Nitrogen and Phosphorous Containing Compounds Flashcards
which amino acid is not optically active?
glycine
which amino acid is not (S) and why?
cysteine, change in priority caused by sulfur in its r group
describe amino acid’s acidic/basic character?
amphoteric
acidic carboxyl group and basic amino group
when an aa is put into soln it will become a ___________.
zwitterion
what are the pathways to form amino acids?
strecker and gabriel synthesis
describe the strecker synthesis
- starts w: aldehyde, ammonium chloride, and KCN
- forms racemic mixture
- performed in aq acid and accelerated by heat
Step 1
- carboxyl oxy protonated, electrophilicity inc
- ammonia attacks, imine formed
- CN- attacks forming nitrile group
- aminonitrile group formed
Step 2
- nitrile N protonated, electrophilicity inc
- attacked by two eq water
- carbonyl formed and ammonia kicked off
describe the gabriel synthesis
starts w: potassium phthalimide and diethyl bromomalonate
SN2
phthalimide begins as nucleophilic anion in soln
carbon electrophile
bromine is LG
Gabriel synthesis starts w planar molecule, product is racemic mixture
which type of bond links the nucleotide sugars in DNA?
phosphodiester bonds
describe the formation of phosphodiester bonds
DNA polymerase
ester dimer of phosphate (pyrophosphate) released
energetically funds phosphodiester bond formation
pyrophosphate can the. be hydrolyzed to be used for nucleotide formation (organic phosphates)
what is unique about the hydrogens of phosphoric acid?
each have their own pKa
predominant form of phosphoric acid
H3PO4
mildly acidic, weakly basic, and strongly basic soln phosphoric acids and the pKas needed to eliminate respective hydrogens
H2PO4- : 2.15
HPO4 2- : 7.20
PO4 3- : 12.32
At physiological pH of 7.4, the predominant form of phosphoric acid is…
dihydrogen phosphate and hydrogen phosphate
