Homozygous: An organism with two of the same alleles for a particular trait.
Heterozygous: An organism with two different alleles for a particular trait.
Fundamental Laws of Genetics
Law of Segregation: States that two alleles for each trait separate during meiosis.
Law of Independent Assortment: Indicates that genes on separate chromosomes sort independently during meiosis.
Pedigree Functions
Function of a Pedigree: A diagram that traces the inheritance pattern of a particular trait through generations.
Inheritance Patterns
Codominance: A genetic scenario where both alleles for a trait are fully expressed.
Example: Type AB blood, where both A and B alleles are expressed equally.
Incomplete Dominance: Occurs when the resulting phenotype is a blend of both parental traits.
Sickle Cell Trait and Malaria
In central Africa, high malaria rates result in the heterozygous state being protective; individuals with one sickle cell allele are resistant to malaria.
Genetic Complexity
Multiple Alleles: The presence of more than two alleles for a genetic trait.
Epistasis: The interaction of alleles, where one allele can mask the effects of another allele.
Sex-Linked Traits
These are influenced by genes located on the X chromosome, with examples including red-green color-blindness.
Polygenic Traits
Traits controlled by more than two genes have a polygenic inheritance pattern; an example is skin color, which is influenced by multiple gene pairs.