Microbial Metabolism & Molecular Genetics

These flashcards cover key concepts in microbial metabolism, molecular genetics, gene regulation, mutations, and related topics from the lecture.

Exergonic Reactions

Reactions that release energy and have a negative Gibbs Free Energy (\Delta G^{\circ'}).

Endergonic Reactions

Reactions that absorb energy and have a positive Gibbs Free Energy (\Delta G^{\circ'}).

OIL RIG

An acronym for 'Oxidation Is Loss, Reduction Is Gain' used in redox reactions.

Reduction Potential ($$E_0'$')

A measure of the tendency of a species to gain electrons; more negative E_0' indicates better electron donors.

Substrate-Level Phosphorylation (SLP)

The direct transfer of a phosphate group to ADP from a high-energy organic molecule.

Oxidative Phosphorylation (OP)

ATP production driven by the proton motive force generated by the electron transport chain.

Chemolithoheterotroph

An organism that uses chemicals for energy, inorganic electrons, and organic carbon.

Nitrification

The process by which ammonia (NH3) is oxidized to nitrate ($$NO3^-$).

Transcription

The process of synthesizing RNA from a DNA template.

Polycistronic mRNA

mRNA that codes for multiple proteins, a common feature in bacterial genes.

Riboswitches

RNA domains that bind small molecules to control gene expression.

Point Mutation

A mutation affecting only a single nucleotide in a DNA sequence.

Frameshift Mutation

A mutation caused by insertion or deletion of nucleotides that shifts the reading frame.

Auxotroph

A mutant organism that requires additional nutrients for growth compared to the wild type.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated from free-living bacteria.

Quorum Sensing

The ability of bacteria to sense and respond to the density of their population.

Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antibiotic that inhibits growth of a bacterium.

Bacteriostatic

A class of antibiotics that inhibit bacterial growth without killing the bacteria.

Electron Transport Chain (ETC)

A series of protein complexes that transfer electrons, creating a proton gradient for ATP synthesis.

Translation

The process of synthesizing proteins from an mRNA template.

Operon

A unit of genomic material containing a cluster of genes controlled by a single promoter.

Bactericidal

A class of antibiotics that kill bacteria.

Biofilm

A complex community of microbes attached to a surface and embedded in an extracellular matrix.

Horizontal Gene Transfer (HGT)

The transfer of genetic material between independent organisms, not via parent-offspring inheritance.

Adenosine Triphosphate (ATP)

The main energy currency of the cell, carrying energy in its phosphate bonds.

Enzymes

Biological catalysts that speed up the rate of biochemical reactions without being consumed.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid or signals termination during protein synthesis.

Plasmid

A small, circular, extrachromosomal DNA molecule found in bacteria that can replicate independently of the main chromosome.

Transformation

A type of Horizontal Gene Transfer where bacteria take up naked DNA from their environment.

Activation Energy

The minimum amount of energy required to initiate a chemical reaction.

Active Site

The specific region on an enzyme where a substrate binds and catalysis occurs.

Competitive Inhibition

An enzyme inhibition where the inhibitor binds to the active site, competing with the substrate.

Non-competitive Inhibition

An enzyme inhibition where the inhibitor binds to an allosteric site (different from the active site), altering the enzyme's shape and reducing its activity.

Allosteric Regulation

Regulation of an enzyme's activity by the binding of an effector molecule at a site other than the active site.

Feedback Inhibition

A regulatory mechanism where the end-product of a metabolic pathway inhibits an enzyme earlier in the pathway.

Redox Reaction

A chemical reaction involving the transfer of electrons between reactants, where oxidation and reduction occur simultaneously.

Electron Donor

A molecule that loses or gives up electrons in a redox reaction.

Electron Acceptor

A molecule that gains or accepts electrons in a redox reaction.

Aerobic Respiration

Cellular respiration that uses oxygen as the final electron acceptor in the electron transport chain to produce ATP.

Anaerobic Respiration

Cellular respiration that uses an inorganic molecule other than oxygen (e.g., nitrate, sulfate) as the final electron acceptor.

Fermentation

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen, regenerating NAD+.

Glycolysis

The metabolic pathway that breaks down glucose into two molecules of pyruvate, producing a small amount of ATP and NADH.

Krebs Cycle (Citric Acid Cycle)

A central metabolic pathway in aerobic organisms that oxidizes acetyl-CoA to CO2, producing ATP, NADH, and FADH2 .

Proton Motive Force (PMF)

The electrochemical gradient of protons across a membrane, generated by proton pumps during electron transport, used for ATP synthesis.

DNA Replication

The biological process of producing two identical copies of DNA from an original DNA molecule.

DNA Polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides complementary to a template strand during replication.

RNA Polymerase

An enzyme that synthesizes RNA from a DNA template during transcription.

Central Dogma of Molecular Biology

The fundamental concept that genetic information flows from DNA to RNA to protein.

Promoter

A specific DNA sequence upstream of a gene that acts as a binding site for RNA polymerase to initiate transcription.

Terminator

A DNA sequence that signals the end of transcription and causes RNA polymerase to detach from the DNA template.

Messenger RNA (mRNA)

An RNA molecule that carries genetic information from DNA in the nucleus to ribosomes in the cytoplasm, where proteins are synthesized.

Transfer RNA (tRNA)

An RNA molecule that carries a specific amino acid to the ribosome during translation, matching it to the corresponding mRNA codon.

Ribosomal RNA (rRNA)

A structural and catalytic component of ribosomes, essential for protein synthesis.

Genetic Code

The set of rules by which information encoded in DNA or mRNA is translated into proteins by living cells.

Anticodon

A sequence of three nucleotides on a tRNA molecule that is complementary to a codon on an mRNA molecule, ensuring the correct amino acid is added.

Conjugation

A type of Horizontal Gene Transfer in bacteria involving direct cell-to-cell contact and the transfer of genetic material (usually a plasmid) through a pilus.

Transduction

A type of Horizontal Gene Transfer where bacterial DNA is transferred from one bacterium to another via a bacteriophage (virus).

Transposons

Segments of DNA that can move from one position to another within a genome, often called 'jumping genes'.

CRISPR-Cas System

A prokaryotic immune system that defends against foreign genetic elements, now widely used as a gene editing tool.