A human cell holds about 2.0 m of DNA in a nucleus about 6.0 µm wide, shared among 46 chromosomes…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A human cell holds about m of DNA in a nucleus about µm wide, shared among chromosomes. How long is the DNA in micrometres? How many times the width of the nucleus is that? On average, how much DNA is in one chromosome, in centimetres?
Need a reminder? The key ideaShow
The nuclear envelope has two membranes and pores. Nucleoli have no membrane and make rRNA. Chromatin is DNA, histones, non-histone proteins and RNA. The centromere sits in the middle (metacentric), a little off the middle (sub-metacentric), near one end (acrocentric) or at the end (telocentric).
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. In micrometres. µm.
Step 2. Against the nucleus. times its width.
Step 3. Per chromosome. cm.
Answer: µm, about times the width of the nucleus, and about cm in each chromosome. The chromatin must be packed very tightly.
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