Linked Traits and Human Genetics Modern Genetics Linked Traits and Human Genetics

Chromosomes and Inheritance Chromosome Theory of Inheritance – states that genes are located on chromosomes and these chromosomes are passed from parent to child

Sex-linked traits Many species have sex chromosomes that determine if you are male or female, humans do also Any gene located on either sex chromosome (X or Y) is called a Sex-linked Trait

Tracking Genetic Traits Since geneticists can’t control people having children (that would be immoral….and creepy) they must analyze patterns Pedigree – a family tree that records and traces traits (phenotypes)

Tracking Genetic Traits Carrier

Sample Problem The offspring would look something like this Why are all the offspring tall? Dominant – an allele that “masked” or covers up another allele Recessive – an allele that does not show up in a heterozygous individual, it is “masked”

Codominance Codominance – when a heterozygous individual expresses both traits equally, one allele is not completely dominant

Codominance Example 1: Blood type has 3 alleles IA - Dominant IB – Dominant i – Recessive

Codominance Example 1: IB IB IA IAIB IAIB IA IAIB IAIB

Codominance Example 2: i i IA IAi IAi i ii ii