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