how many types of DNA?

[SheffieldWednesdayFC]

Hey everyone,

I was wondering about this: DNA coils up and makes a supercoiled solenoid chromosome. Does that mean each chromosome has 1 DNA strand? and for humans, does that mean we have 23 different types of DNA?

Thanks,

I can't believe I don't know this yet after 2nd year biology

[JackBean]

1) DNA is usually doublestranded
2) I think, that to be something solenoid, it must be circular, must it not? So, that's the case of bacterial or plasmid/mitochondrial chromosomes. The linear human chromosomes are packed a little bit else
3) question is, what you mean by type of DNA? If only separate strand, than yes, we have 23 different "types" of DNA. If you mean something distinguishable, than no, we have of course only one type of DNA, as do all organisms

[SheffieldWednesdayFC]

I was wondering if the DNA's coding sequence on one chromosome would be different than that on another chromosome.

Also, I was wondering if a chromosome was made from 1 DNA (double strand).

[JackBean]

Sure, that the sequence will differ. Why shall we have 23 copies of the same set of chromosomes?

Sure, that chromosome is made from 1 double stranded DNA