Biology 1202B Lecture Notes - Lecture 19: Ovulation, Methylation, Ivacaftor
25 Mar 2016
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Balanced: not missing any genetic material, it may be somewhere else in the individual but it is still there , less phenotypic consequences. Most genes are present as 2 copies and expressed from both. Abnormalities lead to an increase/decrease in copy and thus expression. Imprinted regions are expected to only have one copy of a gene and only one expressed. >the phenotype of a trisomy depends on the genes on the extra chromosome. Monosomies = lethal (if you"re missing any one of your chromosomes) Trisomy one is the least lethal out of trisomies. Failure of a pair of chromosomes to disjoin during one of the meiotic divisions. >different outcomes when the nondisjunction is in meiosis i or ii. >the older the egg, the greater the chance of nondisjunction. >egg completes meiosis i just prior to ovulation. Individuals who are homozygous or heterozygous for mutant a allele will have the disease. A single copy of mutant allele is sufficient.
