nucleic acid structure Flashcards
nucleoside
sugar + base
nucleotide
sugar + base + phosphate
where are new nucleotides added
3’ OH group
key difference between RNA and DNA
DNA only has a hydroxyl (OH) group at the 3’ carbon, while RNA has a hydroxyl at the 3’ AND the 2’
difference between uracil and thymine
thymine has a CH3 group at (if think) the 2’ carbon where uracil only has an H
what is required for the polymerization of DNA/RNA
requires an enzyme DNA or RNA polymerase
requires a form of energy - ATP, CTP, GTP, TTP
why are triphosphates high in energy
binding of 3 phosphates is unfavourable, w/ 3 negative ions in close proximity, removing the outermost releases energy which can be used to like nucleotide monomers to the polymer (nucleic acid)
number of hydrogen bonds between A and T
2
number of hydrogen bonds between C and G
3
DNA primary level of structure
single strand of dna - nucleotide sequence - phosphodiester bonds
DNA secondary level of structure
DNA double helix - hydrogen bonds
DNA tertiary structure
helix winds to form chromatin/chromosomes
purine bases
adenine and guanine, bigger
pyrimidine bases
thymine and cytosine, smaller
why is watson-crick base pairing good?
correct geometry - same distance between bases in the strands
allows for base stacking to improve stability
no bulging and bases are close enough to for nc interactions
