BCHM 218 Study Guide - Quiz Guide: Royal Naval Air Service, Northern Blot, Gc-Content
7 Dec 2015
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Base characteristics: nucleotides are molecules consisting of: Phosphate group (without this it is a nucleoside: nucleotides are either. Purines: two cyclic components; adenosine and guanine; puckered. Pyrimidines: cytosine, thymine and uracil; planar: dna: 2"-deoxy-d-ribose, rna: d-ribose, nucleotides can also be methylated. Methylated nucleotides often have roles in regulating or protecting genetic information. Phosphodiester backbone: successive nucleotides are covalently joined by phosphate groups. Give directionality; 5" phosphate or 3" hydroxyl: hydrophilic, negatively charged @ ph7. Often neutralized by ionic interactions with metal cations: dna backbone is more stable and less susceptible to hydrolysis in alkaline conditions, oligonucleotides: short nucleic acids (<50 bases, polynucleotides: long nucleic acids (>50 bases) Affects of nucleotides on dna structure: due to delocalized electrons in the conjugated rings, they absorb uv light at 260nm. Used to detect nucleic acids: hydrophobic stacking: bases align in stack to reduce contact with water. Combination of van der waals and electrostatic interactions: base pairing: results from hbonds between bases.
