Final- 14 Flashcards
What is a test cross
Crossing the organism in question (all possibilities) with an organism that is homozygous recessive
Ways in which alleles are not completely dominant or recessive
- Complete dominance
- Incomplete dominance
- Codominance
Complete dominance
Phenotypes of heterozygote and homozygote are identical
Incomplete dominance
Phenotype is somewhere in between
red and white flowers give pink
Codominance
2 alleles affect the phenotype in separate distinguishable ways
(AB blood type)
Multiple alleles
most genes exist in populations in more than two forms
ABO blood group, A (adds A carbohydrate), B (adds B carbohydrate), AB, and O (adds neither)
Pleiotrophy
most genes have multiple phenotypic effects (ex: cystic fiborsis, sickle cell)
Responsible for multiple symptoms of certain hereditary diseases
Epistasis
Gene at one locus alters the phenotypic expression of a gene at another locus (ex: coat color in Laborador retrievers, Bb is color pigment, C or c determines if whether or not the pigement will show)
Pedigree analysis
Family tree of genetic traits
Across generations, inheritanace patterns
Recessively inherited disorders
Carriers are heterozygotes, usually rare
Cystic fibrosis and sickle cell
Cystic fibrosis
defective or absent chloride transport. Mucus buildup, abnormal absorption of nutrients is phenotypic expression
Sickle cell
substitution of single amino acid. Weakness, pain, organ damage, paralysis is phenotypic expression
When are recessive disorders common
In same blood marriages
Two dominantly inherited disorders
Achondroplasia, dwarfism
Huntingtons disease, degenterative disease of the nervous system
Rare because of natural selection
