rr ww rw with incomplete dominance, neither allele is completely dominant nor completely recessive....

ARE THERE EXCEPTIONS TO MENDEL’S IDEAS OF

DOMINANT AND RECESSIVE?

YES!!

WHAT DO YOU THINK WOULD HAPPEN? HOW

ABOUT MENDEL?

ACCORDING TO MENDEL, WE SHOULD

SEE 100% RED HETEROZYGOUS

OFFSPRING..

WE SEE THIS INSTEAD.

RR WW

RW

COMPLEX PATTERNS OF

INHERITANCECHAPTER 7

(GET EXCITED!!)

INCOMPLETE DOMINANCE

• With incomplete dominance, neither allele is completely dominant nor completely recessive.

--> Heterozygous phenotype is an ______________ between the two homozygous phenotypes

=+

intermediate

INCOMPLETE DOMINANCE

CODOMINANCE

• With codominance, both alleles are dominant and equally expressed.

--> both alleles express themselves in a heterozygous organism

• for example, and sickle cell anemiaroan cows

+ =

fully

CODOMINANCE

+

Sickle cell

Normal red blood cell

SICKLE CELL ANEMIA

• Changes in hemoglobin cause red blood cells to change to a sickle shape.

• People who are heterozygous for the trait have both normal and sickle-shaped cells.

• Sickle red blood cells clump together and stick to the walls of blood vessels, blocking blood flow.

• This can cause severe pain and permanent damage:brain, heart, lungs, kidneys, liver, bones, and spleen.

SYMPTOMS

POLYGENIC TRAITS

• Traits that are influenced by ____________________

• for example, skin color, height, eye color, and fingerprint pattern

multiple gene pairs

http://www.youtube.com/watch?v=pmZV36XgXaI

MULTIPLE ALLELES

• form of inheritance that is determined by _________ __________• for example, human blood types

-Type A

-Type B

-Type AB

-Type O

more than 2 alleles

BLOOD TYPES

• Antigens are ___________ foreign to the _____.• Rh factors can either be ___________ or _____________

+-

substances

body