The law of segregation
- Gregor Mendel studied inheritance of traits in pea plants. He proposed a model where pairs of "heritable elements," or genes, specified traits.
- Genes come in different versions, or alleles. A dominant allele hides a recessive allele and determines the organism's appearance.
- When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly. This is known as the law of segregation.
- A Punnett square can be used to predict genotypes (allele combinations) and phenotypes (observable traits) of offspring from genetic crosses.
- A test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous.
Mendel's model: It started with a ratio
Mendel's model of inheritance
Mendel's model: The law of segregation
The test cross
Is that Mendel's complete model of inheritance?
Check your understanding
- Imagine that you are a rabbit breeder with two purebred rabbits, a male with black fur and a female with tan fur. When you cross your rabbits, all of the kits (baby rabbits) have tan fur.Which trait is dominant, and which is recessive?
- Which statement best describes the relationship between genotype and phenotype?