Human pedigrees describe the interrelationships between parents and children, over generations, regarding a specific trait.
Peas are convenient subjects for genetic research, whereas humans are not. Mendelian inheritance in humans is difficult to study because humans produce relatively few offspring (as compared to most other species) and they have a generation time of about 20 years.
These two factors, make it impossible to design breeding experiments using humans. Nonetheless, there are few traits that are passed on by Mendelian inheritance (e.g., dimples, freckles, and hairlines).
New techniques in molecular biology have led to many breakthrough discoveries, but basic Mendelism endures as the foundation of human genetics. Unable to manipulate the mating patterns of people, geneticists must analyze the results of matings that have already occurred. They do so by collecting information about a family's history for a particular trait and assembling this information into a family tree describing the interrelationships of parents and children across the generations the family pedigree(The record of descent of an animal, showing it to be purebred.)
Human pedigrees describe the interrelationships between parents and children, over generations, regarding a specific trait. Mendel's laws of inheritance can be used to analyze the pedigree and genotypes of the individuals in the pedigree. A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. These diagrams make it easier to visualize relationships within families, particularly large extended families. Pedigrees are often used to determine the mode of inheritance (dominant, recessive, etc.) of genetic diseases.
Pedigree analysis help us predict the future
Human pedigrees describe the interrelationships between parents and children, over generations, regarding a specific trait Probability rules: The probability scale ranges from 0 to 1. An event that is certain to occur has a probability of 1, while an event that is not certain has a probability of 0. With a coin that has heads on both sides, the probability of tossing heads is 1, and the probability of tossing tails is 0. With a normal coin, the chance of tossing heads is 1/2, and the chance of tossing tails is 1/2.
Tossing a coin illustrates an important lesson about probability. For every toss, the probability of heads is 1/2. The outcome of any particular toss is unaffected by what has happened on previous trails. We refer to phenomena such as coin tosses as independent events. Each toss of a coin, whether done sequentially with one coin or simultaneously with many, is independent of every other toss. And like two separate coin tosses, the alleles of one gene segregate into gametes independently of another gene's alleles ( the law of independent assortment). Two basic rules of probability can help us predict the outcome of the fusion of such gametes in simple monohybrid crosses and more complicated crosses.
Laws of probability govern Mendel's laws
Mendel's laws of segregation and independent assortment reflect the same rules of probability that apply to tossing coins, rolling dice, and drawing cards from a deck. These two basic rules of probability can help us predict the outcome of the fusion of such gametes in simple monohybrid crosses and more complicated crosses.
The multiplication rule states that to determine this probability, we multiply the probability of one event (one coin coming up heads) by the probability of the other event (the other coin coming up heads). By the multiplication rule, then, the probability that both coins will land heads up is 1/2 × 1/2 = 1/4.