Chapter 16: Amino Acids, Proteins, and Enzymes

It provides structural components.

It makes muscle moves.

They carry essential substances throughout the body

They store nutrients.

They regulate body metabolism and the nervous system.

They catalyze biochemical reactions in the cells.

They recognize and destroy protein substances.

These are the molecular building blocks of proteins.

The pH at which an amino acid exists in an ionized form with an overall net charge of zero.

These acids have hydrogen, alkyl, or aromatic R groups, which make them hydrophobic.

These acids have R groups that interact with water, which makes them hydrophilic.

The R group of a polar ______ contains a carboxylate group

The R group of a polar _____ contains an amino group, which ionizes to give an ammonium ion.

An amino acid with positive and negative charges and thus an overall neutral charge forms only at a certain pH called the _____.

The pI values for nonpolar and polar neutral amino acids are from pH _______.

The pI values of the acidic amino acids are around ____, and the carboxylic acid group in the R groups is not ionized.

The pI values of basic amino acids are typically higher than physiological pH values, ranging from ____.

An amide bond forms when the —COO- group of one amino acid reacts with the —NH3+ group of the next amino acid.

The linking of two or more amino acids by peptide bonds forms a _____.

Two amino acids form this.

Three amino acids form this.

Four amino acids form this.

A chain of five amino acids form this.

A chain of multiple amino acids.

The particular sequence of amino acids is held together by peptide bonds.

The first protein to have its primary structure determined was ____, which was accomplished by Frederick Sanger in 1953.

The first protein to have its primary structure determined was insulin, which was accomplished by __________ in 1953.

This structure describes the type of structure that forms when amino acids form hydrogen bonds within a polypeptide or between polypeptide chains.

In an _____, hydrogen bonds form between the oxygen of the C=O groups and the hydrogen of N—H groups of the amide bonds in the next turn of the ɑ helix.

In a _____, hydrogen bonds form between the oxygen atoms in the carbonyl groups in one section of the polypeptide chain and the hydrogen atoms in the N—H groups of the amide bonds in a nearby section of the polypeptide chain.

It makes up as much as one-third of all proteins in vertebrates. It is found in connective tissue, blood vessels, skin, tendons, ligaments, the cornea of the eye, and cartilage.

The strong structure of collagen is a result of three polypeptides woven together like a braid to form a _____.

The folding of the secondary structure of a protein into a compact structure that is stabilized by the interactions of R groups.

These are interactions between two nonpolar amino acids that have nonpolar R groups.

These are attractions between the external aqueous environment and the R groups of polar amino acids that are pulled to the outer surface of globular proteins where they form hydrogen bonds with water.

These are ionic bonds between ionized R groups of basic and acidic amino acids.

These form between the H of a polar R group and the O or N of another amino acid.

These are covalent bonds that form between the —SH groups of cysteines in a polypeptide chain.

A protein structure in which two or more protein subunits form an active protein

A globular protein that transports oxygen in the blood, consists of four polypeptide chains.

two 𝛼-chains of hemoglobin has ______ amino acids.

two 𝜷-chains of hemoglobin has ______ amino acids.

A single polypeptide chain with a molar mass of 17 000, has about one-fourth the molar mass of hemoglobin.

Group of proteins that have e compact, spherical shapes because sections of the polypeptide chain fold over on top of each other due to the various interactions between R groups.

These are proteins that consist of long, thin, fiber-like shapes. They are typically involved in the structure of cells and tissues.

These are the proteins that makeup hair, wool, skin, and nails. In hair, three helices coil together like a braid to form a fibril.

These are the type of proteins found in the feathers of birds and scales of reptiles.

• It occurs when there is a change that disrupts the interactions that stabilize the secondary, tertiary, or quaternary structure.

• It also occurs by adding certain organic compounds or heavy metal ions or by mechanical agitation.

These are biological catalysts that are needed for most chemical reactions that take place in the body.

It increases the reaction rate by changing the way a reaction takes place but is itself not changed at the end of the reaction.

An _____ in a cell may take place eventually, but not at a rate fast enough for survival.

The molecule that reacts in the active site in an enzyme-catalyzed reaction.

A pocket in a part of the tertiary enzyme structure that binds substrate and catalyzes a reaction.

It is formed when there’s a combination of an enzyme and a substrate within the active site that provides an alternative pathway with lower activation energy.

• It described the active site as having a rigid, nonflexible shape.

• According to this theory, the shape of the active site was analogous to a lock, and its substrate was the key that specifically fit that lock.

• In the dynamic model of enzyme action, the flexibility of the active site allows it to adapt to the shape of the substrate.

• At the same time, the shape of the substrate may be modified to better fit the geometry of the active site.

These are for oxidation–reduction reactions.

_____ oxidize a substance.

____ reduce a substance.

_____ remove 2H atoms to form a double bond.

Transfer a group between two compounds.

____ transfer amino groups.

____ transfer phosphate groups.

For hydrolysis reactions.

They hydrolyze peptide bonds in proteins.

They hydrolyze ester bonds in lipids.

They hydrolyze glycosidic bonds in carbohydrates.

They hydrolyze phosphodiester bonds.

They hydrolyze nucleic acids.

Add or remove groups involving a double bond without hydrolysis.

Rearrange atoms in a molecule to form an isomer

_____ add CO2.

_____ remove NH3.

These convert cis to trans isomers or trans to cis isomers.

These convert D to L stereoisomers or L to D.

Form bonds between molecules using ATP energy.

These combine two molecules.

The ____ of an enzyme describes how fast an enzyme catalyzes the reaction that converts a substrate to a product.

Enzymes are most active at _______, which is 37 °C, or body temperature, for most enzymes.

Enzymes are most active at their ____, the pH that maintains the proper tertiary structure of the protein.

Kinds of molecules that cause enzymes to lose catalytic activity.

An enzyme with a _____ can regain enzymatic activity.

An enzyme attached to an ____ loses enzymatic activity permanently.

It has a chemical structure and polarity that is similar to that of the substrate.

It does not resemble the substrate and does not compete for the active site. It binds to a site on the enzyme that is not the active site.

a molecule causes an enzyme to lose all enzymatic activity. Most irreversible inhibitors are toxic substances that destroy enzymes.

It forms a covalent bond with an amino acid side group within the active site, which prevents the substrate from binding to the active site or prevents catalytic activity.