Flashcards in Organic Chemistry Chapter 10: Nitrogen and Phosphorus-Containing Compounds Deck (23)
The a-carbon of an amino acid is attached to
an amino group
a carboxyl group
a hydrogen atom
a R group
All amino acids are chiral, except
All amino acids in eukaryotes are L or D?
What is the only amino acid that does not have S stereochemistry?
cysteine - R
they can act as acids or bases -- amino acids
Nonpolar nonaromatic amino acids
alanine, valine, leucine, isoleucine, isoleucine, glycine, proline and methionine _ tend to be hydrophobic
Aromatic amino acids
tryptophan, phenylalanine, tyrosine _ tend to be hydrophobic
Polar amino acids
serine, threonine, asparagine, glutamine and cysteine _ tend to be hydrophilic
Negatively charged amino acids
contain carboxylic acids in their R groups and include aspartic acid and glutamic acid _ tend to be hydrophilic
Positively charged amino acids
contain amines in the R groups and include arginine, lysine and histidine _ tend to be hydrophilic
Peptide bonds form by _ and can be cleaved by __
Formed by condensation -- cleaved by hydrolytically
What is needed to cleave a peptide bond?
strong acid or base
What restricts motion about the C-N bond in a peptide bond?
resonance of the peptide bond
Strings of amino acids
What are two ways to synthesize amino acids in the lab?
Stecker synthesis - from an aldehyde
Gabriel synthesis - from potassium phthalimide, diethyl bromomalonate and an alkyl halide
1. Aldehyde is mixed with ammonium chloride and potassium cyanide. The ammonia attacks the carbonyl carbon, generating and imine.
2. Imine is then attacked by the cyanide, generating an aminonitrile.
3. Aminonitrile is hydrolyzed by two equivalents of water, generating an amino acid.
1. Phthalimide attacks the diethyl bromomalonate, generating a phthalimalonic ester
2. The phthalimidolmalonic ester attacks an alkyl halide, adding an alkyl group to the ester
3. The product is hydrolyzed, creating phthalic acid (with two carboxyl groups) and converting the esters into carboxylic acids.
4. One carbozylic acid of the resulting 1,3-dicarbonyl is removed by decarboxylation
Phosphorus is found in
Inorganix phosphate, a buffered mixture of hydrogen phosphate and dihydrogen phosphate
What is the bond in the backbone of DNA? What is released when it forms
Phosphodiester bonds - pyrophosphate is released
Why are phosphate bonds high energy?
large negative charges in adjacent phosphate groups and resonance stabilization of phosphates.
are carbon-containing compounds that also have phosphate groups. The most noteable examples are ATP and DNA