Biochemistry and Cellular Respiration: Key Concepts and Enzymes

Catabolism; Catabolic

__ is the metabolic breaking down of complex molecules into simpler substituents.

Anabolism; Anabolic

__ describes the metabolic building up of complex molecules from simpler substituents.

Exergonic

An __ reaction is one in which the products of the reaction have a lower level of free energy than the starting reactants.

Endergonic

An __ reaction is one in which the products of the reaction have a higher level of free energy than the starting reactants.

Energy coupling

In cells, the energy released in exergonic reactions is used to drive endergonic reactions in a process called __.

ATP

The molecule most commonly used to couple exergonic and endergonic reactions in both eukaryotic and prokaryotic cells is __.

-ase

Enzymes are (almost always) proteins that catalyze chemical reactions; they generally have names with the suffix ending __.

Induced Fit

The __ model describes the interaction of an enzyme and substrate in which binding leads to a shape change in the enzyme and a tighter interaction at the active site.

Energy of Activation

Even in chemically favorable reactions an energy barrier called the __ exists which significantly slows reaction rate in the absence of enzyme.

Transition state

The general mechanism by which enzymes catalyze chemical reactions is by stabilizing the energetically unfavorable __ between substrate and product.

Active Site

The region of an enzyme where substrate binds and catalysis occurs is called the __.

Cofactors

Trace minerals are required elements in the diet because they function as __ in enzymatic reactions.

Coenzymes

Organic molecules referred to as vitamins are required in the diet because they are either precursors for, or act directly as __ in enzymatic reactions.

Competitive Inhibition

The phenomenon wherein a substance binds to an enzyme at the active site and prevents substrate binding is called __.

Non- or Uncompetitive Inhibition

When a substance binds an enzyme at a region distant from the active site and disrupts catalysis, this is called __.

Allostery or allosteric regulation

The mechanism of enzymatic regulation in which a substance binds to an enzyme at a region distal to the active site and causes a shape change that either activates or inactivates catalysis is called __.

Cooperativity

The phenomenon wherein substrate binding to one subunit of a multisubunit enzyme leads to a shape change in the other subunits, causing a higher affinity for substrate is referred to as __.

Protein kinases

The class of enzymes that catalyzes transfer of a phosphate group to proteins is __.

Protein phosphatases

The class of enzymes that hydrolyzes a phosphate group from proteins is __.

Intermediary metabolism

The term that describes the existence of distinct metabolic pathways interconnected by common intermediates within the pathways is __.

Glycolysis

The stage of cellular respiration in which glucose is oxidized to form pyruvate is __.

Citric Acid Cycle

The stage of cellular respiration in which acetyl CoA is oxidized to form carbon dioxide is __.

Electon Transport Chain

The cluster of protein complexes in the inner mitochondrial membrane that establishes a proton gradient across the membrane is the __.

Substrate level phosphorylation

The synthesis of ATP by the direct transfer of a phosphate group from a higher energy phosphate containing molecule is called __.

Oxidative Phosphorylation

The synthesis of ATP that relies on proton flow across the inner mitochondrial membrane is called __.

Oxidation

A chemical reaction involving the loss of electrons or control over electrons is called __.

Reduction

A chemical reaction involving the gain of electrons or control over electrons is called __.

NAD+ (NADH)

The coenzyme that acts as a high energy electron carrier in redox reactions in both the citric acid cycle and glycolysis is __.

FAD (FADH2)

The coenzyme that acts as a high energy electron carrier in a redox reaction in the citric acid cycle, but not in glycolysis is __.

Hexokinase

The enzyme that catalyzes the phosphorylation of glucose in the first step of glycolysis is __.

Phosphofructokinase

The enzyme that catalyzes the phosphorylation of fructose 6-phosphate to form fructose 1,6 bisphosphate in glycolysis is __.

Cristae

The infoldings of the inner mitochondrial membrane are called __.

Matrix

The space enclosed by the inner mitochondrial membrane is the __ of the mitochondrion.

Intermembrane space

The space between the inner and outer mitochondrial membrane is called the __.

Proton Motive Force

The concentration gradient of hydrogen ions across the inner mitochondrial membrane is referred to as the __, a term that describes its capacity to provide the energy for ATP synthesis.

Chemiosmosis

The flow of hydrogen ions through ATP Synthase is referred to as __.

ATP Synthase

The enzyme that resides in the inner mitochondrial membrane and synthesizes ATP is called __.

Cellular Respiration

Describes the overall pathway that includes the reactions of glycolysis, the citric acid cycle, and oxidative phosphorylation.

citric acid cycle/Kreb's cycle

A metabolic pathway that occurs within mitochondria in which acetyl is oxidized to carbon dioxide (CO2).

Acetyl

When the three carbon compound pyruvate is oxidized, the reaction yields one molecule of carbon dioxide (a one carbon compound) and one molecule of ______ (a two carbon compound).

FAD/FADH2

The electron carrier that is used in the citric acid cycle, but not in glycolysis or pyruvate oxidation is ____.

Coenzyme A

The molecule that acetyl is attached to following pyruvate oxidation.

Fermentation

_____ is the process that regenerates NAD+ from NADH when oxygen is limiting, allowing glycolysis to continue to produce ATP.