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Phenotypes and Genotypes

Science, Grade 6

Phenotypes and Genotypes

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Table Of Contents: Phenotypes and Genotypes

1. What Are Genotypes and Phenotypes?

A genotype refers to the genetic makeup, or allele combinations, of an organism. A phenotype is the physical appearance of an organism.

2. Dominant and Recessive Phenotypes

If a dominant allele is present, then the phenotype will always be the dominant trait. A phenotype will be the recessive trait when two copies of the recessive allele are present.

3. BB x bb Cross

In this Punnett square, the parental cross results in offspring with only one allele combination. All the offspring would have the same genotype and phenotype.

4. BB x Bb Cross

The offspring in this Punnett square have two different genotypes, but all have the same phenotype.

5. Bb x Bb Cross

For this cross there are three possible genotypes and two possible phenotypes.

6. Probability for a Bb x Bb Cross

You could predict that 75% of the offspring would have black fur and 25% white fur. This is the same percentage that Mendel observed when crossing the F1 generations of pea plants.

Phenotypes and Genotypes

Science, Grade 6