Pedigree Charts and Genetic Crosses

• A genetic diagram describes X-linked inheritance in a cross between a hemophilic man (XʰY) and a healthy woman (XᴴXᴴ).
• The hemophilic man produces gametes that are half Xʰ and half Y.
• The healthy woman produces all Xᴴ gametes.
• Offspring genotypes are XᴴXʰ (healthy female carrier) and XᴴY (healthy male).
• The ABO alleles include Iᴼ, Iᴬ, and Iᴮ.
• A genetic diagram depicts a cross between a homozygous female with type A blood (IᴬIᴬ) and a heterozygous male with type B blood (IᴮIᴼ).
• The female with type A blood will pass the Iᴬ allele to her offspring with a probability of 1.
• The heterozygous male will pass the Iᴮ allele to his offspring with a probability of 0.5, and the Iᴼ allele with a probability of 0.5.
• The offspring genotypes are IᴬIᴮ (blood group AB) and IᴬIᴼ (blood group AO).
• The phenotypic ratio of offspring with type AB blood to offspring with type A blood is 1:1.

Pedigree Charts

• A pedigree is a chart presenting the inheritance of a characteristic through multiple generations within a family.
• Generations are arranged from top to bottom, with the oldest at the top and the youngest at the bottom.
• Circles represent females, and squares represent males.
• Shaded shapes indicate individuals expressing the trait.
• A horizontal line between a square and circle symbolizes a cross or union.
• A vertical line from this horizontal line indicates offspring.
• Generations are numbered with Roman numerals, and individuals within each generation are numbered with Arabic numerals from left to right
• In a pedigree illustrating fur color inheritance, grey shapes represent individuals with black fur, and white circles indicate those with white fur.

Population Variations: Continuous versus Discontinuous Variation

• Variations are differences between individuals of the same species.
• Phenotypic variations are differences in observable characteristics, while genetic variations are differences in genotypes.
• Phenotypic variations are observable differences in features among individuals within the same species.
• Continuous variation involves observable variations distributed along a continuous range between two extremes, lacking distinct categories.
• Traits like height and weight exhibit continuous variation, with no fixed values but a range of possible values.
• When plotted on a graph, continuous variation data typically forms a normal distribution curve.
• A normal distribution curve shows that most individuals have heights in the middle range, with fewer individuals at extreme heights.
• Weight and other traits demonstrating continuous variation also display a normal distribution curve when graphed.

Explanation of X-linked inheritance with hemophilia and ABO blood groups. Includes the probability of offspring genotypes and phenotypes from different crosses. Focuses on the use of genetic diagrams and pedigree charts.