The chromosome of the bacterium Escherichia coli has about 4.6 × 10⁶ base pairs…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The chromosome of the bacterium Escherichia coli has about base pairs. One set of human chromosomes has about base pairs. Take the distance between base pairs as and the turn as base pairs. Find the length of the bacterial DNA in millimetres, the number of turns in it, and the length of one set of human DNA in metres.
Need a reminder? The key ideaShow
In B-DNA the base pairs are apart and there are about base pairs in a turn. A codon is three bases, and a stop codon does not code for an amino acid. The mass fraction of an element in a molecule is .
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.
Step 1. Bacterial DNA. .
Step 2. Turns. turns.
Step 3. Human DNA. .
Answer: , turns and .
Check. The bacterium is about 2 micrometres long, so its DNA is almost a thousand times longer than the cell. This is possible because the DNA is tightly coiled.
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