Unformatted text preview: Figure 8 shows how two strands of nucleotides, paired by weak hydrogen bonds between the bases, form a double-stranded DNA. When bonded in this way, DNA forms a two-stranded spiral, or double helix. Note that adenine always bonds with thymine and cytosine always bonds with guanine. RNA differs from DNA in the following ways: • The sugar in the nucleotides that make an RNA molecule is ribose, not deoxyribose as it is in DNA. • The thymine nucleotide does not occur in RNA. It is replaced by uracil. When pairing of bases occurs in RNA, uracil (instead of thymine) pairs with adenine. • RNA is usually single-stranded and does not form a double helix as does DNA....
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This note was uploaded on 11/10/2011 for the course PT 101 taught by Professor Staff during the Spring '10 term at Texas State.
- Spring '10