Nucleotide Structure: Pentose sugar

Nucleotide Structure: Nitrogenous Bases

DNA Linkage• Phosphate group/phosphodiester bond• Nucleotides contain one, two, or three

phosphate groups*nucleoside *nucleotide

Nucleic Acid Polarity*Top of molecule hasfree 5’-phosphate

group

This is the 5’ end

*Bottom has a free 3’hydroxyl group

This is the 3’ end

*Early 1950’s Rosalind Franklin

*1953 Watson and Crick

Structural analysis of DNA

Complementarity

DNA Structure:

Alternative Forms of DNA

G + C Content

DNA Melting*Temperature at which DNA strands are ½ denatured is

the melting temperature or Tm

*GC content of DNA has a significant effect on Tm