Deoxyribonucleotide
Definition
The monomer unit of DNA, consisting of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases (adenine, thymine, guanine, or cytosine). Nucleotides are linked by phosphodiester bonds between the 3' carbon of one sugar and the 5' carbon of the next.
- Components
- Deoxyribose sugar, phosphate group, nitrogenous base
- Bases
- Adenine, thymine, guanine, cytosine
- Linkage
- Phosphodiester bond, 3' to 5' carbon
- Role
- Monomer unit of the DNA polymer
Common questions
How does a deoxyribonucleotide differ from a ribonucleotide?+
A deoxyribonucleotide's sugar lacks the hydroxyl group present at the 2' carbon of ribose in RNA, and DNA uses thymine where RNA uses uracil. These differences make the DNA polymer more chemically stable, which is part of why it is the molecule sequenced in forensic profiling.
Why does the 3' to 5' linkage direction matter in forensic DNA testing?+
PCR primers and sequencing reactions extend a new strand only in the 5' to 3' direction, so the fixed directionality of the phosphodiester backbone determines how primers are designed and how STR amplification proceeds during profiling.
Related terms
- Antiparallel Orientation
- The two strands of the DNA double helix run in opposite directions: one strand reads 5' to 3', its complement reads 3'...
- Base Complementarity
- The specific pairing rules that govern double-stranded DNA: adenine pairs with thymine (2 hydrogen bonds) and guanine pairs with cytosine (3 hydrogen...
- Denaturation
- The separation of double-stranded DNA into two single strands by disrupting the hydrogen bonds between base pairs. In PCR, denaturation is achieved...
- GC Content
- The proportion of base pairs in a DNA molecule that are guanine-cytosine. Because G-C pairs form three hydrogen bonds (versus two for...
- Phosphodiester Backbone
- The repeating sugar-phosphate chain that forms the structural scaffold of each DNA strand. The backbone is highly charged and hydrophilic, faces outward...