Genotype Phenotype
Problems:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1. Incomplete dominance (snapdragons)
One gene, two alleles, three phenotypes
Genotypic ratios equal phenotypic ratios
 
2. Co-dominance (sickle cell anemia)
Analysis of proteins by gel electrophoresis
Genotype determination from protein patterns
Homozygosity versus heterozygosity
Screens for heterozygosity
Paternity testing
 
3. Multiple alleles (ABO blood types)
Two gene hypothesis versus one gene multiple alleles
Genotype determination
 
4. Multiple alleles (hypothetical birds)
Multiple genes versus multiple alleles
Allelic series
Genotypes from phenotypic ratios
 
5. Two traits, three genes, incomplete dominance and epistasis
Breakdown of complex data
Phenotypic ratios to predict number of genes and relationships between genes
 
6. Epistasis (Bombay phenotype, humans)
Genotypes
Discrepancy in pedigrees
Epistatic gene
Southern analysis
 
7. Homozygous lethality (Curled ear in cats)
Spontaneous dominant mutation
Homozygous dominant never found
2:1 ratios
Achondroplasia (human example)