Complex Patterns of Inheritance
Jacob Caldwell Isaac Oesterling
Dominance
- Definition: Where there is two alleles one dominant, one recessive. The dominant covers up the recessive.
- Example Organism and Trait: Human, eye color, brown is dominant to blue
- Ex. problem: A heterozygous brown eyed parent, mates with a homozygous blue eyed parent. What are the possible genotypes?
- A. BB, bb
- B. bb
- C. Bb, bb
- D. Bb
Multiple Alleles
- Definition: Traits controlled by more than one allele
- Offspring Phenotype: Multiple phenotypes
- Example Organism and Trait: Human, Blood type: A, B, AB, O.
- Ex. Problem: Someone with O type blood mates with someone with blood type A.What are the possible phenotypes?
- A. 25%A 75%B
- B. 100%A
- C. 50%B 50%O
- D. 50%A 50%O
Incomplete Domincance
- Definition: There is not a specific dominant allele, neither allele is expressed over its pair.
- Offspring Phenotype: In heterozygous incomplete dominant it produces a mix of the two traits rather than one masking the other.
- Example Organism and Trait: Cross pollination with snapdragon plants one being red one being white, producing a pink flower. A child's wavy hair comes from one parent having straight hair and one having curly hair.
- Ex. Problem: If a homozygous white flower mates with a pink flower what will the possible phenotypes?
- A. WW, RW
- B. RR, WW
- C. RW
- D. RW, RR
Codominance
- Definition: Both alleles are fully expressed
- Offspring Phenotype: Heterozygous offspring exhibit both alleles
- Example Organism and Trait: The sickle cell and chickens with black and white feathers.
- Ex. Problem: If a speckled Guinea pig mated with a homozygous black guinea pig what are the possible phenotypes?
- A. BB, BW
- B. BW
- C. WW
- D. BW, WW
Polygenic Traits
- Definition: Traits controlled by two or more genes not just alleles
- Offspring Phenotype: Phenotype is a range
- Example Organism and Trait: Human height and skin color
- Ex. Problem: If two very tall parents have a baby, will it most likely be tall or short?
- A. Tall
- B. Short
- C. Cucumber
- D. FireTruck
Answer Key
- C
- D
- A
- A
- A