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?

In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.

Describe how the codon for phenylalanine was identified.

Some proteins are composed of two or more polypeptides. Suppose the DNA template strand sequence 3′-TACGTAGGCTAACGGAGTAAGCTAACT-5′ produces a polypeptide that joins in pairs to form a functional protein.

What term is used to identify a functional protein like this one formed when two identical polypeptides join together?

In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.

What result was obtained for synthetic mRNAs containing AG repeats, that is, AGAGAGAG...?

Some proteins are composed of two or more polypeptides. Suppose the DNA template strand sequence 3′-TACGTAGGCTAACGGAGTAAGCTAACT-5′ produces a polypeptide that joins in pairs to form a functional protein. What is the amino acid sequence of the polypeptide produced from this sequence?

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?

In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.

What was the result of studies of synthetic mRNAs composed exclusively of cytosine?