Answer: The CDC is responsible for tracking and identifying diseases to prevent the spread of the diseases. They also have a role to bring awareness of these infectious diseases. They chart the numbers of people who have contracted the disease and the numbers of people who have died from them, etc.
Answer: Not always. It depends if the individual is a hybrid- meaning they have both the dominant and the recessive gene. They can pass on the recessive gene instead of the dominant one, and assuming the other parents also passes on the recessive gene, the child will not inherit the disease.
Answer: It could happen in two main mechanisms:1) the allele responsible for the disease is recessive and so each of the parents are healthy portators of the allele (heterozygous), and all the sons which are homozygous for the allele (i.e. have two copies of the allele), with a frequency of 1:4, will be affected by disease, but not the others (heterozygouses and homozygouses for the good allele or wild type).2) the mutation responsible for the disease (that acts in a dominant manner) is not present in any of the parents but happens only during the formations of gametes, and so will be transmitted to the son.There are also other mechanisms that are less frequent and more difficult to explain in a few words.