Answer the following questions for autosomal conditions such as PKU.
If both parents are heterozygous carriers of a mutant allele, what is the chance that their first child will be homozygous recessive for the mutation?

In diploid organisms there are _______ chromosomal copies. In haploid organisms there is _______ chromosomal copy.

After a diploid cell undergoes meiosis, it divides to produce…

Answer the following questions for autosomal conditions such as PKU.

If the first child of parents who are both heterozygous carriers of a recessive mutant allele is homozygous recessive, what is the chance the second child of the couple will be homozygous recessive? What is the chance the second child will be a heterozygous carrier of the recessive mutation?

Answer the following questions for autosomal conditions such as PKU.

Parents who are each heterozygous carriers for a recessive mutant allele have a child who does not have the condition. What is the chance this child is a heterozygous carrier of the condition?

Homocystinuria is a rare autosomal recessive condition on the RUSP list of conditions screened by newborn genetic testing. The condition results from a mutation that blocks the degradation of the amino acid methionine. The absence of a critical enzyme causes the buildup of the compound homocysteine, which is one of the intermediate compounds in the methionine breakdown pathway. Homocystinuria causes mental impairment, heart problems, seizures, eye abnormalities, and a number of other symptoms that shorten life if not treated. The condition is treated by a specialized diet that is low in methionine and by the ingestion of several supplements.

The low-methionine diet must be maintained throughout life to manage homocystinuria. Why do you think this is the case?

Homocystinuria is a rare autosomal recessive condition on the RUSP list of conditions screened by newborn genetic testing. The condition results from a mutation that blocks the degradation of the amino acid methionine. The absence of a critical enzyme causes the buildup of the compound homocysteine, which is one of the intermediate compounds in the methionine breakdown pathway. Homocystinuria causes mental impairment, heart problems, seizures, eye abnormalities, and a number of other symptoms that shorten life if not treated. The condition is treated by a specialized diet that is low in methionine and by the ingestion of several supplements.

Why do you think eating a low-methionine diet is critical to controlling homocystinuria?

The diploid number of the hypothetical animal Geneticus introductus is 2n = 36. Each diploid nucleus contains 3 ng of DNA in G₁.

Complete the following table by entering the number of chromosomes and amount of DNA present per cell at the end of each stage listed.

In diploid yeast strains, sporulation and subsequent meiosis can produce haploid ascospores, which may fuse to reestablish diploid cells. When ascospores from a segregational petite strain fuse with those of a normal wild-type strain, the diploid zygotes are all normal. Following meiosis, ascospores are petite and normal. Is the segregational petite phenotype inherited as a dominant or a recessive trait?