Chapter one Flashcards
Amino acid
Contains two functional groups.
- Amino group (NH2)
- Carboxyl group (-COOH)
Alpha amino acid
Has the amino group and carboxyl group bonded to the same carbon. There are 20 alpha amino acids that are encoded by the human genetic code, known as proteinogenic amino acids.
Chirality in amino acids
The alpha carbon is chiral meaning it has four groups attached. Because of this, most amino acids are optically active.
The ONLY exception to chirality in amino acids is glycine, which has a hydrogen atom as one R group. This makes it achiral.
L-amino acids
All amino acids used in eukaryotes are L-amino acids. This means that they have a (S) absolute configuration.
The only exception to this is cysteine, which has an (R) configuration.
Non-polar, non-aromatic side chains
SEVEN AMINO ACIDS
- glycine (smallest)
- alanine
- valine
- leucine
- isoleucine
- methionine
- proline
Aromatic side chains
THREE AMINO ACIDS
- tryptophan
- phenylaline
- tyrosine
Polar side chains (NOT aromatic)
FIVE AMINO ACIDS
- serine
- threonine
- asparagine
- glutamine
- cysteine
Negatively charged acidic side chains
TWO AMINO ACIDS
- aspartic acid (aspartate)
- glutamic acid (glutamate)
Positively charged basic side chains
THREE AMINO ACIDS
- lysine
- arginine
- histidine
Hydrophobic amino acids
The amino acids with long alkyl side chains. Includes alanine, isoleucine, leucine, valine, and phenylalanine.
Hydrophilic amino acids
The amino acids with charged side chains. This includes positive ones (histidine, arginine, and lysine) and negative ones (glutamate and aspartate)
Alanine
- non-polar, non-aromatic side chain
- have an alkyl side chain containing one carbon
- Ala, A
Arginine
- positively charged, basic side chain
- has three Nitrogen atoms with delocalized positive charge
- Arg, R
Asparagine
- non-aromatic, polar side chain
- has an amide side chain
- do not change with pH
- Asn, N
Aspartic acid
- negatively charged, acidic side chain
- has carboxylate (-COO-)
- Asp, D
