A ribosome of a bacterium adds about 20 amino acids to a polypeptide in a second…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A ribosome of a bacterium adds about amino acids to a polypeptide in a second. An mRNA has a coding region of nucleotides, from the start of AUG to the end of the stop codon.
- How many amino acids does the polypeptide have?
- How long does one ribosome take to make it, in seconds?
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, amino acids a second.
Plan. Find the number of amino acids, then divide by the speed.
Step 1. (a) codons, which is amino acids and one stop codon.
Step 2. (b) .
Answer: ; .
Check. A protein is made in about 15 seconds, so a bacterium can make a new enzyme very quickly.
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