General Microbiology Exam 2 Flashcards

Comprehensive vocabulary flashcards covering bacterial morphology, structures, genetics, growth requirements, and metabolic pathways for BIO 220 Exam 2.

Coccus

A bacterial shape that is spherical, oval, bean-shaped, or pointed.

Bacillus

A rod-shaped bacterium that may appear spindle, club, drumstick, or filamentous.

Vibrio

A curved, comma-shaped rod bacterium; an example is $Vibrio\,cholera$.

Spirillum

A bacterium with a rigid spiral shape.

Spirochete

A bacterium with a flexible spiral shape; examples include $Borrelia\,burgdorferi$ and $Treponema\,pallidum$.

Pleomorphism

Variation in size and shape within a single bacterial species; observed in $Rickettsia\,rickettsii$, $Corynebacterium$, and $Rhizobium$.

Staphylococci

An arrangement of cocci in grape-like clusters.

Streptococci

An arrangement of cocci in chains.

Sarcina

A cubical packet arrangement of cocci.

Palisades

An arrangement of bacilli in side-by-side rows.

Flagellum Parts

The three components of a flagellum: filament, hook, and basal body.

Peritrichous

A flagellar arrangement where flagella are dispersed all over the cell surface.

Axial Filaments

Also called periplasmic flagella; found only in spirochetes and located between the cell wall and cytoplasmic membrane for twisting movement.

Fimbriae

Short, bristle-like fibers used for attachment and biofilm formation; common in Gram-negative bacteria like $Neisseria\,gonorrhoeae$.

Pili (Sex Pili)

Structures found only in Gram-negative bacteria used for DNA transfer during conjugation.

Glycocalyx

A coating of repeating polysaccharides that provides protection, prevents water loss, and increases virulence.

Capsule

A thick, firmly attached glycocalyx that protects bacteria from phagocytosis and increases pathogenicity.

Peptidoglycan

A cell wall component made of $N$-acetylglucosamine ($NAG$) and $N$-acetylmuramic acid ($NAM$) cross-linked by short peptide chains.

Gram-Positive Cell Wall

Characterized by thick peptidoglycan ($20-80\,nm$) and teichoic acids; lacks an outer membrane.

Gram-Negative Cell Wall

Characterized by thin peptidoglycan ($1-3\,nm$) and an outer membrane containing lipopolysaccharide ($LPS$), lipoproteins, and porins.

Lipopolysaccharide (LPS)

An endotoxin found in the outer membrane of Gram-negative bacteria that can cause fever and shock.

Mycoplasma

Bacteria that naturally lack a cell wall, contain sterols in their membrane, and cause primary atypical pneumonia.

Plasmids

Small, circular DNA molecules that replicate independently of the chromosome and carry traits like antibiotic resistance.

Conjugation

A method of horizontal gene transfer where DNA is transferred from one bacterium to another through a pilus.

Transformation

The uptake of free DNA from the surrounding environment by a bacterial cell.

Transduction

Horizontal gene transfer between bacteria of the same species mediated by a bacteriophage.

Endospore

A resistant structure produced for survival during harsh conditions by genera such as $Bacillus$ and $Clostridium$.

Macronutrients

Essential elements needed in large amounts for cell structure and metabolism, such as Carbon, Hydrogen, and Oxygen.

Photoautotroph

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

Chemoheterotroph

An organism that obtains both carbon and energy from organic compounds; includes most bacteria, fungi, and pathogens.

Saprobes

Decomposers that feed on dead organic matter by releasing enzymes outside the cell.

Hypertonic environment

A condition where solute concentration is higher outside the cell, causing water to leave and limiting microbial growth.

Psychrotroph

Organisms that grow slowly in the cold (optimum $15-30\,^{\circ}C$) and cause food spoilage, such as $Listeria\,monocytogenes$.

Mesophile

Microbes with an optimum growth temperature of $20-40\,^{\circ}C$; includes most human pathogens.

Facultative Anaerobe

An organism that grows with or without oxygen, using aerobic respiration when available and fermentation when absent.

Quorum Sensing

The process by which microbes in a biofilm communicate to monitor population size.

Generation Time

The time required for one bacterial cell to divide; calculated as $\text{Number of cells} \times 2^n$.

Log (Exponential) Phase

The growth curve phase characterized by maximum cell division and highest sensitivity to antibiotics.

Anabolism

The aspect of metabolism that builds complex molecules and requires energy in the form of $ATP$.

Catalyst

A substance, such as an enzyme, that speeds up a chemical reaction without being consumed or becoming part of the product.

Activation Energy

The energy needed to start a chemical reaction, which enzymes lower to increase reaction speed.

Denaturation

The inactivation of an enzyme due to changes in shape caused by high temperature or extreme pH.

Competitive Inhibition

A process where a molecule resembling the substrate competes for the active site, such as sulfonamide drugs mimicking $PABA$.

Noncompetitive Inhibition

A process where a molecule binds to an allosteric (regulatory) site, changing the enzyme shape so the substrate no longer fits.

Catalase Test

A biochemical test used to differentiate $Staphylococcus$ (positive/bubbles) from $Streptococcus$ (negative/no bubbles).

Aerobic Respiration

A metabolic pathway using glycolysis, Krebs cycle, and ETS with oxygen as the final electron acceptor, yielding $38\,ATP$ in bacteria.

Anaerobic Respiration

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

Fermentation

A pathway that uses only glycolysis and an organic molecule as the final electron acceptor, yielding $2\,ATP$.

Glycolysis

The first stage of aerobic respiration, anaerobic respiration, and fermentation, which converts glucose to pyruvic acid.

Electron Transport System (ETS)

The respiratory chain that transfers electrons through carrier proteins to create the most $ATP$ ($34$ in bacteria).