1. Non-Mendelian Genetics

2. Beyond
Dominant
and Recessive
Alleles

3. More Complex Patterns of Heredity
Incomplete Dominance
Codominance
Multiple Alleles
Polygenic Traits
Sex-Linked Traits

4. Incomplete Dominance – Blending of traits; heterozygous phenotype is somewhere between the two homozygous phenotypes.
Ex: Pink flower offspring of white and red flower

5. Codominance: two dominant alleles are expressed at the same time
CRCR
CWCW
CRCW

6. NSNA NSNA NANA NANA Codominance NA NA NS NA
Sickle-Cell Anemia is another codominant trait. NA NA
NSNA
NSNA NS
NA=Normal RBC
NANA
NANA NA
NS=Sickle Cell RBC

7. Codominance – Both genes expressed simultaneously; heterozygous individuals exhibit both phenotypes.
~ erminette ~

8. Multiple Alleles – Some genes have more than two alleles – not more than two alleles in an individual but more than two alleles in a population.
Full color: CC, Ccch, Cch, or Cc
Himalayan: chch or chc
Chinchilla: cchcch, cchch, or cchc
Albino: cc

9. Blood Type Four Blood Types: A, B, AB, O
Blood types refer to different carbohydrates on the surface of red blood cells
Type A Type B Type AB Type O

10. Blood Types Blood type is inherited
One blood gene is from your mom, one is from your dad
Three different alleles:
IA -- Type A carbohydrate molecules
IB -- Type B carbohydrate molecules
i -- neither type of carbohydrate molecule.

11. Blood Type
Blood types are an example of multiple alleles AND codominance
A and B are codominant over O
O is recessive

12. Phenotypes and genotypes
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 O ii
A, B, AB, O
Awesome Blood Typing Game

13. Polygenic Traits – Many traits are the result of many genes acting together.? ? ?

14. Chromosomes
Chromosomes Pairing   Body cells contain 46 chromosomes These 46 cells are arranged in 23 pairs Each of these pairs is called a homologous pair  
with one exception, each pair contains chromosomes that are exactly alike in size

16. Sex Chromosomes
Only one pair differs (23rd pair): in females this pair is alike XX in males this pair is different XY

17. We can use a Punnett square to predict the chances of having a baby boy vs a baby girl
50% chance boy; 50% chance girl
X X X Y XX XX XY XY

18. What are Sex-Linked Traits?
Traits that are located on one of the sex chromosomes (X or Y)
Hemophilia: Failure of blood to clot
Alix and Nicholas II
Muscular Dystrophy: wasting away of muscles

19. Sex-linked traits usually refer to X-linked traits
The human X chromosome is much larger than Y
So, there are more X-linked traits than Y

20. Can I inherit a sex-linked disease?
Fathers (XY) can only pass disorders to daughters (XX)
Mothers (XX) can pass disorders to both sons (XY) and daughters (XX)
In humans, the term sex-linked traits usually refers to X-linked traits.
The human X-chromosome is much larger than the Y. Thus, there are more X-linked than Y-linked traits.
Most X-linked genes have no homologous loci on the Y chromosome.
Most genes on the Y chromosome not only have no X counterparts, but they encode traits found only in males (e.g. testis- determining factor).
Examples of sex-linked traits in humans are color blindness and hemophilia. Fathers pass X-linked alleles to only and all of their daughters.
Males receive their X chromosome only from their mothers.
Fathers cannot, therefore, pass sex-linked traits to their sons.
Mothers can pass sex-linked alleles to both sons and daughters.
Females receive two X-chromosomes, one from each parent.
Mothers pass on one X-chromosome (either the maternal or paternal homologue) to every daughter and son.
Most disorders are carried on the X chromosome, so males are more likely to inherit them.