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DNA Structure - Overview
DNA
- Deoxyribunucleic acid
- Linear polymer of nucleotide monomers
- Stores genetic information
- Fixed backbone of sugar-phosphate units (component of nucleotides)
- 2 strands of complementary and antiparallel DNA come together to form a double helix.
Nucleotide
- Monomer of DNA
- 1 deoxyribose + 1 to 3 phosphate groups + 1 nitrogenous base
- 4 nitrogenous bases: Adenine, Thymine, Cytosine, Guanosine
Purines
- Adenine and Guanine
- Double-ringed nucleotides
Pyrimidine
- Thymine and Cytosine
- Single-ring nucleotides
- 1 phosphate between nucleotides
- Deoxyribose (or RNA ribose): nitrogenous base at C1, phosphate at C5, C3 has free -OH
- 5' end is the end: free phosphate group
- 3' end: free hydroxyl group
Base pairing
- Adenine-Thymine
- Guanine-Cytosine
- Generates the two-stranded, double helix structure of DNA