1. Linked Traits and Human Genetics
Modern Genetics
Linked Traits and Human Genetics

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

4. 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

5. 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)

6. Tracking Genetic Traits
Carrier

7. 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”

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

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

10. Codominance
Example 1: IB IB IA
IAIB
IAIB IA
IAIB
IAIB

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