Expert: Florence M Rollwagen - 11/3/2008

Question
hello, i am a student in Canada. i have difficulty solving some questions...

Q1. Sickle-cell anemia is a genetic disease that occurs when the amino acid valine takes the place of glutamic acid during translation of a hemoglobin chain. which of the following causes this disease?
 a. CTT changes to CAT
 b. GAA changes to GUU
 c. CUC changes to CAG
 d. CAG changes to CTC

Q2. the following is a DNA base sequence: ACG CCT ATA CCA AGT. Explain what would occur during the translation of this gene if ATA underwent a mutation and was converted to ATT.

i hope you will help with some explanations.
thanks for your time :)

Answer
Hi Travis:  Thanks for your question.

This problem is answered by remembering the base-pairing rules.  A pairs with T, G pairs with C.  In RNA, T is replaced by U.

Q 1.  Do you have access to the Genetic Code chart?  There must be one in your textbook.  Just look up the codons for valine and glutamic acid and determine their differences.

Q 2.  Again, remember the base pairing rules.  the sequence ACG is the codon for which amino acid?  Look it up in your Genetic Code chart.  Do the same for the other four codons.  So what does ATA code for?  What does ATT code for?

Genetic Code:  http://en.wikipedia.org/wiki/Genetic_code

Hope this helps.  Please write back if you have more questions.

FM Rollwagen, PhD