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How do Pedigree charts work?
Can someone please explain pedigree charts to me? All I know is that squares represent males and circles represent females. I also know that when one of the shapes is colored, it means that that person is affected by something. So, what does it mean when the shape is colored half-way? I also heard that it is organized by age as well.. from youngest to oldest (left to right)/. So can you please answer these questions for me and aslo add some more information that would be helpful.
Thank you.
2 Answers
- ATP-ManLv 71 decade agoFavorite Answer
In a pedigree chart, generations are represented by Roman numerals. Each person in each generation is numbered.
Males are represented by a square and females by a circle.
A horizontal line connecting a male and female is called a marriage line.
Vertical lines represent children.
Children on the vertical line are always placed from left to right, with the child on the left being the oldest.
Determining Genotypes:
If we look at a specific trait ( earlobe shape ) there are two general shapes of earlobes. The first being individuals with the dominant, free ear lobes (E) and the recessive, attached ear lobes (e). Individuals on a pedigree chart that have unshaded symbols have at least one dominant gene, and show the dominant trait.
Rules one must follow to predict genotype:
Any person on a pedigree chart that has a shaded symbol must be assigned two (2) recessive genes.
Place lower case letters under the person's symbol.
Any person on a pedigree chart that has an unshaded symbol must be assigned a dominant gene.
Place a capital letter under the person's symbol.
To determine the second gene for persons who show a dominant trait a Punnett square must be used.
