Concept 3.1 Nucleic Acids are Informational Macromolecules
Nucleic Acids are polymers specialized for storage, transmission, and use of genetic
DNA= deoxyribonucleic acid
RNA= ribonucleic acid
Nucleotide: Pentose sugar + N-containing base + phosphate group
Nucleosides: Pentose sugar + N-containing base
o Pyrimidines- single rings
o Purines- double rings
o DNA contains deoxyribose
o RNA contains ribose
Nucleotides have 3 components:
o Base (can be pyrimidines or purines)
o Ribose or deoxyribose
Nucleotides bond in condensation reactions to form phosphodiester linkages.
Nucleic acids grow in the 5′ to 3′ direction.
Oligonucleotides have about 20 monomers, and include small RNA molecules important
for DNA replication and gene expression.
DNA and RNA are polynucleotides, the longest polymers in the living world.
***Memorize Table 3.1 Distinguishing RNA from DNA***
Bases: Adenine, Cytosine, Guanine, Uracil
Bases: Adenine, Cytosine, Guanine, Thymine
Complementary base pairing:
o adenine and thymine
o always pair (A-T)
o double bonded
o cytosine and guanine
o always pair (C-G)
o triple bonded
Base pairs are linked by hydrogen bonds. There are so many hydrogen bonds in DNA and RNA that they form a fairly strong attraction,
but not as strong as covalent bonds.
Thus, base pairs can be separated with only a small amount of energy.
RNA is usually single-stranded, but may be folded into 3-D structures, by hydrogen bonding.
Folding occurs by complementary base pairing, so structure is determined by the order of
DNA—two polynucleotide strands form a “ladder” that twists into a double helix.
Sugar-phosphate groups form the sides of the ladder, the hydrogen-bonded bases form the