BIOCH 200 (January 15, 2014) - Nucleotides and Nucleic Acids
University of Alberta
BIOCH 200 Nucleotides and Nucleic Acids (con’t)
• *The most important factor in stabilizing the double helix structure of DNA are the
hydrophobic interactions that occur between the paired bases and water
o In single stranded DNA, the bases interact with water and no helical
structure is witnessed.
• Why does ssDNA absorb more UV light than dsDNA?
o *Since the bases of the single-stranded DNA are not linked to a
complementary base, they are less constrained than bases in double-
stranded DNA. Since ssDNA is less constrained it has more resonance
capabilities for electron delocalization than dsDNA.
• *(Correction for mistake in last set of notes) Generally, DNA (both kinds) have a
wavelength absorption ratio between 260nm:280nm of 2:1. If there is any protein
contamination, there would be more absorption of 280nm wavelengths of light
and therefore the ratio of 2 would decrease accordingly.
• Protein UV light absorption is due to side chains. Protein examples:
• *The cytosine uracil deamination reaction is an important reaction to remember!
• *An important characteristic of pyrimidine:
o They have 2 nitrogen atoms that are a part of the heterocyclic ring
• *Thymine + ribose = ribothymidine
o IT IS NOT thymidine. Thymidine is automatically assumed to the be = to
thymine + deoxyribose
Catabolic process – process of energy generation
Anabolic process – process of