Microbial Metabolism and Nutrient Transport

Vocabulary flashcards covering general metabolism, nutrient transport systems, nutritional/energy classes of microorganisms, bioenergetics, redox reactions, catabolic pathways, and biosynthesis.

Metabolism

The series of biochemical reactions by which the cell breaks down or biosynthesizes various metabolites.

Macronutrients

Nutrients that are required in large amounts.

Micronutrients

Nutrients that are required in minute amounts (e.g., trace elements as co-factors of certain enzymes, and iron (Fe) which plays a major role in cellular respiration).

Vitamins

Organic micronutrients that function as growth factors.

Active Transport

An energy-requiring process driven by ATP (or some other energy-rich compound) or by the proton motive force to accumulate solutes against the concentration gradient.

Simple Transport

Transport reactions driven by the energy inherent in the proton motive force.

Symport Reactions

Simple transport reactions where a solute and a proton are cotransported in one direction.

Antiport Reactions

Simple transport reactions where a solute and a proton are transported in opposite directions.

Group Transformation

A transport system where (1) the transported substance is chemically modified during the transport process, and (2) an energy-rich organic compound (rather than the proton motive force) drives the transport event.

ABC Transport Systems

Transport systems named after "ATP-binding cassette" (a structural feature of proteins that bind ATP) that employ a periplasmic binding protein along with transmembrane and ATP-hydrolyzing components.

Catabolism

Energy-yielding reactions.

Chemotrophs

Organisms that conserve energy from chemicals.

Chemoorganotrophs

Chemotrophs that use organic chemicals as their electron donors.

Chemolithotrophs

Chemotrophs that use inorganic chemicals as their electron donors.

Phototrophic Organisms

Organisms that convert light energy into chemical energy (ATP), including both oxygenic and anoxygenic species.

Heterotroph

An organism whose cell carbon is obtained from one or another organic compound.

Autotroph

An organism that uses carbon dioxide ($CO_2$) as its carbon source.

Primary Producers

Autotrophs (most chemolithotrophs and phototrophs) because they synthesize new organic matter from inorganic carbon ($CO_2$).

Calvin Cycle

The major biochemical pathway by which phototrophic organisms incorporate $CO_2$ into cell material.

Enzymes

Protein catalysts that increase the rate of biochemical reactions by activating the substrates that bind to their active site.

$$\Delta G^0$$

A measure of the energy released or consumed in a reaction under standard conditions, which reveals which reactions can be used by an organism to conserve energy.

Reduction Potential ($E_0^\prime$)

The tendency of a compound to accept or release electrons.

ATP (Adenosine Triphosphate)

The prime energy carrier in the cell, consisting of a ribonucleoside to which three phosphate molecules are bonded in series.

Embden-Meyerhof-Parnas Pathway (Glycolysis)

The universal pathway for the catabolism of glucose, used to break down glucose to pyruvate as a widespread mechanism for energy conservation by fermentative anaerobes via substrate-level phosphorylation.

Citric Acid Cycle

The pathway by which pyruvate is oxidized to $CO_2$, generating $CO_2$ and electrons for the electron transport chain.

Glyoxylate Cycle

A cycle necessary for the catabolism of two-carbon electron donors, such as acetate.

Electron Transport Chains

Chains composed of membrane-associated redox proteins arranged in order of increasing $E_0^\prime$ values, functioning to carry electrons from the primary electron donor to the terminal electron acceptor ($O_2$ in aerobic respiration).

Gluconeogenesis

The production of glucose from non-sugar precursors.