Module 3: DNA structure/function Flashcards
Nucleic acids
polymeric macromolecules made of monomeric building blocks (nucleotides)
DNA structure
phosphate linked to sugar at C5 and sugar to base at C1
**H at C2 of sugar
RNA structure
phosphate linked to sugar at C5 and sugar to base at C1
**OH at C2 of sugar
Cytosine
pyrimidine -heterocyclic aromatic ring w 2 substituents attached: amino group (NH2) at C4 kept group (=O) at C2
3 HB w Guanine
Adenine
purine -heterocyclic aromatic organic compound containing pyrimidine ring fused w imidazole ring
2 HB w thymine/uracil
Uracil
pyrimidine -heterocyclic aromatic ring
2 HB w adenine
Thymine
pyrimidine -heterocyclic aromatic ring
2 HB w adenine
Guanine
purine -heterocyclic aromatic organic compound containing pyrimidine ring fused w imidazole ring
3 HB w cytosine
Phosphodiester bond
phosphate group attacked to hydroxyl at C5 of one monomer and hydroxyl on C3 of another
5’ end
free phosphate group
3’ end
free hydroxyl group
Making DNA polypeptides
coupling w dNTP
condensation reaction between the 3’ OH of the growing nucleotide chain and the 5’ hydroxyl of a deoxynucleoside monophosphate to produce a polynucleotide chain+1 and water (thermodynamically unfavourable)
Use dNTP -contains an energy packed triphosphate moiety at the 5’ end
(thermodynamically favorable)
DNA Double helix
hydrophilic phosphate-deoxyribose backbone outside, in contact w aq enviro
bps stacked through non-covalent Van der Waals interactions to hold
Major groove
more direct access to bases, primary site for pr- binding
Minor groove
faces sugar backbone, not typically used for pr- access
