11 Questions
Which genotype corresponds to Type AB blood?
AB
Which allele represents Type O blood in the I gene notation?
i
What type of inheritance do the A and B alleles follow?
Codominant
Which genotype does NOT result in Type A blood?
AB
When a genotype is 'homozygous', what is the composition of the alleles?
Dominant + Dominant
In incomplete dominance, how are the alleles represented?
Two capital letters, one with an apostrophe
What is an example of a genotype displaying codominance?
BW
Which statement best describes incomplete dominance?
Neither allele is fully dominant, and the phenotype is a mix of both.
Which of the following is NOT an example of codominance?
A red flower and a white flower cross to produce pink flowers.
Which of the following best explains codominance?
Both alleles are dominant and both traits are expressed equally in the phenotype.
Which example illustrates incomplete dominance?
A pink flower resulting from a cross between a red flower and a white flower.
Study Notes
ABO Blood Types
- Genotype-Phenotype Correlation: AA and AO genotypes correspond to Type A blood, BB and BO genotypes correspond to Type B blood, AB genotype corresponds to Type AB blood, and OO genotype corresponds to Type O blood.
Blood Type Gene and Alleles
- The blood type gene is represented by I and has three alleles: IA for A, IB for B, and i for O.
Homozygous vs Heterozygous
- Homozygous: A genotype with two identical alleles, e.g., AA or BB.
- Heterozygous: A genotype with two different alleles, e.g., AO or BO.
Inheritance Pattern
- ABO blood types follow both Codominant and Simple Dominant inheritance patterns.
- A and B alleles are codominant with each other.
- A and B alleles are both dominant over the O allele.
Exceptions to Mendel's Laws
- Incomplete Dominance: When neither allele is fully dominant over the other, resulting in a blended phenotype.
- Codominance: When both alleles are equally expressed in the phenotype.
- Multiple Alleles: When a gene has more than two alleles, e.g., three or more options for two alleles.
Incomplete Dominance
- Representation: Incomplete dominance is represented by two capital letters, one with an apostrophe (e.g., R and R').
- Phenotype: The combination of two alleles results in a mixed phenotype.
Codominance
- Definition: Codominance occurs when both alleles of a gene are dominant and equally expressed in the phenotype.
- Representation: Codominance is represented by two capital letters (e.g., B for Brown and W for White).
- Phenotype: The heterozygous phenotype exhibits both traits equally.
Examples of Codominance in Animals
- Speckled: The combination of B (Black) and W (White) alleles results in a speckled phenotype.
- Genotype-Phenotype Correlation: ww corresponds to White, BB corresponds to Black, and BW corresponds to Speckled.
Learn about the different genotypes and phenotypes of ABO blood types, including the alleles that determine them. Understand the concept of homozygous and heterozygous blood types.
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