Biol-106 Exam #2: Microbial Growth and Control

Vocabulary-style flashcards covering microbial growth phases, oxygen requirements, identification methods, control techniques, antimicrobial drugs, and core concepts of epidemiology based on the lecture notes.

Binary fission

The process by which most bacteria reproduce, involving the splitting of one cell into two equal genetically identical daughter cells.

FtsZ protein

A protein that forms a ring at the middle of the cell during binary fission to facilitate division.

Lag phase

The phase of the exponential growth curve where the cell adapts to its environment and little division occurs.

Log (exponential) phase

The phase characterized by rapid cell division and growth.

Stationary phase

A growth phase where nutrients decline and the rate of growth equals the rate of death.

Death phase

The phase where cells die faster than they divide.

Direct cell count

A method using a microscope and counting chamber to count cells; it cannot distinguish between living and dead cells.

Coulter counter

An electronic device that counts cells by measuring changes in electrical resistance as they pass through a small opening.

Viable plate counting

A method that measures only living cells capable of reproducing; results are reported as colony-forming units (CFUs).

Turbidity

The cloudiness of a culture used to estimate cell numbers; increases as cell numbers increase.

Spectrophotometer

A device that measures light absorbance; higher absorbance (optical density) indicates a larger cell population.

Fragmentation

A form of asexual reproduction where a parent cell or organism breaks into pieces, and each fragment grows into a new individual.

Budding

A form of asexual reproduction involving the formation of a small outgrowth (bud) on the parent cell that enlarges and eventually detaches.

Biofilm

A structured community of microorganisms attached to a surface and embedded within a self-produced matrix called the extracellular polymeric substance (EPS).

Extracellular polymeric substance (EPS)

A matrix composed primarily of polysaccharides, proteins, nucleic acids ($DNA$), and water that holds microbial communities together in a biofilm.

Quorum sensing

A process of communication between bacteria within a biofilm that allows them to coordinate activities and share nutrients.

Obligate Aerobes

Microorganisms that require oxygen to survive for aerobic respiration; examples include $Mycobacterium\,tuberculosis$.

Obligate Anaerobes

Microbes that are harmed or killed by oxygen because they lack detoxifying enzymes; they live in environments like the gut.

Facultative anaerobes

Organisms that can grow with or without oxygen but grow better when oxygen is present; examples include $Escherichia\,coli$.

Aerotolerant Anaerobes

Microbes that do not use oxygen for metabolism but tolerate its presence due to detoxifying enzymes.

Microaerophiles

Microorganisms that require oxygen levels lower than those found in the atmosphere; examples include $Campylobacter\,jejuni$.

Superoxide Dismutase (SOD)

An enzyme that converts toxic superoxide radicals ($O_2^-$) into hydrogen peroxide ($H_2O_2$).

Catalase

An enzyme that breaks hydrogen peroxide ($H_2O_2$) into water and oxygen.

Gram Positive

Bacteria that stain purple and possess a thick peptidoglycan cell wall.

Gram Negative

Bacteria that stain pink and have a thin peptidoglycan layer and an outer membrane.

Psychrophiles

Microorganisms adapted to cold temperatures.

Mesophiles

Microbes that thrive at moderate temperatures ($20^\circ\text{C}$ to $45^\circ\text{C}$), including human pathogens.

Halophiles

Microorganisms that require high salt concentrations for growth.

Barophiles

Also called piezophiles, these organisms are adapted to extremely high-pressure environments like the deep ocean.

BSL-4

The highest biosafety level for dangerous and exotic pathogens like Ebola virus that require the most stringent containment.

Sterilization

A process that destroys all microorganisms, including endospores.

Autoclaving

A method of sterilization using steam under pressure at $121^\circ\text{C}$ for $15\,minutes$.

Antisepsis

The use of chemicals on living tissue to inhibit or destroy microbes.

Quaternary ammonium compounds (Quats)

Chemical agents that disrupt cell membranes, causing leakage of cellular contents and cell death.

Compound 606 (Salvarsan)

The first successful chemotherapeutic agent, developed by Paul Ehrlich in $1909$ to treat syphilis.

Prontosil

The first commercially successful sulfa drug; its active component is sulfanilamide.

Bacteriostatic

Drugs that inhibit the growth and reproduction of bacteria without directly killing them.

Bactericidal

Drugs that directly kill bacteria, preferred for severe infections or patients with weakened immune systems.

Beta-lactam ring

A four-membered cyclic amide ring that acts as the core structure for penicillins and cephalosporins, targeting penicillin-binding proteins (PBPs).

Artemisinin

An antiprotozoal drug used for malaria that contains an endoperoxide bridge and generates free radicals to damage parasite proteins.

Ivermectin

An antihelminthic drug that opens glutamate-gated chloride channels, causing paralysis in worms.

Acyclovir

A nucleoside analog activated by viral thymidine kinase that inhibits viral $DNA$ polymerase in HSV and VZV.

Morbidity

The state of illness or disease within a population.

Incidence

The number of new cases of a disease that develop during a specific time period.

Prevalence

The total number of existing cases (old and new) present in a population at a given time.

Sporadic disease

A disease that occurs occasionally and irregularly with no predictable pattern, such as Tetanus.

Endemic disease

A disease consistently present at a baseline level within a particular geographic region.

Epidemic

A significant rise in the number of disease cases above expected levels within a specific area.

John Snow

Known as the father of epidemiology; investigated the $1854$ London cholera outbreak linked to the Broad Street pump.

Joseph Lister

Pioneer of antiseptic surgery who introduced disinfectants like carbolic acid to reduce surgical infections.