Cell Cycle, Growth, and Microbial Physiology

A set of fill-in-the-blank flashcards covering bacterial replication, cell division, peptidoglycan synthesis, growth phases, culture methods, stress responses, biofilms, and quorum sensing.

The predominant mode of replication for bacteria and archaea is __.

Binary fission

In microbiology, “growth” refers to an increase in __ rather than cell size.

cell number

In __ reproduction, the parent cell forms small daughter “buds.”

budding

During __ fission, an apical cell undergoes many divisions to release baeocytes.

multiple

Unlike eukaryotes, the bacterial cell cycle consists of only __ major phases.

three

Phase 1 of the bacterial cell cycle is a growth period analogous to __ in eukaryotes.

G1

Phase 2 of the bacterial cell cycle combines functions similar to the __ phases in eukaryotes.

S and M

Bacteria lack the __ growth phase found between S and M in eukaryotes.

G2

Phase 3 of the bacterial cell cycle ends with formation of a dividing wall called the __.

septum

The cytoskeletal protein that assembles into a contractile Z-ring is __.

FtsZ

The collection of proteins that build the septum with FtsZ is called the __.

divisome

At the cell poles, __ prevents FtsZ polymerization and Z-ring formation.

MinC (and MinD)

The protein __ acts like a broom, sweeping MinD away from mid-cell.

MinE

Peptidoglycan subunits NAM and NAG are first attached to the nucleotide carrier __.

UDP

The lipid carrier that transports peptidoglycan precursors across the membrane is __.

bactoprenol

The flipped NAM-NAG-bactoprenol complex is commonly called __.

Lipid II

Enzymes called __ break existing bonds so new peptidoglycan can be inserted.

autolysins

In coccoid bacteria, new peptidoglycan is inserted only at the __, yielding a sphere.

mid-cell ring

Sidewall elongation in rod-shaped cells is guided by the actin-like protein __.

MreB

The protein __ localizes to one side of vibrioid cells to create curvature.

crescentin

Laboratory media are usually described as __ because they are nutrient rich.

eutrophic

A typical growth curve for a closed culture is plotted as log cell number versus __.

time

During the __ phase, cells synthesize new components to adapt to fresh medium.

lag

The phase of constant, maximal growth rate is the __ phase.

exponential (log)

Even with extra nutrients, transporter saturation can __ further growth increases.

limit

When growth equals death, cultures enter the __ phase.

stationary

Nutrient limitation, oxygen lack, or waste buildup are common causes of the __ phase.

stationary

Cells that are alive but non-recoverable on plates are termed __ during death phase.

VBNC (Viable But Not Culturable)

Some bacteria undergo __ cell death, a genetically programmed suicide.

programmed

Successive waves of variants arise during the prolonged __ phase (LTSP).

long-term stationary

The time required for a microbial population to double is called the __ time.

generation (doubling)

A medium whose exact chemical composition is known is called __ or synthetic.

defined

A medium that distinguishes among microbes based on appearance is __.

differential

Media formulated so that only certain microbes grow are described as __.

selective

Growth conditions that specifically favor microbes with a desired trait are called __ cultures.

enrichment

A __ culture contains cells that all descended from a single parent cell.

pure

Optical density measurements below 10⁷ cells /ml are unreliable because turbidity methods are __.

insensitive

Very low cell densities are best quantified by viable count using __ filtration.

membrane

A continuously fed, constant-volume culture device is called a __.

chemostat

At steady state in a chemostat, the microbial growth rate equals the __ rate.

dilution

Dilution rate is mathematically defined as __ (give formula).

F / V (flow rate divided by culture volume)

Most natural habitats are __, meaning they are low in nutrients.

oligotrophic

Global transcriptional changes to stress in bacteria are often coordinated by __ factors.

sigma

__ cells are non-growing survivors that tolerate antibiotics without resistance genes.

Persister

The slime-encased, surface-attached community of microbes is known as a __.

biofilm

Microbes detect population density via chemical signaling called __ sensing.

quorum

In Vibrio fischeri, the autoinducer __ activates the lux operon for bioluminescence.

AHL (N-acyl-homoserine lactone)

The light produced by V. fischeri enables a symbiosis with the __ squid.

Hawaiian bobtail

Quorum sensing can regulate community behaviors such as virulence, DNA uptake, biofilm formation, and __ production.

light (bioluminescence)