Science Buddies: "Ask an Expert"

Good afternoon! I am doing a science fair project that is due on January 10th, on from genes to genetic diseases; what mutations matter. Right now I am very confused on how to find and identify the amino acid sequence change and the effect in table 1. The website says to use the figure 2, but, I am not quite sure how to read or comprehend it. Thank you!!!

Welcome to Science Buddies!

If I understand your question properly you are having trouble reading the codon to amino acid figure (figure 2).
First of all, DNA is made up of 4 nucleotides, Adenine(A), Cytosine(C), Guanine(G), and Thymine(T), and when it is transcribed to RNA, the Thymine gets replaced with a Uracil, so the nucleotides for RNA are ACGU.

If you combine take the 4 nucleotides are create 3 letter combinations that makes 64 possible combinations...but we only have 20 amino acids and the stop codon to code for. This means that multiple codons will translate to one amino acid. It would be good for you to look up the three letter abbreviations for all of the amino acids.
I hope this makes sense so far, please ask questions back if you need me to make this clearer.

As for how to read the table, From the top to the bottom on the left side it lists, UCAG, those are the first position of the codon. Then on the top part of the table from left to right it lists, UCAG, those are the second positions, and the right side shows all of the possible nucleotides that could be in the third position.

I'll walk through one of the boxes to try and explain further. The top left box says that UUU and UUC code for Phe. Phe is the 3 letter abbreviation for Phenylalanine, an amino acid.

There are some amino acids that can have 6 different codons! For instance, Arginine or Arg has CGU, CGC, CGA, CGG, AGA, and AGG.

One final thought. Let's say there is a mutation in a codon, we start out with UGG and the third base gets mutated to a A, making it UGA. What would UGA code for? Also, what does UGG code for to begin with? Can you find it in the figure now?

I hope that helps!!

Thank you so much!!! I am finally starting to understand and that was a lot of help. Was the answers to your questions that UGG was Trp and that UGA was Stop Thank you so much!

I have one last question. For step f, it said to write the allele change, but, is that the protein change or the residue change. If it is the residue change, then wouldn't the amino acid sequence change be the same. It says in part 4a that the amino acid entry should match the residue change. Thank you!!!

Note from moderator: I combined your 3 questions into one thread so the expert who has been helping you will be able to easily see your additional questions. Please keep any additional questions in this same thread. Thank you.