Bacterial and Archaeal Growth - Chapter 07 Flashcards

A comprehensive set of vocabulary flashcards covering bacterial and archaeal reproductive strategies, cell cycles, growth phases, environmental adaptations, and laboratory cultivation methods based on the lecture transcript.

Binary Fission

The most common reproductive strategy in bacteria and archaea where a cell replicates its genome, increases in size, and divides into two equal daughter cells.

Budding

A vegetative outgrowth of yeast and some bacteria as a means of asexual reproduction where the daughter cell is smaller than the parent.

Baeocytes

Small, spherical, reproductive cells produced by some cyanobacteria through multiple fission.

Cell Cycle

The complete sequence of events extending from the formation of a new cell through the next cell division, involving growth, chromosome replication, and cytokinesis.

Replisome

The DNA synthesis machinery that assembles at the origin of replication to carry out DNA replication.

DnaA

A protein that initiates DNA replication in E. coli by accumulating as the cell mass increases.

Septation

The formation of a cross wall (septum) between two daughter cells during cytokinesis.

Divisome

A transmembrane protein machine targeted to the division site that regulates the assembly of the septum and peptidoglycan remodeling.

FtsZ

A prokaryotic homologue of the eukaryotic protein tubulin that plays a key role in bacterial cell division by forming a Z-ring at the central septum.

MreB

A protein that serves as a scaffold for the elongasome in rod-shaped cells, creating filaments along the cytoplasmic face of the plasma membrane.

Crescentin

A protein that localizes to one side of the cell in certain microbes, resulting in an asymmetric cell wall and a vibroid (curved) shape.

CdvA

An archaeal cell division protein in Sulfolobus spp. that binds the membrane and forms a non-contractile ring at midcell.

CdvB

An archaeal cell division protein that forms a ring which constricts to separate daughter cells.

Batch Culture

Microorganisms cultivated in a liquid medium within a closed vessel.

Lag Phase

The initial phase of the growth curve where cells are synthesizing new components, replenishing materials like ribosomes and $ATP$, and adapting to new conditions.

Exponential Phase

The phase of growth where the rate of division is constant and maximal, and the population is most uniform in chemical and physical properties.

Stationary Phase

The phase in a closed system where growth ceases and the total number of viable cells remains constant due to nutrient limitation or waste accumulation.

Generation (doubling) time ($g$)

The time required for a microbial population to double in size.

Growth rate constant ($k$)

The number of generations per unit time, calculated as $k = \frac{n}{t}$.

Extremophiles

Organisms that grow under harsh environmental conditions, such as extreme temperature or pressure, that would kill most other organisms.

Halophiles

Microbes that require $NaCl$ or other salts at a concentration above approximately $0.2\,M$ for growth.

Water activity ($a_w$)

A measure of the degree of water availability, equal to $1/100$ the relative humidity of a solution or the ratio of a solution’s vapor pressure to that of pure water.

Acidophiles

Microorganisms that grow best in environments with a pH between $0$ and $5.5$.

Cardinal Temperatures

The minimum, maximum, and optimal temperatures for growth of a specific microorganism.

Psychrophiles

Microbes adapted to cold temperatures, with a growth range of $0^{\circ}C$ to $20^{\circ}C$.

Hyperthermophiles

Microbes that grow at very high temperatures, typically between $85^{\circ}C$ and $100^{\circ}C$.

Obligate Aerobe

An organism that requires the presence of oxygen ($O_2$) to grow.

Facultative Anaerobes

Organisms that do not require $O_2$ for growth but grow significantly better in its presence.

Superoxide Dismutase (SOD)

An enzyme that catalyzes the destruction of superoxide radicals, protecting cells from oxidative stress.

Piezophilic (barophilic)

Organisms that require high hydrostatic pressure for growth.

Quorum Sensing

A process where bacterial cells communicate via small molecules, such as $N$-acylhomoserine lactone (AHL), to regulate gene expression based on population density.

Biofilm

A complex, slime-enclosed community of microbes attached to a surface.

Defined (synthetic) Medium

A culture medium where each ingredient can be defined with a specific chemical formula.

Selective Media

Media designed to allow the growth of particular microorganisms while inhibiting the growth of others.

Differential Media

Media that distinguish among different groups of microbes based on biological characteristics, such as lactose fermentation on MacConkey agar.

Colony Forming Units (CFU)

A unit used to estimate the number of viable microorganisms in a sample based on the number of colonies that grow on a plate.

Chemostat

A continuous culture system that maintains cells in exponential growth by providing a constant supply of nutrients and removing waste.