Final answer:
Dominant genes are expressed in an individual's phenotype, while recessive genes are only expressed when an individual has two copies of the recessive allele. Sickle cell anemia and albinism can be explained in terms of Mendelian genetics. Punnett squares are used to analyze the inheritance of dominant and recessive genes.
Step-by-step explanation:
Dominant and Recessive Genes
Dominant genes are those that are expressed in an individual's phenotype, or physical characteristics, when present. They mask the expression of recessive genes. Recessive genes are only expressed when an individual has two copies of the recessive allele.
For example, sickle cell anemia is caused by a recessive gene. Individuals with the disease have two copies of the recessive allele, while individuals who are carriers have one copy of the recessive allele and one copy of the dominant allele. Albinism, on the other hand, is caused by a recessive gene that affects the production of melanin, resulting in a lack of skin, hair, and eye pigmentation.
Punnett Squares
Punnett squares are used to predict the possible genotypes and phenotypes of offspring in a genetic cross. For example, when crossing two individuals who are both carriers for sickle cell anemia (heterozygous), the Punnett square shows that there is a 25% chance of having a child with sickle cell anemia, a 50% chance of having a child who is a carrier, and a 25% chance of having a child who is not a carrier.