Inherritance Notes Flashcards
Recessive hereditary
Traits that require two recessive alleles to be expressed
Most genetic disorders are caused by recessive alleles
Many of theses alleles are rare or in certain ethnic groups
What are some examples of recessive hereditary
Tay-Sachs disease
Phenylketonuria
Cystic fibrosis
Albinism
Complex patterns of inheritance
Most traits are inherited in a more complex manner than simple dominance or recessive
Incomplete dominance
Heterozygous individuals display a phenotype that is intermediate between dominant and recessive
What is an example of incomplete dominance
Ex: snapdragons
RR red flowers
RR’ pink flowers (incomplete dominance)
R’R’ white flowers
Multiple alleles
Each person has only two alleles one from each parent but there are more than two alleles within the population
Multiple alleles example
Blood types- 3 alleles IA, IB and i IAIA type A blood IAi type A blood IBIB type B blood IBi type B blood IAIB type ab blood ii type o blood
Sex-linked inheritance
Genes that are on the X or Y chromosome
Ex:color blindness
Two examples of sex linked inheritance
Hemophilia
Fragile X-syndrome
Polygenic inheritance
Traits that are controlled by more than one gene. If all genes are dominant then one extreme is the phenotype. If all genes are recessive then the other extreme is the phenotype. If all genes are heterozygous then the phenotype is intermediate.
Ex: hair and eye color
Aneuploidy
Changes in chromosome number
Either too many or not enough chromosomes. Caused by no disjunction failure of chromosomes to separate accurately during meiosis.
Examples: Down syndrome and turners syndrome
Dominant hereditary
Traits that require one dominant allele to be expressed. Genetic disorders caused by dominant alleles
Dwarfism
Huntington’s disease
