How big is DNA compared to, say, a skin cell?

Factual Questions
1

So let’s say I get really small and find myself standing in front of a recently disembodied skin cell. A live one. The cell, relative to me, is as big as a 2000 square foot split level house.

I wanna get a look at the chromosomes but have no idea what to look for. How big are they (before unbundling)? And assuming they are all unraveled and doing their magical DNA thing, how thick/long are they?

2

Here’s a relatively good interactive tool - Cell Size and Scale

It even uses a skin cell and an X chromosome.

3

here is a cool link for you - Cell Size and Scale

use the slider bar at the bottom of the pic to magnify and look at things you described in your post.

4

Ha! Cool double posts.

5

So it looks like an X chromosome would be about the size of a car parked in the driveway, relatively speaking.

6

According to this, unraveled, the complete human genome is 1-2 metres long, but 2nm wide.

7

Doesn’t leave much room for anything else–like 45 or 46 more chromosomes and assorted organelles. Fascinating. Well at least they shouldn’t be too hard to find.

8

That X chromosome seems out of scale to me. It’s essentially the same size as the skin cell’s nucleus or the entire head of the sperm, but it’s only about 2% of a human’s total DNA.

9

I think that’s a chromosome as it appears right before mitosis, when they’re most easily seen (and at which point they do rather dominate the contents of a cell). Most times, they’re not nearly so puffed up.

10

So…X chromosomes get puffy sometimes? Gotta be careful making remarks like that, dude.

11

This can’t be right. According to that graphic, one chromosome is longer than the nucleus is wide and almost as tall. Since there are 46 chromosomes in the nucleus, that simply can’t be correct.

12

Keep in mind that the diagram linked by Telemark shows a chromosome* in a dividing cell, when the DNA has been all reeled up so it can be neatly moved around. The DNA has been coiled around itself, kind of like a telephone cord, but it’s still flexible; so yes, it can be longer than the nucleus and still fit (in its un-compacted state, the X chromosome is on the order of about 3 inches long, depending on what set of numbers you use to estimate base pairs = physical length).

Here’s a short video of the DNA of a dividing cell just at the point of division. The DNA has been replicated and the chromosomes have already been reeled up; first they jiggle around a bit as the connection points get lined up at the division plane, and then the two copies get pulled apart. As you can see the DNA is quite flexible. And after they’ve been separated the chromosomes quickly unravel and go back to their normal un-compacted state (the movie ends before the nucleus completely reforms and before the cell itself divides).

  • actually it shows two copies of a chromosome, after the DNA has been replicated; they’re linked together by the “cross” on the X to keep them paired up until cell division happens.
13

Thanks for that link; I knew I’d seen good videos of the process, but I couldn’t find any of them on my search (I was mostly finding animations).