Question

What shape does the DNA have?

Answer 1

DNA is in long strands so it doesn't have a specific shape, but if its just for you to understand, DNA looks like two laces twirled together or the Twizzlers candy

Answer 2

@sidm, +1 for the Twizzler analogy. :D

DNA's specific structure is actually highly regulated at all size scales.

At the molecular level, any of the nucleotides in DNA can sample a variety of similar but different conformations. Which subset of those conformations an individual nucleotide actually assumes when incorporated into the DNA depends on other bases near it in the sequence. This actual sequence affects the local structure of the DNA very much - for example poly A tracts containing lots of As on one strand and base paired to Ts on the other tend to adopt curved conformations.

At the canonical textbook level, DNA is probably most present as B-DNA; however, it can also form A-DNA, which is slightly wider, Z-DNA which is funky and possibly does not occur in living systems; four stranded complexes similar to a fireman's carry between poly-G tracts which have been proposed to occur at the ends of telomeres and a number of other structures which many or many not occur in living systems.

If left free in solution as in vitro, the DNA helix can exhibit both twist and writhe. Twist and writhe are different ends of the same topological continuum imposed by torsional strain. Think of writhe in context of a telephone cord which wraps itself in a circle many times and think of twist as what you'd get if you stretched the telephone cord out straight.

In vivo, DNA is organised into chromatin. Specifically, it wraps itself around complexes of proteins, called nucleosomes, which are made out of proteins called histones. The nucleosomes play important regulatory roles both in imposing higher structures on the chromatin (like ordering it into loops and eventually compacting it into chromosomes) and in regulating gene expression.

Answer 3

@blues thank youu :D