1. Modes of Inheritance
Biology
Mrs. Harper
1/25/18

2. January 25, 2018

3. Do Now 11/17/15

4. Modes of Inheritance: unique ways to inherit traits
FOUR MODES OF INHERITANCE
1. Incomplete Dominance
2. Codominance
3. Multiple Alleles
4. Polygenic Traits

5. Incomplete Dominance
1. Incomplete dominance is where one allele is not completely dominant over the other allele.
2. If red flowers (RR) were crossed with white flowers (rr) you would think that they would only make red flowers (Rr).
The genotypes will be Rr but the flowers will be pink because– the dominance is not complete.
4. ***Heterozygous individuals produce a new phenotype.

6. Incomplete Dominance
Red- RR
White – rr
Pink- Rr

7. Codominance
4. In codominance, both alleles express themselves independently in the phenotype.
5. Both alleles contribute to the phenotype of the organism – one isn’t dominant or recessive, they are both expressed.
6. Not all organisms are just one color. Lots of things are spotted, speckled or multiple colors and these use codominant traits.

8. Codominance

9. Multiple Alleles
7. This is a type of inheritance that has more than two possible alleles for a trait.
8. Most of the traits that we have looked at have had two alleles: like B or b, T or t.
9. But some traits have more than two alleles – they have multiple alleles. They could have: A, B, or O (for blood type).

10. Multiple Alleles

11. Polygenic Traits
10. Polygenic traits are controlled by two or more genes.
11. Polygenic traits often show a wide variety of phenotypes – it isn’t either just black or brown, it could be many colors.
12. Polygenic traits are responsible for the wide range of different skin colors in humans. There are more than 4 different genes that determine this trait.

12. Which mode of inheritance is this speckled dog?

13. Which mode of inheritance is variety in skin color?

14. Which mode of inheritance a new phenotype for heterozygous?

15. Which mode of inheritance for the diversity in blood types?

16. Practice
Red (R) flowers are dominant to white (r) flowers, but when heterozygous, they produce pink flowers, meaning they are INCOMPLETELY DOMINANT.
If a white flower crosses with a pink flower, what percentage of the offspring will be pink?

17. Practice Genotypes for Type A __________________
Human blood types are determined by genes that follow the CODOMINANCE pattern of inheritance. There are two dominant alleles (A and B) and one recessive allele (O).
Genotypes for Type A __________________
Genotypes for Type B________________
Genotypes for Type AB__________________
Genotypes for Type O _____________
AO or AA
BO or BB AB OO
If my mother is Type A, my father is Type B, can I have Type O?

18. Practice

19. Assignment
Work on the Modes of Inheritance Worksheet independently on CODE RED.
Unfinished classwork is homework
I will pass back your quizzes shortly.