Non-Mendelian Genetics

1
Non-Mendelian Genetics

• is about other patterns of inheritance

2
Exceptions to the Rule

• Incomplete Dominance
• Codominance
• Multiple Alleles
• Polygenic Traits
• Sex-Linked Traits

3
Incomplete Dominance

• Neither allele is completely dominant over the
  other
• Heterozygotes looks somewhere in between

4
Codominancetwo dominant alleles are expressed
at the same time
CRCR
CWCW
CRCW
5
Codominance

• Sickle-Cell Anemia is another codominant trait.

NA
NA
NSNA
NSNA
NS
NANormal RBC
NANA
NANA
NA
NSSickle Cell RBC
6
Multiple Allelestraits with more than 2 alleles

• Blood type has 3 alleles A, B, O
• A and B are codominant over O
• O is recessive

Phenotype Genotype Can Receive From Can Donate To
A IAIA, IAi A, O A, AB
B IBIB, IBi B, O B, AB
AB IAIB A, B, AB,O AB
O ii O A, B, AB, O
7
Multiple Allelestraits with more than 2 alleles
8
Polygenic Traits

• Traits controlled by 2 or more genes
• Examples in Karyotype lab

9
What are Sex-Linked Traits?

• Traits that are located on one of the sex
  chromosomes (XY)

Hemophilia Failure of blood to clot
Alix and Nicholas II
Muscular Dystrophy wasting away of muscles
10
Can I inherit a sex-linked disease?
Mothers (XX) can pass disorders to both sons (XY)
and daughters (XX)
Fathers (XY) can only pass disorders to daughters
(XX)
Most disorders are carried on the X chromosome,
so males are more likely to inherit them.
11
(No Transcript)
12
Pedigree for Colorblindness
13
Summary

• Can ALL traits be explained by the Mendelian
  model of inheritance?
• Why or why not?