><ul><li>designates a specific amino acid during protein synthesis </li></ul>
  10. 19. <ul><li>20 Amino Acids In Human Protein: Table of DNA Base Triplets, RNA Codons & Anticodons </li></ul>
  11. 20. GENETICS: <ul><li>Ancient Greek   genetikos , “genitive” and that from  genesis , “origin” </li></ul><ul><li>science  of  heredity  and  variation  in living organisms </li></ul><ul><li>living things inherit traits from their parents  prehistoric  times  improve crop plants and animals through selective breeding </li></ul><ul><li>Modern genetics basis by Gregor Mendel </li></ul>
  12. 21. <ul><li>Genome: </li></ul><ul><li>full set of chromosomes  or genes in a  gamete </li></ul><ul><li>So a regular  somatic cell  contains two full sets of genomes </li></ul><ul><li>In  haploid   organisms , including  bacteria ,  viruses , and  mitochondria , a cell contains only a single set of the genome </li></ul><ul><li>Genomics: </li></ul><ul><li>study of the  genomes  of organisms </li></ul><ul><li>entire  DNA sequence  of organisms and fine-scale  genetic mapping  efforts </li></ul><ul><li>Research of single genes does not fall into the definition of genomics </li></ul>
  13. 22. Importance of Genetics <ul><li>Life time frequency  670/1000 </li></ul><ul><li>Classic genetic diseases + CVS diseases and cancer </li></ul><ul><li>Some diseases have both environmental + genetic role (atherosclerosis / HTN) </li></ul><ul><li>In medical practice  Iceberg of Genetic diseases  less severe </li></ul><ul><li>50% of spontaneous abortions  gross chromosomal abnormalities </li></ul>
  14. 23. Importance of Genetics <ul><li>100,000 previously thought but actually approx 30,000 </li></ul><ul><li>Different combinations  > 100,000 proteins </li></ul><ul><li>Fully formed proteins can be sliced/stitched  > peptides than expected </li></ul><ul><li>Avoiding intra-uterine diseases </li></ul><ul><li>Thalassemia  inter-marriages </li></ul><ul><li>Treatments of cancer  Genetic Level </li></ul>
  15. 24. Interesting Fact <ul><li>99.9% of genomic DNA sequence of any two humans is the same </li></ul><ul><li>0.1% rest of the genome  accounts for the differences in features  approx. 3 million base pairs </li></ul>
  16. 25. Genetic Advancements
  17. 26. Molecular Basis of Human Diseases <ul><li>Two general strategies used to isolate involved genes </li></ul><ul><li>Functional Cloning or Classical Approach: </li></ul><ul><li>Abnormal gene product / protein known </li></ul><ul><li>Isolate normal gene and clone </li></ul><ul><li>Determine molecular changes causing the disorder </li></ul><ul><li>Positional Cloning or Candidate Gene Approach: </li></ul><ul><li>In some diseases, multiple genes involved or no clue of defective product </li></ul><ul><li>Ignores the phenotype or protein product </li></ul><ul><li>Instead mapping disease phenotype to specific chromosome location </li></ul><ul><li>Marker genes identified  Close proximity to disease locus </li></ul><ul><li>Localized narrow limits  clone DNA from relevant site in vitro </li></ul><ul><li>Identification of protein  aberrant protein encoded by mutant genes </li></ul>
  18. 28. Genetic Engineering <ul><li>Production of human biologically active agents </li></ul><ul><li>Recombinant DNA technology </li></ul><ul><li>Improving crop technology </li></ul><ul><li>manufacture of synthetic human  insulin  through the use of modified  bacteria </li></ul><ul><li>manufacture of  erythropoietin  in hamster  ovary cells </li></ul><ul><li>Growth hormone </li></ul><ul><li>GM-CSF & G-CSF </li></ul>
  19. 29. Genetic Engineering <ul><li>Isolation of the genes of interest </li></ul><ul><li>Insertion of the genes into a transfer  vector </li></ul><ul><li>Transfer of the vector to the organism to be modified </li></ul><ul><li>Transformation of the cells of the organism </li></ul><ul><li>5. Selection of the genetically modified organism (GMO) from those that have not been successfully modified </li></ul>
  20. 31. Gene Therapy <ul><li>insertion of  genes  into an individual's  cells  and  tissues  to treat a  disease </li></ul><ul><li>hereditary disease  in which a deleterious  mutant   allele  is replaced with a functional one </li></ul><ul><li>Although the technology is still in its infancy, it has been used with some success. </li></ul><ul><li>Appropriate Vectors ??? </li></ul><ul><li>Random Insertion in other Cells </li></ul>