LIFE 120 Lecture Notes - Lecture 28: Martha Chase, Maurice Wilkins, X-Ray Crystallography
Document Summary
Chapter 12, 13 chromosomes lecture 1 (with clicker questions in red) Alternations of chromosome number or structure cause genetic disorders: chromosomal alterations. Lead to miscarriages or developmental disorders: nondisjunction. Homologous chromosomes do not separate normally during meiosis. One gamete receives two/other no chromosome: aneuploidy - results from nondisjunction. Abnormal number of chromosomes in a zygote. Trisomy of ch 21 causes down syndrome: nondisjunction & aneuploidy. Occurs during meiosis i or meiosis ii with different results. 1 trisomic & 1 monosomic gamete if meiosis ii. How linkages affect inheritance: thomas hunt morgan did experiments with fruit flies to see how linkage affects inheritance of two characters, morgan crossed flies that differed in traits of body color and wing size. Morgan found that body color and wing size are usually inherited together in specific combinations (parental phenotypes) He noted that these genes do not assort independently, and reasoned that they were on the same chromosome.
