27.2 Human Traits Survey Complete Dominance Incomplete Dominance X-Linked Traits

Types of Traits Physical traits: hair, eyes, skin, features, height, weight, shape Psychological traits: personality, shyness, personal skills, social skills Chemical: blood type, predisposition to genetic disorders, diabetes, ect.

Complete Dominance In a heterozygous genotype, Bb, the dominant allele always appears in the phenotype

Complete Dominance For example, for one of the gerbil fur color genes, that wild type agouti/brown allele (B) is completely dominant to the black (b) allele of the same gene. Bb gerbils are brown. And you can't tell by looking at a brown gerbil whether it is BB or Bb, no matter how closely or carefully you look.

Incomplete Dominance Neither allele is dominant, they are both partially expressed Blended

Sickle-Cell Anemia fatal anemia marked by sickle-shaped red blood cells, Causes pain in the joints, fever, leg ulcers, and jaundice. Incomplete Dominance RR ’

Sickle-Cell Genes Alleles R = round red blood cell R’ = sickle red blood cell Geneotypes RR = all round blood cells R’R’ = all sickle blood cells RR’ = half round and half sickle blood cells

Codominance Both alleles of a gene pair in a heterozygote are fully expressed, Neither one being dominant or recessive to the other.

Codominance Human Blood Types

Inheritance Patterns AB is codominant A and B are equal AO and BO is complete dominance O is recessive

X-linked Traits Genes found on the X chromosome, but not the Y Girls: X r X r or XX r Boys :X r Y Carrier: mother can carry the allele, but not get the disorder Carrier: X X r

X-Linked Disorders 1.Color blindness 2.Hemophilia 3.Duchene Muscular Dystrophy

Color Blindness Red and green look like gray C = ability to see colors c = color blind to red and green Males are more likely to be colorblind They only need one recessive gene X c Y males or X c X c females

W hat numbers do you see ?