Human

Genetic Traits ?

ABC news – video clip

thehappyhospitalist.blogspot.com/2008_10_01_a...

http://www.telegraph.co.uk/news/worldnews/asia/indonesia/tree-man/

Dominant and Recessive TraitsDominant traits are seen in the phenotype for both Heterozygous (Tt) andHomozygous (TT) genotypes.

Dominant Examples:• Tongue-roller• Freckles• High blood pressure• Dwarfism• Six fingers• Baldness (males)• Dimples

Recessive traits are seen in the phenotype ONLY

When a person has a Homozygous (tt) genotype.

Genetic DiseasesDominant (TT or Tt)• Huntington’s

Recessive (tt)• Tay-Sachs• PKU• Cystic Fibrosis• Sickle-cell Anemia

Sex-Linked Recessive (XrY) or (Xr Xr) • Hemophilia• Color blindness

Other Inherited DiseasesDown Syndrome

(3 copies of chromosome 21)

Nondisjunction

Examples of Diseases which are NOT Inherited

Infectious Diseases• Chickenpox• Flu• Strep throat• Food poisoning

Cancer• Some cancers are due MOSTLY to environmental exposure• Some cancers have a genetic risk factor

Diet• Some diseases are caused by a lack of nutrients like vitamin C