Chapter 5: Microbial Metabolism

Cytochromes

________ are proteins with an iron- containing group (heme) capable of existing alternately as a reduced form (Fe2+) and an oxidized form (Fe3+)

Flavoproteins

________ contain flavin, a coenzyme derived from riboflavin (vitamin B2), and are capable of performing alter- nating oxidations and reductions.

Phototrophs

________ use light as their primary energy source, whereas chemotrophs depend on oxidation- reduction reactions of inorganic or organic com- pounds for energy.

Saprophytes

________ live on dead organic matter, and parasites derive nutrients from a living host.

Chemoheterotrophs

________ spe- cifically use the electrons from hydrogen atoms in organic compounds as their energy source.

cyclic photophosphorylation

In ________, the elec- trons released from chlorophyll in the photosystem 1 eventually return to chlorophyll.

noncyclic photo

In ________- phosphorylation, which is used in oxygenic organisms, both photosystems are required.

Oxidation

________ is the removal of electrons (e−) from an atom or mol- ecule, a reaction that often produces energy.

cofac

If the ________- tor is an organic molecule, it is called a coenzyme.

nonprotein component

Although some enzymes consist entirely of proteins, most consist of both a protein portion, called an apoenzyme, and a(n) ________, called a cofactor.

Reduction

________ means the molecule has gained one or more electrons.

Photosynthesis

________ takes place in two stages.

Alcohol fermentation

________ also begins with the glycolysis of a mol- ecule of glucose to yield two molecules of pyruvic acid and two molecules of ATP.

Photoheterotrophs

________ use light as a source of energy but can- not convert carbon dioxide to sugar; rather, they use organic compounds, such as alcohols, fatty acids, other organic acids, and carbohydrates, as sources of carbon.

Anabolism

________ is the building of complex organic mol- ecules from simpler ones.

Chemoautotrophs

________ use the electrons from reduced inorganic compounds as a source of energy, and they use CO2 as their principal source of carbon.

Catabolism

________ is the breakdown of complex organic compounds into simpler ones.

apoenzyme

Together, the ________ and cofactor form a holoenzyme, or whole, active enzyme.

Saturation

________ is when an enzymes active site is always occupied by substrate or product molecules, and its catalyzing a specific reaction at its maximum rate.

metabolic reactions

In some ________, sev- eral steps are required for the synthesis of a particular chemical compound, called the end- product.

Chlorophyll

________ and other pigments are packed into thylakoids of chloroplasts and are called photosystems.

Photophosphorylation

________ is one of the three ways ATP is formed, and it occurs only in photosynthetic cells.

Glycolysis

________ is the oxidation of glucose to pyruvic acid, and is usually the first stage in carbohydrate catabolism.

electron transport chain

A(n) ________ (electron transport system) consists of a sequence of carrier molecules that are capable of oxidation and reduction.

pentose phosphate pathway

The ________ (or hexose monophosphate shunt) operates simultaneously with glycolysis and provides a means for the breakdown of five- carbon sugars (pentoses) as well as glucose.

Competitive inhibitors

________ fill the active site of an enzyme and compete with the nor- mal substrate for the active site.

Carbohydrate catabolism

________, the break- down of carbohydrate molecules to produce energy, is therefore of great importance in cell metabolism.

Metabolic

________ pathways that function in both anabolism and catabolism are called amphibolic pathways, meaning that they are dual- purpose.

Noncompetitive inhibitors

________ do not compete with the substrate for the enzymes active site; instead, they interact with another part of the enzyme.

sequence of electron carriers

The ________ used in oxidative phosphorylation is called an electron transport chain (system)

Krebs cycle

The ________, also called the tricarboxylic acid (TCA) cycle or citric acid cycle, is a series of biochemical reac- tions in which the large amount of potential chemical energy stored in acetyl CoA is released step by step.