Question: how many molecules are there in a single DNA?

Asked by ilikepie to Cindy, Katelin, Kate, Miranda, Yagiz on 13 Mar 2013.

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  1. Photo: Yagiz "Biohacker" Alp AksoyYagiz "Biohacker" Alp Aksoy
    answered on 13 Mar 2013:

    A DNA can be single-stranded, double-stranded, in some cases even triplex or quadruplex in structure. It could be linear or circular. It could exist in several alternate structural forms. So it is not possible to define it in terms of a fixed length as it could be a few nucleotides to the size that is packaged in entire length of a longest eukaryotic chromosome. However, DNA in the human genome is arranged into 24 distinct chromosomes (22 autosomes + X and Y chromosomes). Human genome is made up of 23 chromosome pairs with a total of ~3 billion DNA base pairs. Data comes out of human genome project suggests that we have 20,000 – 25,000 genes.

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  2. Photo: Miranda WeenMiranda Ween
    answered on 13 Mar 2013:

    DNA is made up of two strands of 4 nucleotides used over and over in different orders. (guanine, adenine, thymine, and cytosine) recorded using the letters G, A, T, and C. If one strand is GATCAGCT then the other strand opposite it will be CTAGTCGA as G always pairs with C and A always pairs with T.

    Depending on what the DNA is meant to tell the cell to make and do, is how long the sequence of nucleotide pairs will be

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  3. Photo: Kate SkulteKate Skulte
    answered on 13 Mar 2013:

    Just to add to the already great answers, the nucleotide which make up DNA are the repeating units of the DNA strands. Each nucleotide contains a ‘base’ the A, G, T and C Miranda mentioned, a sugar molecule and a phosphate group. The sugar and phosphate alternate to make a long strand and the A, T C and G are attached perpendicular to the sugar. When the two strands of DNA are next to each other is when you get the A meeting T and C meeting G.

    so you have three parts of the nucleotide which repeats along the entire length of the DNA 🙂

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