1. Genetics
Intermediate Traits

2. Traits Most traits are controlled by more than 1 gene
Most traits have multiple alleles

3. Incomplete dominance For some traits, neither allele is dominant
Blending occurs
Ex. Snapdragons
Cross a red flower with a white flower and get pink flowered offspring

4. Problem
A true breeding red snapdragon is crossbred with a true breeding white snapdragon. Red and white colors are considered to be incompletely dominant. What will the phenotypic ratio of their offspring be?

5. Codominance Both alleles are expressed in the same organism
Ex. Chicken feathers
Black feathered rooster + a white feathered hen = offspring with some white feathers and some black feathers

6. Problem
In a certain type of rabbit, black fur is codominant with brown fur resulting in an agouti color. If a true breeding black fur rabbit and an agouti rabbit are bred, what will the phenotypic ratio of the offspring be?

7. Multple Alleles Each organism has only 2 possible alleles for a trait
Multiple alleles for the trait may exist in the entire population
Ex. Human Blood types
A, B, AB, O

8. Blood Types A and B are CODOMINANT A and B are DOMINANT over O
Written as IA, IB, and I
IA IA produce A blood type
IA i produce A blood type
IB IB produce B blood type
IB i produce B blood type
ii proudces O blood type
What type of parents can produce offspring with any blood type?

9. Problem
A man with type O blood marries a woman with type A blood. They have a son with type O blood. Several years later they get a divorce and the wife is suing the husband for child support. Is it possible that he should have to pay?

10. Problem
A man with type O blood marries a woman with type A blood. They have a son with type B blood. Several years later they get a divorce and the wife is suing the husband for child support. Is it possible that he should have to pay?

11. Polygenetic Traits Some traits are controlled by more than one gene
Ex. In humans
Height
Eye color
Skin color

12. Intermediate Patterns of Inheritance
Pattern of Inheritance
Description
Example
Incomplete Dominance
One allele is not completely dominant over another
Snapdragons: Red flowered plant and white flowered plant crossed make pink flowered plants
Codominance
Both alleles contribute to the phenotype
Chicken variety: black feathered chicken X with a white feathered chicken = white and black feathered chicken
Multiple alleles
A gene has more than 2 alleles possible
Human blood type: IA and IB (codominant) and i
Polygenetic Traits
Traits are controlled by more than 1 gene
Human skin color: wide range of colors due to several different genes

13. Chromosomes
2 types
Autosomes are any type of chromosome other than a sex chromosome
Sex chromosomes are X and Y
Females XX – always donate an X
Males XY – determines gender of offspring

14. Sex – Linked Traits
Determined by alleles located on the sex chromosomes (X and Y chromosomes)
Males have 1 X chromosome meaning they are more likely to show a sex linked recessive trait
Ex. Albinism, hemophilia, blindness, muscular dystrophy are sex linked

15. Karyotypes Visual display of all the chromosomes in an organism
Indicate chromosomal abnormalities
Broken, missing, or extra
Down’s syndrome

16. Down’s syndrome
Results from an extra 21st chromosome

17. Turner’s syndrome Only 1 X chromosome and no Y Always Female
Usually develop normally but may result in shorter stature

18. Triple X Goes undiagnosed most of the time
Estimated 1 out of 10 girls are XXX

19. XYY syndrome
Extra Y chromosome
Only in Males

20. Klinefelter syndrome Males
Tendency to develop female-like characteristics