HBF 102 Lab 3: Proteins & Amino Acids Color Reactions

Macromolecules composed of amino acids linked by peptide bonds, forming the building blocks of life.

The unique sequence of amino acids in a protein chain, determining its primary structure.

The arrangement of the polypeptide chain into alpha-helices or beta-sheets, stabilized by hydrogen bonds. It's the first level of protein folding.

The three-dimensional structure of a protein, formed by the interactions between amino acid side chains. It's crucial for the protein's function.

The arrangement of multiple polypeptide chains (subunits) into a complex protein structure. It's the highest level of protein organization.

The process where a protein loses its native structure and function due to disruption of weak bonds and interactions.

Physical agents like heat, shaking, or UV radiation that can cause protein denaturation.

Chemical agents like acids, bases, or organic solvents that can disrupt protein structure and cause denaturation.

Color reactions used to identify and differentiate various proteins and amino acids based on their specific chemical properties.

The ability of a protein to absorb light at a specific wavelength, used to quantify protein concentration.

The presence of aromatic amino acids, like tyrosine and tryptophan in a protein sample.

A yellow precipitate forms in an acidic medium and then turns orange in an alkaline medium.

To detect the presence of sulfur-containing amino acids like cysteine and cystine.

Lead acetate reacts with sulfide ions to produce a brown to black precipitate.

The sulfur in methionine is not released by the treatment with NaOH, so methionine does not give a positive result.

A colorimetric test that detects the presence of peptide bonds.

Alkaline copper sulfate (CuSO4) is used in the Biuret reagent.

A violet color indicates a positive result in the Biuret test, signifying the presence of peptide bonds.

Proteins are made up of long chains of amino acids linked together by peptide bonds.

Globular proteins have a compact, spherical shape due to folding, while fibrous proteins have an elongated, fiber-like structure.

Proteins are large molecules with high molecular weights, usually exceeding 10,000 Daltons.

Proteins can act as both acids and bases due to the presence of amino and carboxyl groups in their structure.

The solubility of proteins is affected by pH. The lowest solubility occurs at the isoelectric point, while solubility increases in acidic or alkaline conditions.

Hydrolysis of proteins breaks them down into smaller peptides and amino acids, using either acids, bases, or enzymes called proteases.

Proteins can react with alcohols to form esters, which are compounds derived from organic acids.

Proteins can react with amines to form amides, which are nitrogen-containing compounds.

The Biuret test detects peptide bonds in proteins, forming a violet color when copper(II) ions bind to the nitrogen atoms.

The Ninhydrin test detects free α-amino groups in proteins, producing a bluish-purple color.

A chemical test used to detect the presence of proteins by forming a violet-colored complex with peptide bonds.

A colorimetric test that involves reacting a solution containing amino acids with ninhydrin to produce a purple-blue colored compound.

A chemical test used to detect the presence of tyrosine and tryptophan amino acids by forming a yellow-colored compound.

The specific color change observed in the Ninhydrin test indicating the presence of amino acids.

The test that indicates the presence of free amino acids, not just proteins.

The amino acid commonly detected in the Xanthoproteic test for its aromatic nature.

The reason why proline gives a yellow color in the ninhydrin test instead of the usual purple-blue.

The explanation for the positive result of aromatic amino acids in the Xanthoproteic test and not aliphatic ones.

An important functional group found in certain amino acids.

The key difference between cysteine and cystine.