Mendelian Genetics

Heterozygous dominant individuals carry both the dominant and recessive alleles, expressing the dominant trait while still carrying the recessive allele.

Brown eyes are a dominant trait, meaning that the presence of even one dominant allele for brown eyes will result in the expression of brown eyes.

In a monohybrid cross, where one gene with two alleles is being considered, the expected ratio of dominant to recessive offspring is 3:1.

Cystic Fibrosis, Huntington's Disease, and Sickle Cell Anemia are all examples of recessive traits in humans, meaning that both copies of the gene must carry the recessive allele for the trait to be expressed.

Alleles are different forms of a gene that occupy the same locus on homologous chromosomes.

In a dihybrid cross, where two genes with two alleles each are being considered, the expected phenotypic ratio is 9:3:3:1.

Genotype refers to the genetic makeup of an individual, specifically the combination of alleles they carry for a particular gene.

ABO Blood Groups are an example of codominance, where both alleles are expressed in the phenotype, resulting in multiple distinct phenotypes.

Phenotype refers to the observable characteristics of an individual, such as physical appearance, behavior, and biochemical properties.

In a testcross, one parent is homozygous recessive, while the other parent is heterozygous dominant or unknown.

The law of independent assortment states that alleles of different genes assort independently of each other during gamete formation, meaning that the inheritance of one gene does not influence the inheritance of another gene.

Eye Color, Height, and Skin Color are all examples of polygenic traits, which are influenced by the interaction of multiple genes.

The law of dominance states that the dominant allele is always expressed in the phenotype, while the recessive allele is only expressed in the phenotype when homozygous.

Hemophilia is an example of a sex-linked trait, as the gene responsible for the disorder is located on the X chromosome.

Genetic variation is important because it allows for adaptation to changing environments, as individuals with favorable traits are more likely to survive and reproduce.