Microbial Metabolism, Genetics, and Gene Transfer

Vocabulary practice flashcards covering microbial metabolism, gene regulation, DNA damage repair, horizontal gene transfer, and homologous recombination based on Chapters 7, 8, and 9 practice materials.

Anabolism

Metabolic reactions that build complex molecules from simpler ones.

Catabolism

Reactions that primarily function to release energy and supply materials and energy for anabolism.

Aerobic Respiration

A process involving the oxidation of glucose to generate ATP using oxygen as the final electron acceptor, yielding a maximum of $36\text{--}38\text{ ATP}$ per glucose molecule.

Glycolysis

A metabolic pathway common to almost all microorganisms that is included in aerobic respiration, anaerobic respiration, and fermentation.

$$\text{NAD}^+$$

A coenzyme that acts as an electron carrier in catabolic reactions.

NADH

An energy-rich electron carrier that stores energy in hydrogen atoms and electrons, yielding approximately $3\text{ ATP}$ upon entering the electron transport chain.

$$\text{FADH}_2$$

An electron carrier that enters the electron transport chain later than NADH and produces approximately $2\text{ ATP}$.

ATP (Adenosine Triphosphate)

A molecule that temporarily stores and releases energy released during exergonic reactions.

ATP Hydrolysis

The removal of the terminal phosphate from ATP to form $\text{ADP} + \text{P}_i$, releasing energy mainly used to drive biosynthesis and cellular work.

Fermentation

A metabolic process that does not use an electron transport chain, produces only $2\text{ ATP}$ per glucose, and uses organic molecules as final electron acceptors.

Anaerobic Respiration

A process that uses an electron transport chain where an inorganic compound like nitrate replaces oxygen as the final electron acceptor.

Enzymes

Proteins whose primary role in microbial metabolism is to increase reaction rates.

Electron Transport Chain

A membrane-associated system whose primary function is to transfer electrons sequentially and release energy to pump hydrogen ions ($\text{H}^+$) across the membrane.

Bacterial Electron Transport Chain Location

The cytoplasmic membrane.

Eukaryotic Electron Transport Chain Location

The inner mitochondrial membrane.

Proton Motive Force

An electrochemical gradient created when the electron transport chain pumps hydrogen ions ($\text{H}^+$) across the membrane.

ATP Synthase

A membrane protein structure through which hydrogen ions move back down their gradient, providing the energy to drive ATP synthesis.

Oxidative Phosphorylation

The metabolic process of coupling ATP synthesis to electron transport.

Wobble Hypothesis

A concept that explains flexibility in base pairing between codon and anticodon.

Anticodon

A nucleotide triplet located on tRNA that base pairs with a codon on mRNA.

Sigma Factor

A protein subunit that helps bacterial RNA polymerase recognize the promoter to begin transcription.

Bacterial Transcription and Translation Coupling

The simultaneous occurrence of transcription and translation made possible because bacteria lack a nucleus.

Repressible Operon

An operon that is usually ON and can be turned OFF, such as the trp operon.

trp Operon

A repressible operon that turns OFF when tryptophan levels are high, in which tryptophan functions as a corepressor.

lac Operon

An inducible operon that is most active when glucose is low and lactose is present.

lac Repressor Inactivation

The inactivation of the lac repressor caused by the binding of lactose.

Phase Variation

A regulatory mechanism that involves switching genes ON or OFF.

Housekeeping Genes

Genes expressed under many different conditions because their proteins perform basic functions needed by the cell.

Two-Component Regulatory System

A bacterial system that connects environmental signals directly to changes in gene expression.

Sensor Kinase

A transmembrane protein that detects external conditions and transmits the signal inside the cell by transferring a phosphate group to a response regulator.

Thymine Dimers

The primary form of DNA damage caused by exposure to UV radiation.

DNA Photolyase

An enzyme responsible for repairing UV-induced DNA damage using light.

Restriction Endonucleases

Bacterial enzymes produced to prevent the replication of an invading bacteriophage.

Conjugation

A mechanism of horizontal gene transfer requiring direct contact between bacterial cells via a sex pilus.

F Plasmid

A fertility plasmid involved in conjugation whose transfer from an $\text{F}^+$ donor converts an $\text{F}^-$ recipient into an $\text{F}^+$ cell.

Hfr Cell

A high-frequency recombination cell formed when the F plasmid integrates into the bacterial chromosome, enabling the transfer of chromosomal genes.

R Factor

A bacterial plasmid that carries genes conferring antibiotic resistance.

Transformation

A mechanism of horizontal gene transfer involving the uptake of free DNA from the environment, typically released from dead bacterial cells.

Competent Cell

A bacterial cell that is physiologically capable of taking up extracellular DNA.

Competence Factor (CF)

A signaling molecule that accumulates extracellularly as bacterial cell numbers rise to activate genes involved in DNA uptake.

Transformasome

A membrane complex that binds extracellular DNA and transports one strand into the cell while the other is degraded during natural transformation.

Transduction

The transfer of bacterial DNA from one cell to another mediated by bacteriophages.

Generalized Transduction

A phage-mediated transfer involving random fragments of bacterial host DNA.

Specialized Transduction

A phage-mediated transfer of specific bacterial genes resulting from incorrect excision of prophage DNA.

Prophage

Viral DNA integrated into the bacterial chromosome.

Transposons

Mobile genetic elements whose movement within or between DNA molecules increases genetic diversity.

RecA

A protein that facilitates homologous recombination by helping donor DNA pair and exchange strands with recipient DNA.

Single-Strand Recombination

A process where donor DNA replaces only one strand of recipient DNA, resulting after replication in one molecule with the original genotype and one recombinant molecule.

Double-Strand Recombination

A recombination process that incorporates a donor DNA segment into both strands of the recipient chromosome before replication.

Recombinant Molecule

A DNA molecule that combines recipient DNA with an incorporated donor DNA segment.