J210 Lecture 4

Flashcards covering key vocabulary related to microbial metabolism and growth from the lecture notes.

Metabolism

The sum of all biochemical reactions, including anabolic (synthesis) and catabolic (degradation) processes.

Catabolism

The degradation of organic molecules to provide energy (ATP source) and building blocks.

Anabolism

The synthesis of larger organic molecules from smaller ones, requiring energy.

Heterotroph

Organisms that use preformed organics (sugars, protein, fat) as their carbon source and energy.

Fastidious

Microbes that require extra nutritional supplements (more than those in ordinary BHI medium) to grow.

Autotroph

Organisms that use CO2 as a carbon source and a non-organic source for energy, such as photosynthesis.

Cellular Respiration

The process in which nutrients are converted into usable energy, with glucose being the most efficient energy-producing molecule.

Glycolysis

A central metabolic pathway that converts glucose to pyruvate, yielding 2 pyruvate and 2 ATP.

Krebs Cycle (TCA cycle)

A central metabolic pathway that uses carbon in pyruvate to produce ATP, CO2, and electrons (e-).

Electron Transport Chain

A metabolic process where electrons feed into a chain, pumping out protons to create a gradient, which is then used to generate up to 34 ATP.

Chemiosmotic gradient

Potential energy created by protons pumped out by the electron transport system.

ATP synthase

An enzyme that uses the energy from the chemiosmotic gradient to synthesize ATP from ADP and inorganic phosphate.

Fermentation

An alternative catabolic pathway for ATP synthesis that occurs under anaerobic conditions, without oxygen.

Lactic acid fermentation

A process where some organisms ferment pyruvate into lactic acid, occurring in some bacteria and animal muscle cells.

Anaerobic Respiration

A process where some organisms use an alternative to O2 as the final electron acceptor during ATP synthesis.

Anaerobes

Organisms that use an alternative to O2 as the final electron acceptor during ATP synthesis.

Enzymes

Molecules, nearly always proteins, that catalyze all chemical steps occurring in life by converting substrates into products.

Substrates

The molecules at the beginning of a chemical reaction, which an enzyme converts into products.

Products

The different molecules created by an enzyme from its substrates during a chemical reaction.

DNA (Deoxyribonucleic acid)

The most important molecule in the cell, comprised of 4 bases (A, C, G, T) linked to a deoxyribose-phosphate backbone, forming a double helix.

Base pairing

The specific pairing of bases in DNA: Adenine (A) with Thymine (T), and Cytosine (C) with Guanine (G).

Replication fork

The position where the DNA double helix is unzipped by the helicase enzyme during DNA replication.

Helicase

An enzyme that breaks hydrogen bonds between complementary base pairs, unzipping the double helix at the replication fork.

DNA polymerase

An enzyme that joins together nucleotides with phosphodiester bonds to form a new complementary polynucleotide strand during DNA replication.

Phosphodiester bonds

Strong covalent bonds formed by DNA polymerase to link nucleotides together in a new DNA strand.

Daughter chromosomes

The two copies of the DNA molecule that form behind the replication fork after DNA replication.

PCR (Polymerase Chain Reaction)

A common technique used to make a huge number of copies of a gene in vitro, essential for sequencing, diagnosing diseases, and genetic fingerprinting.

RNA (ribonucleic acid)

A molecule encoded by DNA that uses ribose sugar instead of deoxyribose and has 4 bases (A, U, G, C, with Uracil instead of Thymine).

mRNA (messenger RNA)

A type of RNA that carries genetic information from DNA to the ribosome for protein synthesis.

rRNA (ribosomal RNA)

A type of RNA that forms part of the ribosome, the cellular machinery for protein synthesis.

tRNA (transfer RNA)

A type of RNA that carries specific amino acids to the ribosome during protein synthesis.

Coupled transcription and translation

In prokaryotes, the simultaneous occurrence of RNA transcription and protein translation in the cytoplasm.

Binary Fission

The process of bacterial cell division, where one cell divides into two daughter cells.

Generation time (doubling time)

The time it takes for a bacterial population to undergo one cycle of binary fission and double in number.

LAG PHASE

The initial phase of bacterial growth where growth is slow as bacteria acclimate to their new habitat and nutrients.

LOG PHASE

The phase of bacterial growth where bacteria multiply exponentially, doubling in number every few minutes.

STATIONARY PHASE

The phase of bacterial growth where booming growth stops, and the number of bacteria stabilizes due to competition for dwindling food and nutrients.

DEATH PHASE

The final phase of bacterial growth where toxic waste products build up, food is depleted, and bacteria begin to die.

Exponential growth

Growth by geometric progression (1→2→4→8…), where a bacterial population doubles at regular intervals under favorable conditions.

Obligate aerobic bacteria

Bacteria that require molecular oxygen for growth and gather at the top of a liquid culture.

Obligate anaerobic bacteria

Bacteria that are killed by oxygen and gather at the bottom of a liquid culture to avoid it.

Facultative anaerobic bacteria

Bacteria that can grow with or without oxygen, but preferentially grow with oxygen, spreading throughout a liquid culture but denser at the top.

Microaerophiles

Bacteria that require oxygen but only at low concentrations and gather at the upper part of a test tube, but not at the very top.

Aerotolerant anaerobes

Bacteria that do not utilize oxygen but are not affected by it, spreading evenly throughout a liquid culture.

Reactive oxygen species (ROS) / Free radicals

Highly reactive and aggressive intermediate products of oxygen metabolism that can cause damage to cellular components due to an extra electron.

Superoxide dismutase (SOD)

An enzyme that reacts with harmful free radicals (superoxide) to form hydrogen peroxide (H2O2), which is still harmful but less so.

Catalase

An enzyme that converts hydrogen peroxide (H2O2) into oxygen (O2) and water (H2O), helping to neutralize ROS.

Glutathione Peroxidase

An enzyme that converts hydrogen peroxide (H2O2) into oxygen (O2) and water (H2O), helping to neutralize ROS.

Psychrophile

Bacteria that thrive in cold temperatures, typically between -15°C and 5°C.

Mesophile

Bacteria that thrive at moderate temperatures, such as human body temperature (around 37°C).

Thermophile

Bacteria that thrive in hot temperatures, typically around 60°C.

Extreme thermophile

Bacteria that thrive in very hot temperatures, typically above 100°C.

Acidophile

Bacteria that grow best in low pH (high acid) environments, typically below 5.

Neutrophile

Bacteria that grow best in neutral pH environments, typically between 6 and 8.

Alkalophile

Bacteria that grow best in high pH environments, typically above 8.

Nosocomial infections

Hospital-acquired infections that appear 48 hours or more after hospital admission or within 30 days after discharge, secondary to the patient's original condition.

Commensal bacteria

Bacteria that live in harmony with a host, providing benefits such as immune system activation, mucosal barrier development, vitamin synthesis, and pH reduction.

Koch's postulates

A set of four criteria used to experimentally prove that a specific microbe causes a specific disease.

Pure culture

A population of cells derived from a single cell, where all cells are genetically identical.

Mixed culture

A community where different types of organisms, often bacteria, live together, which is common in nature.

Cloning (in biology)

The process of producing populations of genetically identical individuals.