1. Variations in Mendel's Theories
Quiz 7D
Variations in Mendel's Theories

2. Variations in Mendel's Theories
Incomplete dominance
Codominance
Multiple gene inheritance
Sex-Linked traits

3. Incomplete dominance
a type of inheritance in which the genes expressing a particular characteristic are neither dominant or recessive; two traits combine or blend together to produce a different trait (a blend of two traits) (when offspring of two homozygous parents show an intermediate phenotype)

4. Incomplete dominance
example: flower color in snapdragons & four o’clock flowers

5. Codominance
In codominance the dominant and the recessive traits are both expressed.
Example:
roan cattle

6. Codominance
In incomplete dominance neither allele is fully dominant. This is different from codominance, in which both alleles are fully expressed, resulting in organisms that display the characteristics of both parents.

7. Codominance
In codominance, both alleles are expressed independently and are uniquely recognizable.

8. multiple gene inheritance
multiple gene inheritance (also called Polygenic Inheritance)- two or more genes producing a single trait (examples: hair color, skin color, eye color, height, intelligence, body build, etc.)

9. How to work incomplete dominance problems.
purebred red X purebred white carnations

10. How to work incomplete dominance problems.
Step 1: possible pheotypes and genotypes
Pheno
Geno
use two different letters to represent genes
use lower case letters
red
white
pink rr ww rw
purebred red X purebred white carnations

11. How to work incomplete dominance problems.
Step 2: parent genotypes w w
purebred red X purebred white carnations

12. How to work incomplete dominance problems.
Step 3:
fill in possible
genotypes of
offspring w w r w r w w r w r
purebred red X purebred white carnations

13. How to work incomplete dominance problems.
Step 4:
Genotipic ratio
Phenotipic ratio w w r w r w w r w r
red:white:pink
rr:ww:rw
0:0:4
purebred red X purebred white carnations