Genetics: Inheritance Patterns & Pedigrees

• A genetic diagram illustrates X-linked inheritance through a cross between a hemophilic man and a healthy woman.

Genetic Cross Example: ABO Alleles

• A genetic diagram demonstrates a cross between a homozygous female with type A blood and a heterozygous male with type B blood.
• The female has a 100% probability of passing the IA allele, as she has the IAIA genotype.
• The male has a 50% chance of passing either the IB or I0 allele because his genotype is IBI0
• The probability of offspring genotypes is 0.5 for IAIB and 0.5 for IAIO.
• The phenotypic ratio of offspring is 1:1 for type AB blood versus type A blood.

Pedigree Charts

• A pedigree chart shows the ancestral history of related individuals, displaying inheritance across generations.
• Generations are arranged from oldest to youngest, top to bottom.
• Circles typically represent females, and squares represent males.
• Shaded shapes indicate individuals expressing a trait.
• Horizontal lines connect parents, while vertical lines lead to their children.
• Generations are labeled with Roman numerals, individuals with Arabic numerals.
• A horizontal line between a square and a circle represents a cross, or a union.
• A vertical line from a cross leads to a single child or to a horizontal line if there are more children.
• The provided fur color pedigree indicates that grey shapes represent individuals with black fur, and a white circle signifies an individual with white fur.

Population Variations

• Variations are differences among individuals of the same species.
• Phenotypic variations are differences in observable characteristics.
• Genetic variations are differences in genotypes.
• Phenotypic variation includes continuous and discontinuous types.
• Continuous variation involves a range of variations between two extremes without distinct categories, creating a continuous range of phenotypes (e.g., height and weight).
• A normal distribution curve results from plotting continuous variation data, such as height in a population.
• The greatest number of individuals falls within the middle range of heights, with fewer at extreme ends.

Explore X-linked inheritance, ABO allele crosses, and pedigree charts. Understand genetic diagrams illustrating hemophilia and blood type inheritance. Learn to interpret pedigree symbols and track traits across generations.