Polygenic Inheritance
Incomplete Dominance
Codominance
Environmental Factors
Heredity
 Genetics
 Study of GENES
 Heredity
 Study of
INHERITANCE PATTERNS
 Passing of traits from
parents to offspring
Types of Complex Inheritance
 Polygenic
 Polygon: Multiple sides
 Polygamy: Multiple marriages
 Polytheism: Multiple gods
 Polygenic: Multiple GENES
 Incomplete Dominance
 Codominance
 Environmental Factors
Polygenic Inheritance
 Multiple alleles (more than two options)
 Genes spread over different locations or chromosomes
 MANY different combinations and mixes
 Examples:
 Hair color
 Eye color
 Skin color
 Degrees of extremes
(Dark to light, etc)
http://discovermagazine.com/2007/mar/eye
-color-explained
Incomplete Dominance
 MIXING
 Snapdragons:
 Red (R1)
 White(R2)
 Pink(R1R2)
http://www.massasoit-bio.net/courses/136/136_courseassets/cummings_animations/snapdragon_crosses.html
Hair Type
 Straight Hair: Homozygous: Incomplete Dominant
 Curly Hair: Homozygous: Incomplete Dominant
 Wavy Hair: Heterozygous: A mix (Straight and Curly)
Environmental Factors
 Some genes are only expressed under certain
ENVIRONMENTAL CONDITIONS
Hydrangea
Arctic Fox
http://www.interiorofficeplants.com/http:/www.interiorofficeplan
ts.com/why-hydrangeas-are-different-colors/
Gender Determination
 Alligators, Tortoises and Turtles
 Temperature changes the gender of offspring!
EXAMPLE:
 Female if Hot
 Male if Cold
Codominance
 Multiple alleles are DOMINANT over others
 Blood Type:
 Dominant Types: A and B
 Recessive Types: O
 AA or AO=Type A
 BB or BO=Type B
 AB=Type AB
 OO=Type O
http://www.google.com/imgres?um=1&hl=en&sa=N&rlz=1C1SNNT_enUS408US408&authuser=0&biw=1366&bih=66
7&tbm=isch&tbnid=8PsfdtfL6lbTEM:&imgrefurl=http://learn.genetics.utah.edu/content/begin/traits/blood/types.h
tml&docid=MBMmwYaFY_nyrM&imgurl=http://learn.genetics.utah.edu/content/begin/traits/blood/images/ABObl
oodsystem.gif&w=489&h=285&ei=4cdWT46aLOnE2wX08cnlCQ&zoom=1&iact=hc&vpx=735&vpy=198&dur=2272&h
ovh=171&hovw=294&tx=158&ty=70&sig=115824390853095710786&page=1&tbnh=115&tbnw=197&start=0&ndsp=18&ved
Rh+ and Rh Simple dominance and recessiveness
 Rh+ is the DOMINANT trait (R)
 Rh- is the RECESSIVE trait (r)
 + (Positive) simply means you carry Rh factor
Genotype
Phenotype
RR (++)
Positive
Rr (+-)
Positive
Rr (--)
negative
Want to know your blood type?
 Legally, we can’t do the lab anymore 
 BUT…you can find out by Donating Blood 
 Here’s an example though…
 My blood type is O (I’m a universal donor)
 My brother is AB (He’s a universal acceptor)
 What are my parents?
 (Let’s do this on the board…it’ll be easier)