Biochemistry

Chapter 1: Amino Acids, Peptides, & Proteins

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Amino acids have four groups attached to a c____arbon.

Four groups attached to an amino acid are: ____, and {{1::an R group}}.

The ____ group determines chemistry and function of an amino acid.

The R group determines ____ of an amino acid.

____ amino acids appear in the proteins of eukaryotic organisms.

The stereochemistry of the α -carbon is ____ for all chiral amino acids in eukaryotes.

____-amino acids can exist in prokaryotes.

All chiral amino acids except ____ have (R or S) configuration.

All chiral amino acids except cysteine have (____) configuration.

All amino acids are chiral except ____, which has a hydrogen atom as its R group.

All amino acids are chiral except glycine, which has a ____s its R group.

Amino acid side chains can be ____.

Nonpolar, Nonaromatic Amino Acids:

Aromatic Amino Acids:

Polar Amino Acids:

Negatively Charged (Acidic) Amino Acids: - ____

Positively Charged (Basic) Amino Acids:

Amino acids with ____ are hydrophobic.

Amino acids with long alkyl chains are ____.

Amino acids with charges are ____.

Amino acids with ____ are hydrophilic.

Essential amino acids ____ be made by the body.

____ amino acids cannot be made by the body.

Essential Amino Acids:

____ is only an essential amino acid during (+) nitrogen balance.

Arginine is only an essential amino acid ____

Arginine is only a____mino acid during (+) nitrogen balance.

Hydrophillic Amino Acids:

Amino acids are amphoteric; that is, ____.

Amino acids are ____; that is, they can accept or donate protons.

The ____ of a group is the pH at which half of the species are deprotonated.

The p K a of a group is ____.

At ____ pH, the amino acid is fully protonated.

At low (acidic) pH, the amino acid is ____.

At ____ pH, the amino acid is a neutral zwitterion.

At near the pI of pH, the amino acid is ____.

At ____ pH, the amino acid is fully deprotonated.

At high (alkaline) pH, the amino acid is ____.

The ____ of an amino acid without a charged side chain can be calculated by averaging the two p K a values.

The isoelectric point (pI) of an amino acid without a charged side chain can be calculated by ____.

The titration curve is nearly ____ at the p K a values of the amino acid.

The titration curve is nearly flat at the ____ values of the amino acid.

The titration curve is nearly ____ at the pI values of the amino acid.

The titration curve is nearly vertical at the ____ values of the amino acid.

Amino acids with ____ have an additional p K a value.

Amino acids with charged side chains have ____

Amino acids with charged side chains, their pI is calculated by ____.

Amino acids without charged side chains have a pI around ____.

Acidic amino acids have a pI ____

Basic amino acids have a pI ____

Dipeptides have ____ amino acid residues.

Tripeptides have ____ amino acid residues.

Oligopeptides have a ____ amino acid residues.

____ have a “few” (<20) amino acid residues.

Polypeptides have ____ amino acid residues.

____ have “many” (> 20) amino acid residues.

Forming a peptide bond is a ____ reaction.

The ____ attacks the electrophilic carbonyl group of another amino acid, to form a peptide bond.

The nucleophilic amino group of one amino acid attacks the ____ of another amino acid, to form a peptide bond.

Amide bonds are ____ because of resonance.

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