BIOLOGY 10
GENETICS
21 SEPT 2000
MEETING 6
GOOD MORNING!!! AFTER A CLOUDY START, IT WILL BE BEAUTIFUL!!
CONTINUING ON WITH OUR DISCUSSION OF SOME OF THE FACTORS THAT CAUSE DEVIATIONS FROM EXPECTED MENDELIAN PATTERNS…
FACTORS REQUIRED FOR CLASSIC MENDELIAN RATIOS -- CONTD
Variable Expressivity and Pleiotropy
Allelic Instability
Non-Mendelian Inheritance Patterns
Cytoplasmic Organelles (Mitochondria)
Nuclear Genes Controlling Cytoplasmic "Factors" (Snail Shell)
Genomic Imprinting, Uniparental Disomy, and The Chromosome Theory of Inheritance: Some Challenges to Basic Mendelian Assumptions
What is genomic imprinting? Epigenetic modification of a specific parental allele of a gene, or the chromosome on which it resides, in the gamete or zygote, leading to differential expression of the two alleles of the gene in somatic cells of the offspring.
Evidence For Imprinting Originated From Studies of the Whole Genome
Embryological Evidence: Formal Proof at the Level of The Genome
Nuclear transfer in Mouse Embryos
Genetic Evidence
Uniparental Disomy: The inheritance of a pair of chromosomes from only one parent
Translocations in mice
Uniparental Disomy in Humans
Cystic Fibrosis
Prader-Willi Syndrome
Prader-Willi and Angelman Syndrome
Genomic Imprinting and Incomplete Penetrance
The Interaction of Genes: The Relationship Between the Trait and Gene
Alleles Interact to Produce a New Phenotype (Chicken Combs)
Epistasis: One Gene Suppresses the Expression of Another Gene
Pea Flower Color
Seed Capsules
Dominant Epistasis
The Bombay Phenotype
CLASS PROBLEM…COLLABORATIVE EFFORT
HhAB x HhAB
Phenotypic Ratio?