Flashcards in Organic Chemistry Chapter 10: Nitrogen and Phosphorus-Containing Compounds Deck (23)
1
The a-carbon of an amino acid is attached to
an amino group
a carboxyl group
a hydrogen atom
a R group
2
All amino acids are chiral, except
glycine
3
All amino acids in eukaryotes are L or D?
L
4
What is the only amino acid that does not have S stereochemistry?
cysteine - R
5
Amphoteric
they can act as acids or bases -- amino acids
6
Zwitterions
dipolar ions
7
Nonpolar nonaromatic amino acids
alanine, valine, leucine, isoleucine, isoleucine, glycine, proline and methionine _ tend to be hydrophobic
8
Aromatic amino acids
tryptophan, phenylalanine, tyrosine _ tend to be hydrophobic
9
Polar amino acids
serine, threonine, asparagine, glutamine and cysteine _ tend to be hydrophilic
10
Negatively charged amino acids
contain carboxylic acids in their R groups and include aspartic acid and glutamic acid _ tend to be hydrophilic
11
Positively charged amino acids
contain amines in the R groups and include arginine, lysine and histidine _ tend to be hydrophilic
12
Peptide bonds form by _ and can be cleaved by __
Formed by condensation -- cleaved by hydrolytically
13
What is needed to cleave a peptide bond?
strong acid or base
14
What restricts motion about the C-N bond in a peptide bond?
resonance of the peptide bond
15
Polypeptides
Strings of amino acids
16
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
17
Strecker synthesis
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.
18
Gabriel Synthesis
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
19
Phosphorus is found in
Inorganix phosphate, a buffered mixture of hydrogen phosphate and dihydrogen phosphate
20
What is the bond in the backbone of DNA? What is released when it forms
Phosphodiester bonds - pyrophosphate is released
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Why are phosphate bonds high energy?
large negative charges in adjacent phosphate groups and resonance stabilization of phosphates.
22
Organic phosphates
are carbon-containing compounds that also have phosphate groups. The most noteable examples are ATP and DNA
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