The coding region of an mRNA, from the first base of AUG to the last base of the stop codon, has…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The coding region of an mRNA, from the first base of AUG to the last base of the stop codon, has nucleotides. Take the mass of an average amino acid as Da.
- How many codons does the coding region have?
- How many amino acids does the polypeptide have?
- What is the mass of the polypeptide in kilodaltons (kDa)?
Need a reminder? The key ideaShow
A tRNA has an anticodon at one end and an amino acid acceptor end at the other. The ribosome reads the mRNA from 5′ to 3′, from AUG to a stop codon. A stop codon has no amino acid, so a coding region of nucleotides makes amino acids, of about 110 Da each.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. nucleotides, Da for each amino acid.
Plan. Codons, then amino acids, then mass.
Step 1. (a) codons.
Step 2. (b) One of them is the stop codon, so there are amino acids.
Step 3. (c) .
Answer: ; ; .
Check. The 5′ and 3′ UTRs are not counted, because they are not in the coding region.
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