Identical Twins


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Identical Twins

  2. 2. THESIS The distinct differences found at the genetic level in twins are causing scientists to question the idea of “identical”.
  3. 3. TYPES OF IDENTICAL TWINS Dichorionic, Diamniotic Monochorionic, Diamniotic Monochorionic, Monoamniotic
  4. 4. DICHORIONIC, DIAMNIOTIC TWINS Zygote split in the first two days after fertilization Develop in different placentas and amniotic sacs Only occur 20-30% of the time
  5. 5. MONOCHORIONIC, DIAMNIOTIC TWINS Zygote splits after the first two days of fertilization Grow in the same placenta and different amniotic sacs Occur most often
  6. 6. MONOCHORIONIC, MONOAMNIOTIC TWINS Grow in the same placenta and amniotic sac Only occur about 1% of the time
  7. 7. WHAT IS IDENTICAL? To be considered an identical twin:  have to come from the same zygote  have same blood type  have to be the same sex  have the same hair color
  8. 8. JONATHAN MILL Study was used to determine how genes are activated differently in identical twins  studied the genome of 22 pairs of identical twins  did have identical DNA, but they had certain differences in chemical markings  chemical markings do not alter the DNA sequence, but they do leave marks on genes
  9. 9. NATURE VS. NURTURE Genes = Nature Environment = Nurture Manel Esteller  studied 49 pairs of identical twins  determine that epigenetic analysis could differentiate between twins in a criminal case
  10. 10. EVERY BRAIN IS UNIQUE Life experience influences brain differences  change the strength of connections between certain neurons Jumping Genes  genes that paste copies of themselves into the genome  causes cells to act differently  can lead to differences in cognitive abilities, personality traits, and susceptibility to neurological problems
  11. 11. TESTS USED TO IDENTIFY DIFFERENCES High resolution cameras Fingerprinting Iris scanners
  12. 12. DIFFERENCES DISCOVERED Gene Expression Environmental Factors
  13. 13. GENE EXPRESSION Although they did possess nearly identical genomes, closer study revealed they often differed in the number of copies of individual gene segments. For instance, one twin might be missing a segment, or possess more copies of that segment than the other twin They can develop different disorders and illnesses
  14. 14. ENVIRONMENTAL FACTORS Fingerprints  caused by the different conditions experienced by the fetuses in the womb Smoking, drugs, and alcohol Sun Personality Differences  caused by different chemicals in the body that are affected by a person’s lifestyle choices
  15. 15. WORKS CITED QrgSHX25vpBlYsrqHgzYzdm1lzSz4/natgeotwins01.jpg A/S5Z3oYGfMhI/AAAAAAAAB2U/52NonF1w66Q/s400/DichorionicDiamniotic.jpg eimerGenes2689161031.jpg