Amino Acids, Proteins, and Enzymes Flashcards

Flashcards covering key concepts related to amino acids, proteins, and enzymes.

α-Amino acids are __.

Basic structural units of proteins that differ only in the side chain R group.

__ are formed by binding amino acids together through an amide linkage.

Formed by binding amino acids together through an amide linkage.

Proteins are classified based on __.

Enzyme catalysts, structural proteins, contractile proteins, hormones and transfer proteins

Globular proteins are __.

Spherical or ellipsoidal resulting from folding of the polypeptide chain(s) on itself.

Fibrous proteins are __.

Rod-shaped molecules containing twisted linear polypeptide chains.

Primary Structure is __.

The linear sequence in which the constituent amino acids are covalently linked through amide bonds, also known as peptide bonds.

Secondary Structure is __.

The periodic spatial arrangement of amino acid residues at certain segments of the polypeptide chain.

Tertiary Structure is __.

The spatial arrangement attained when a linear protein chain with secondary structure segments folds further into a compact three-dimensional form.

Quaternary Structure is __.

The spatial arrangement of a protein when it contains more than one polypeptide chain.

Denaturation of a protein involves __.

Major changes in the secondary, tertiary, and quaternary structures without cleavage of backbone peptide bonds.

Water molecules bind to several groups in proteins including __.

Charged groups, backbone peptide groups, amide groups of Asn and Gln, and hydroxyl groups of Ser, Thr, Tyr residues

Protein solubility affects __.

Thickening, foaming, emulsifying, and gelling properties

Texturization is __.

Transformation from a globular state to a fibrous physical structure with meat-like mouthfeel characteristics.

Protein quality is __.

Related mainly to essential amino acids content and digestibility.

Digestibility refers to __.

Bioavailability or the extent to which amino acids are utilized in the body.

Antinutritional factors include __.

Trypsin and chymotrypsin inhibitors, lectins

Protein modification is __.

Altering the molecular structure or a few chemical groups of a protein to improve their techno-functionality and bioactivity.

Enzymatic modifications of proteins/enzymes include __.

Glycosylation, Hydroxylation, Phosphorylation, Methylation, Acylation and cross-linking

Enzymes __.

Are proteins (or mostly proteins), are biochemical catalysts, and exhibit selectivity towards substrates.

Factors that affect enzyme activity include __.

Temperature, pH, substrate concentration, activators (cofactors or coenzymes), and inhibitors

Alpha-amylase __.

Hydrolyze starch alpha-1-4 glycosidic bonds within starch to dextrins, maltose and maltotriose

Invertase __.

Hydrolyze glycosidic bond between glucose and fructose in sucrose.

Lactase __.

Hydrolyzes the glycosidic bond between galactose and glucose in lactose.

Proteases __.

Hydrolyze peptide bonds in proteins and can be used as a meat tenderizer.

Chymosin (rennin) __.

Hydrolyzes kappa casein

Lipases __.

Hydrolyze ester bonds between fatty acids and a glycerol molecule and can lead to hydrolytic rancidity.

Polyphenol oxidase (PPO) __.

Catalyzes oxidation of phenolic compounds in the presence of O2 to give quinones which polymerize into melanin pigments.