Prokaryotes: Bacteria and Archaea

This set of flashcards covers essential vocabulary and concepts from the lecture on prokaryotes, including their structure, diversity, and roles in ecosystems.

Koch's postulates

A set of criteria to establish a causative relationship between a microorganism and a disease.

Prokaryotes

Single-celled organisms that lack a nucleus, includes Bacteria and Archaea.

Extremophiles

Organisms that thrive in extreme environmental conditions.

Binary fission

A method of asexual reproduction in prokaryotes where the cell divides into two identical cells.

Gram-positive bacteria

Bacteria with a thick peptidoglycan layer that retain the purple stain.

Gram-negative bacteria

Bacteria with a thin peptidoglycan layer and an outer lipid bilayer, stain pink.

Plasmids

Small circular DNA molecules found in prokaryotes, distinct from chromosomal DNA.

Capsule

A sticky layer surrounding some prokaryotic cells that helps adhere to surfaces and protects from the immune system.

Fimbriae

Hair-like structures that help bacteria adhere to surfaces and each other.

Taxis

Directed movement toward or away from a stimulus in prokaryotes.

Photoautotrophs

Organisms that use light energy and carbon dioxide for growth.

Chemoheterotrophs

Organisms that obtain both energy and carbon from organic compounds.

Symbiosis

Interaction between two different organisms living in close physical proximity.

Mutualism

A type of symbiosis where both species benefit.

Parasitism

A type of symbiosis where one organism benefits at the expense of another.

Commensalism

A type of symbiosis where one organism benefits without affecting the other.

Cocci

Spherical-shaped prokaryotic cells.

Bacilli

Rod-shaped prokaryotic cells.

Spirilli

Spiral-shaped prokaryotic cells.

Nucleoid

The region in prokaryotic cells where the DNA is located, not surrounded by a membrane.

Peptidoglycan

A polymer that makes up the cell wall of bacteria.

Flagella

Long, whip-like structures that enable movement in many prokaryotes.

Exotoxins

Toxic proteins secreted by bacteria that can lead to disease.

Endotoxins

Toxins that are part of the outer membrane of certain bacteria and can cause systemic inflammation.

Micronutrients

Nutrients required in small amounts for microbial metabolism.

Macronutrients

Nutrients required in large amounts for microbial growth.

Hydrolyze

To break down a compound by reacting with water.

Transformation

The process of taking up foreign DNA from the environment.

Transduction

The process by which bacteriophages transfer DNA from one bacterium to another.

Conjugation

The process of transferring DNA between two bacterial cells through direct contact.

Endospores

Dormant, resistant bacterial structures that can survive extreme conditions.

Thermophiles

Heat-loving microorganisms adapted to high-temperature environments.

Acidophiles

Organisms that thrive in acidic environments (pH 3 or below).

Halophiles

Organisms that thrive in high salt concentrations.

Oligotrophic

Describing environments with low nutrient levels.

Bioremediation

The use of microorganisms to remove or neutralize contaminants from the environment.

Cyanobacteria

Photosynthetic bacteria that generate oxygen, also known as blue-green algae.

Nitrogen cycle

The process through which nitrogen is converted between its various chemical forms.

Carbon fixation

The process of converting inorganic carbon (CO2) into organic compounds.

Pathogenic bacteria

Bacteria that can cause disease in their hosts.

Microbial growth medium

A substance that provides the necessary nutrients for the growth of microorganisms.

Biofilm

A community of microorganisms embedded in a matrix of extracellular polymeric substances.

Decomposer

Organisms that break down dead organic material, returning nutrients to the ecosystem.

Ecology

The study of interactions among organisms and their environment.

Antibiotic resistance

The ability of bacteria to survive exposure to antibiotics that once killed them.

Biochemical diversity

Variability in biochemical processes among different prokaryotic species.

Bacteriophage

A virus that infects bacteria.

Microbiota

The community of microorganisms living in a specific environment, such as the human body.

Cellular respiration

The metabolic process by which cells convert glucose and oxygen into energy.

Fermentation

The metabolic process that converts sugars to acids, gases, or alcohol in the absence of oxygen.

Carbon cycle

The series of processes through which carbon compounds are interconverted in the environment.

Hydrologic cycle

The cycle of water movement through the environment.

Endemic

Native to a particular area or environment.

Zoonotic infection

Diseases that are transmitted from animals to humans.

Antigen

A molecule capable of inducing an immune response.

Vaccine

A biological preparation that provides active acquired immunity to a particular infectious disease.

Microbiome

The collection of all the microorganisms living in a particular environment.