Mendel Extension Flashcards
Late Onset Definition
A genetic disorder whose symptoms appear later in life (Huntingtons Disease)
Late Onset Violation
Immediate expression of genotype bc the phenotype doesn’t appear to later in life (Appears to follow Mendelian inheritance , delayed expression can mask carrier status)
Variable Expressivity Definition
The same type of genotype results in varying phenotypic severity. ( Marfan, some get long limbs, some get heart problems)
Variable Expressivity Violation
Uniformity of expression (offspring may show range of phenotypes despite having same genotype)
Incomplete Penetrance Definition
Not all individuals with a genotype express the associated phenotype (polydactyly)
Incomplete Penetrance Violation
Predictable phenotype from genotypes( unexpected phenotypical ratios occur)
Environmental Effects Definition
The environment influences gene expression (Siamese cat)
Environmental Effects Violation
Mendel’s idea that genes alone determine phenotype (phenotypical ratios are inflicted by external factors)
Norms of Reaction Definition
A range of phenotypes produced by a genotype in different environments (flower depending on pH) (considered a range of responses)
Norms of Reactions Violation
Fixed genotype=fixed phenotype (offspring may not fit expected ratio due to environmental influences)
Sex Linkage Definition
Genes located in sex chromosomes (color blindness)
Sex Linkage Violation
Equal inheritance of traits by males and females ( Males(XY) and Females (XX) show different inheritance patterns)
Sex Influenced Definition
Traits influenced by sex hormones (male pattern baldness)
Sex Influenced Violation
Trait expression is not always the same in both sexes ( a trait may behave as dominant in one sex and recessive in another)
Sex Limited Definition
Traits only expressed in one sex, despite both carrying the gene. (milk production)
Sex Limited Violation
All genotypes are equally expressed in both sexes (Certain phenotypes will never appear in one sex)
Independent Dominance/ Codominance Definition
ID: Heterozygotes show a blend of the two parental
C: Both alleles are expressed equally
Independent Dominance/ Codominance Violations
Strict dominance and recessiveness (Ratios are not standard Mendelian( 1:2:1 instead of 3:1)
Imprinting Definition
Genes are expressed differently depending on whether they were inherited from the mother or father
Imprinting Violation
Equal contribution of parental alleles to offspring (Offspring phenotypes depend on which parent contributed the allele)
Complementation Definition
Occurs when two recessive alleles in different genes produce the same phenotypes. STRICTLY AN F1 PHENOMENON (two deaf parents)
Simple Genetic Interaction Definition
2 genes effect 1 trait (pepper colors)
Duplicate Genetic Interaction Definition
Occurs when two different genes can produce the same phenotype as a mutant
Ex. 9:6:1 and 10:3:3
Epistasis Definition
When the phenotype from one gene masks then phenotype of the second (albanism)
