Download BSC 219

BSC 219
Homework 2
5 points total
Due 9/11/12
1) De Describe the observed phenotypic ratios of an allele that is lethal to
developing homozygotes.
2) If it is a dominant allele then homozygous dominant individuals will die
during development. This means that only heterozygotes will live to
express dominant phenotype and homozygous recessives will express
recessive phenotype. With the death of homozygous dominant
individuals the phenotypic ration of survivors would be approximately
2:1 dominant to recessive. If the lethal allele is recessive, then only
those with the dominant phenotype would survive.
3) Explain a common scenario in which one gene will act in an epistatic fashion
on one or more other genes. In complex biochemical pathways it is
common for the product of one enzymatic reaction to be utilized by
later enzymes. If the gene encoding the earlier enzyme produces a
nonfunctional enzyme then the required product is not there to serve
as a substrate in later steps, thus the earlier gene would mask the
function of the later one in an epistatic relationship.
4) A man who is blood type AB and a woman who are blood type B have four
children. Is it possible for each of the four children to have a different blood
type (A,B, AB, O)? If so, how? No, there is no possible way for them to
have a child with blood type O. They could have children with type B,
AB, and even A blood if mom is genotype BO, but could not have a type O
child.
4)
Using the pedigree below, what pattern of inheritance best explains this
trait? Autosomal dominant best explains the pedigree, however, it is not
impossible to eliminate the possibility of X-linked recessive with some female
carriers.
5.
Using the pedigree below, what pattern of inheritance best explains this
trait? X-linked recessive