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22 terms

AP Biology: Heredity

AP Exam 2012
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Law of Segregation
During formation of gametes, 2 traits carried by each parent separate: Monohybrid cross
Monohybrid cross
Phenotype ratio: 3:1, Genotype ratio: 1:2:1 (Aa x Aa)
Law of independent assortment
Applies in a cross between 2 individuals hybrid for 2+traits Not on the same chromosome
Dihybrid Cross
Cross between 2 individuals hybrid for 2 different traits: AaBb x AaBb, can have AB Ab aB ab: 9:3:3:1
Incomplete Dominance
Dominance characterized by blending: Eg. White + Red = pink flower
Codominance
Dominance where both traits show: eg. Blood groups (MN) in humans
Multiple Alleles
When there are more than 2 allelic forms of a gene: eg. A, B, AB, O blood types
Pleiotropy
Ability of 1 gene to affect an organism in several ways
Epistasis
2 separate genes control 1 trait, but 1 gene masks the expression of the other gene
Polygenic
Traits like this result from a blending of several separate genes
Sex-influenced trait
Inheritance influenced by sex of individual carrying the traits
Linked genes
Genes on the same chromosome
Sex-linked
Traits carried on the X chromosome
Autosome
Chromosome that is not X or Y
Chiasma
Site of chromosome crossover
Mutations
Any changes in the genome, can be gene mutations (changes in sequence) or chromosome mutations
Deletion
Chromosomal aberration of fragment lost
Inversion
When a chromosomal fragment reattaches in reverse direction
Translocation
When a fragment of a chromosome is attached to a non-homologous chromosome
Polyploidy
When there are extra chromosomes
Nondisjunction
Error in meiosis where homologous chromosomes fail to separate
Aneuploidy
Any abnormal chromosome number