Bacterial Classification and Biology

Flashcards covering bacterial classification, structures, metabolism, reproduction, and their relationship with human health based on Chapter 6 lecture notes.

Prokaryotic

A characteristic of all bacteria describing their simple cellular structure lacking a true nucleus or membrane-bound organelles.

Eubacteria

The group of bacteria generally referred to as germs, characterized by the presence of peptidoglycan in their cell walls.

Archaebacteria

More ancient than eubacteria, these bacteria live in harsh environments, have unusual lipids in their cell membranes, and lack peptidoglycan in their cell walls.

Peptidoglycan

A protein-sugar compound found in the cell walls of eubacteria.

Methanogens

A group of Archaebacteria that harvest energy by converting $H_2$ and $CO_2$ into methane gas; they live only in anaerobic conditions.

Extreme halophiles

Salt-loving Archaebacteria that live in high salt concentrations, such as the Great Salt Lake, and use salt to generate ATP.

Thermoacidophiles

Archaebacteria that live in extremely acidic environments ($\text{pH} < 2$) with high temperatures up to $110\text{ }^\text{o}\text{C}$, such as volcanic vents.

Bacilli

Rod-shaped eubacteria.

Cocci

Sphere-shaped eubacteria.

Spirilla

Spiral-shaped eubacteria.

Streptococci

Sphere-shaped bacteria (cocci) that occur in chains.

Staphylococci

Sphere-shaped bacteria (cocci) that occur in clusters.

Gram stain

A staining procedure used to classify eubacteria into two groups based on their cell wall structure: gram positive and gram negative.

Gram positive bacteria

Bacteria that retain the crystal violet stain and appear purple under a microscope due to a thicker layer of peptidoglycan.

Gram negative bacteria

Bacteria that appear pink under a microscope because they have a thinner layer of peptidoglycan and do not retain the purple stain.

Cyanobacteria

A phylum of photosynthetic eubacteria that produce carbohydrates and give off oxygen as a waste product.

Heterocyst

Specialized cells in certain cyanobacteria that contain enzymes for fixing atmospheric nitrogen.

Eutrophication

A sudden increase in the population of cyanobacteria due to high availability of nutrients like phosphate and nitrate, also known as a population bloom.

Spirochetes

Spiral-shaped eubacteria that move with a corkscrew-like rotation, including the species Treponema pallidum which causes syphilis.

Antibiotics

Chemicals produced by microorganisms or synthesized in labs that inhibit the growth of or kill other microorganisms.

Proteobacteria

One of the largest and most diverse phyla of bacteria, including enteric bacteria, chemoautotrophs, and nitrogen-fixing bacteria.

Rhizobium

A genus of nitrogen-fixing bacteria that lives symbiotically with plants to convert atmospheric $N_2$ into a form plants can use.

Plasmid

A self-replicating loop of DNA in the cytoplasm that can contain genes obtained through genetic recombination.

Capsule

An outer covering made of polysaccharides that protects the cell against drying, harsh chemicals, and host white blood cells.

Pili

Short hair-like protein structures that help bacteria adhere to host cells and transfer genetic material.

Endospore

A dormant structure produced by some gram-positive bacteria to survive harsh environmental extremes like heat, drought, and radiation.

Flagellum

A protein structure used by many bacteria for movement, often propelling the cell in a turn-and-tumble motion.

Saprophytes

Heterotrophic bacteria that live on dead or decaying matter.

Obligate anaerobic

Bacteria that cannot live in the presence of $O_2$.

Psychrophile

Bacteria that grow best in cold temperatures between $0\text{ }^\text{o}\text{C}$ and $20\text{ }^\text{o}\text{C}$.

Mesophile

Bacteria that grow best in temperatures between $20\text{ }^\text{o}\text{C}$ and $40\text{ }^\text{o}\text{C}$.

Thermophile

Bacteria that grow best in high temperatures from $40\text{ }^\text{o}\text{C}$ to $110\text{ }^\text{o}\text{C}$.

Transformation

A type of genetic recombination where a bacterial cell takes in DNA from a nearby dead cell.

Conjugation

The process where two living bacteria bind together and one transfers genetic information to the other via a conjugation bridge.

Transduction

A process of genetic recombination where a virus carries a fragment of DNA from a host bacterium to a new bacterial cell.

Pathology

The scientific study of diseases.

Pathogens

Bacteria or other agents that cause disease.

Exotoxins

Protein-based toxins secreted by living gram-positive bacteria into their environment.

Endotoxins

Toxins made of lipids and carbohydrates associated with the outer membrane of gram-negative bacteria, released only when the bacteria die.

Broad spectrum antibiotics

Antibiotics that are effective against a wide variety of different organisms.