Understanding Codominance in Genetics

The video tutorial explores codominance, a genetic concept where both alleles in a heterozygote are fully expressed, resulting in a third phenotype. It contrasts codominance with dominant and recessive inheritance using examples of flower petal color and cow coat color. The tutorial explains how to represent codominant alleles using genetic notation and demonstrates the use of a Punnett square to calculate genotype and phenotype ratios, highlighting the unique inheritance patterns of codominance.

What is the main difference between codominance and simple dominance in genetics?

• Codominance results in a blend of traits.

• Codominance results in both traits being fully expressed.

• Codominance results in only the dominant trait being expressed.

• Codominance results in neither trait being expressed.

In the flower example, what are the possible genotypes for a red flower if red is dominant?

• Little r Little r

• Big R Big R or Big R Little r

• Big R Big R only

• Big R Little r or Little r Little r

What is the third phenotype called in the cow coat color example of codominance?

• Striped

• Roan

• Brown

• Spotted

How are alleles represented in codominance when using superscripts?

• Using numbers

• Using lowercase letters only

• Using symbols

• Using a base letter with superscripts for different alleles

What does it mean if an individual is heterozygous in a codominant trait?

• The phenotype is not expressed.

• The phenotype is the same as one of the homozygous phenotypes.

• The phenotype is a blend of both alleles.

• The phenotype is different from both homozygous phenotypes.

In codominance, how can you identify a heterozygous individual based on phenotype?

• By observing a blend of traits

• By observing a unique phenotype not seen in homozygous individuals

• By observing the dominant trait only

• By observing no traits

What is the genotype ratio for offspring in a codominant cross between two heterozygotes?

• 3:1

• 1:1

• 2:1

• 1:2:1

In a Punnett square for codominance, what does a 1:2:1 phenotype ratio indicate?

• No phenotypes are expressed

• Two phenotypes are equally expressed

• Three distinct phenotypes are present

• One phenotype is dominant

How does the interpretation of genotypes differ in codominance compared to simple dominance?

• Genotypes are interpreted the same way

• Genotypes are interpreted based on a blend of traits

• Genotypes are not interpreted

• Genotypes are interpreted to show both traits equally

What is the phenotype of an individual with a CR CW genotype in the cow example?

• Roan

• White

• Brown

• Red