27.2 human traits
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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: XrXr or XXr
• Boys :XrY
• Carrier: mother can carry the allele, but not get the disorder
• Carrier: X Xr
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
• XcY males or XcXc females
What numbers do you see ?