Microbial Metabolism, Biochemistry, and Genetics Lecture Review

Comprehensive flashcards covering microbial metabolism (enzymes, respiration, fermentation), basic biological chemistry (bonding, macromolecules), cell anatomy (organelles, transport), and microbial genetics (DNA replication, transcription, and translation).

Metabolism

The sum of the chemical reactions in an organism.

Catabolism

Chemical reactions that provide energy and building blocks for anabolism by breaking down large molecules.

Anabolism

Chemical reactions that use energy and building blocks to build large molecules; also known as synthesis reactions.

Activation Energy

The amount of energy needed to disrupt electronic configurations and start a chemical reaction.

Enzymes

Proteins that serve as biological catalysts to speed up reactions by lowering the activation energy.

Apoenzyme

The protein portion of an enzyme.

Cofactor

The nonprotein component of an enzyme.

Holoenzyme

An active enzyme consisting of an apoenzyme plus its cofactor.

Turnover Number

The number of substrate molecules an enzyme converts to a product per second, generally between $1$ and $10,000$.

Competitive Inhibitors

Molecules that fill the active site of an enzyme and compete with the substrate.

Noncompetitive Inhibition

A type of inhibition where the inhibitor binds to an allosteric site rather than the active site, altering the enzyme's shape.

Feedback Inhibition

A control mechanism where the end-product of a metabolic pathway inhibits an enzyme's activity earlier in the pathway.

Oxidation

The removal of electrons from a molecule.

Reduction

The gain of electrons by a molecule.

Substrate-Level Phosphorylation

The generation of $ATP$ by the direct transfer of a high-energy phosphate group from a phosphorylated compound to $ADP$.

Oxidative Phosphorylation

The process where energy released from the transfer of electrons in an electron transport chain is used to generate $ATP$.

Glycolysis

The oxidation of glucose to pyruvic acid, producing a net gain of $2$ $ATP$ and $2$ $NADH$ per glucose molecule.

Krebs Cycle

A series of chemical reactions that breaks down derivatives of pyruvic acid to harvest electrons, resulting in $2$ $ATP$, $6$ $NADH$, and $2$ $FADH_2$ per glucose.

Electron Transport Chain (ETC)

A sequence of carrier molecules, located in the mitochondrial inner membrane of eukaryotes or plasma membrane of prokaryotes, that release energy via redox reactions.

$ATP$ Synthase

An enzyme/protein channel that allows protons ($H^+$) to cross the membrane, catalyzing the reaction of $ADP \rightarrow ATP$.

Aerobic Respiration

Respiration where the final electron acceptor in the electron transport chain is molecular oxygen ($O_2$).

Anaerobic Respiration

Respiration where the final electron acceptor is an inorganic substance other than oxygen, such as $NO_3^-$, $SO_4^{2-}$, or $CO_3^{2-}$.

Fermentation

A process that releases energy from the oxidation of organic molecules, does not require oxygen, and uses an organic molecule as the final electron acceptor.

Photoautotroph

An organism that uses light as its energy source and $CO_2$ as its carbon source.

Chemoheterotroph

An organism that uses chemical compounds for energy and organic compounds as its carbon source.

Amphibolic Pathways

Metabolic pathways that function in both catabolic and anabolic capacities.

Ionic Bond

An attraction between ions of opposite charge formed when one atom loses electrons and another gains them.

Covalent Bond

A chemical bond formed when two atoms share one or more pairs of electrons.

Hydrogen Bond

A relatively weak bond formed between a hydrogen atom covalently bonded to one oxygen or nitrogen atom and another oxygen or nitrogen atom.

$$pH$$

The expression of the amount of $H^+$ in a solution, calculated as $-log[H^+]$.

Fluid Mosaic Model

A description of the plasma membrane as a dynamic, viscous structure where phospholipids and proteins move laterally.

Osmosis

The diffusion of water through a semipermeable membrane down its concentration gradient.

Ribosomes

The sites of protein synthesis in a cell, composed of $rRNA$ and protein; eukaryotic ribosomes are $80S$.

Mitochondria

Organelles responsible for aerobic respiration and $ATP$ production, containing their own $DNA$ and a dual membrane.

Genotype

The genetic makeup of an organism; the specific genes it possesses.

Phenotype

The physical expression of an organism's genes.

Semiconservative Replication

The process of $DNA$ replication in which each new double-stranded $DNA$ molecule consists of one original parental strand and one newly synthesized daughter strand.

$DNA$ Polymerase

The enzyme that synthesizes $DNA$ by adding nucleotides to the $3'$ end of a growing strand and provides proofreading capabilities.

Transcription

The process of copying the genetic information from a $DNA$ sense strand into a complementary strand of $mRNA$ using $RNA$ polymerase.

Translation

The process where the sequence of codons in $mRNA$ is used to specify the amino acid sequence of a protein.

Codon

A sequence of three nucleotides on $mRNA$ that codes for a specific amino acid or a signal to stop protein synthesis.