Chapter 8.1: Nucleic Acids – The “Basics”
CHEM 7784
Biochemistry
Professor Bensley
CHAPTER 8.1 Nucleic Acid Basics
– Biological function of nucleotides and nucleic acids– Structures of common nucleotides
Today’s Objective: (To learn and understand the)
Central Dogma of Biology
Nucleotides and Nucleosides
• Nucleobase = Nitrogeneous base
• Nucleoside = Nitrogeneous base + Pentose
• Nucleotide = Nitrogeneous base + Pentose + Phosphate
Pentoses of Nucleotides
• D-ribose (in RNA)
• 2-deoxy-D-ribose (in DNA)
• The difference?
2'-OH vs 2'-H
• This difference affects secondary structure and stability
Nitrogenous Bases
Nucleosides
Anti-conformation predominates in nucleic acid polymers
Phosphate group
• Negatively charged at neutral pH
• Typically attached to 5’ position
–Nucleic acids are built using 5’-triphosphates
–Nucleic acids contain one phosphate moiety per nucleotide
Nucleotides• Phosphate ester of nucleosides
The plane of the base is oriented perpendicular to the plane of the pentose group
Nomenclature
Nomenclature: Deoxyribonucleotides
You need to know structures, names and symbols (both two-letter (dA) and four-letter (dAMP) codes)
Nomenclature: Ribonucleotides
You need to know structures, names, and symbols (both one letter and three-letter codes)
Polynucleotides
Nucleotide monomers are joined by 3’-5’ phosphodiester linkages to form nucleic acid (polynucleotide) polymers
Base pairing evident in DNA compositions