Mendelian Genetics

Created March 2020, Offline version here
Video by Paul Anderson, also on his website Bozeman Science.

    The first cross is referred to as the parental cross and their offspring is referred to as the generation. Purple is dominant to white. The PP or Pp produce a purple flower while the genotype pp produces a white flower. A simple punnett square can help determine the phenotypic and genotypic ratio of a cross. For example, PP x Pp produces a phenotypic ratio reduced to and a genotypic ratio of 2:2:0. Genotypes are made up of alleles. A parent with the following genotype ‘Pp’ has two alleles they can pass on to an offspring. The offspring has a 50% chance of getting a dominant allele (P) as well as a 50% chance of getting a recessive allele (p). According to Mendel’s , the alleles separate randomly. Linked genes are not a part of . Red hair and freckles are examples of linked genes and are found on the same chromosome. Round (R) is dominant to wrinkled (r). There are three combinations that the two alleles (R and r) can combine to form. A genotype can be homozygous (rr), homozygous (RR), or heterozygous (Rr). genotypes are known as hybrids. Round (R) is dominant to wrinkled (r) and yellow (Y) is dominant to green (y). A parent with the genotype RRYy is homozygous dominant for . Round (R) is dominant to wrinkled (r) and yellow (Y) is dominant to green (y). The probability that a parent with a genotype RrYy will have an offspring that is round is . Huntington’s disease is a dangerous disease that attacks the nerve fibers in the brain. If we look at a pedigree for this disease, we can see that it is present in every generation. Therefore, it is safe to say that Huntington’s disease is a trait. Individuals with Huntington's disease can be either homozygous dominant or heterozygous. Since the mutation results in the disease, it is safe to say that the genotype of the original version of the gene or the wild type is . Huntington's disease is a dominant disease. The chances of an affected and a wild type parent producing an affected offspring is if the mother is a hybrid and if the mother is homozygous dominant.