KEY TAKEAWAYS •
DNA is the genetic material in all cells but may not be the genetic material in viruses.
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A nucleotide has a nitrogenous base, a deoxyribose sugar, and a phosphate group.
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DNA is a double-stranded helix that has the nitrogenous bases making up the rungs of the ladder shape of the molecule.
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RNA contains a ribose sugar, is often single-stranded, contains uracil instead of thymine, and is generally less stable than DNA.
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The genome is the totality of the genes in a cell. A cell can be haploid, diploid, or polyploid, depending on the number of copies of DNA within the cell.
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