Chapter 1–6 Key Vocabulary: Symbiosis, Pathogens, and Conservation

A set of vocabulary flashcards covering key terms from the lecture notes on symbiosis, nitrogen fixation, bacterial toxins, immune responses, and related conservation programs.

Symbiosis

A close, long-term interaction between two different species, which can be mutualistic, parasitic, or commensal.

Mutualism

A symbiotic relationship in which both participating species benefit.

Parasitism

A symbiotic relationship where one species benefits at the expense of the other.

Commensalism

A symbiotic relationship in which one species benefits and the other is unaffected.

Termite gut mutualism (cellulose digestion)

Bacteria/archaea in termite guts digest cellulose, providing digestion help to the host while gaining a stable, nutrient-rich niche.

Fermentation

A metabolism that converts sugars to end products (e.g., acetate) without using an electron transport chain.

Cellulose

A complex plant fiber that certain microbes break down and ferment.

Nitrogen fixation

Biological conversion of atmospheric nitrogen (N2) into ammonia (NH3), making nitrogen biologically available.

Nitrogenase

The bacterial enzyme complex that reduces N2 to NH3 during nitrogen fixation.

Ammonia (NH3)

Biologically usable form of nitrogen produced by nitrogen fixation.

Nodule

Root structure in legumes that houses nitrogen-fixing bacteria (rhizobia) in a mutualistic relationship.

Rhizobia

Nitrogen-fixing bacteria that form symbiotic nodules on legume roots.

Legume

A plant family (peas, beans, clover, etc.) that forms nodules with rhizobia for nitrogen fixation.

Flavonoids

Plant-produced signals that attract rhizobia to the roots of legumes.

Nod factors

Bacterial signaling molecules that trigger plant responses and initiate nodulation.

Infection thread

A tubular structure through which rhizobia invade the plant root hair and reach the nodule.

Bacteroids

Differentiated nitrogen-fixing bacteria inside plant nodules.

Leghemoglobin

Oxygen-carrying protein in legume nodules that maintains a microaerobic environment for nitrogenase.

Microaerobic environment

Low-oxygen conditions that allow nitrogenase activity while keeping rhizobia alive.

Free-living nitrogen-fixing bacteria

Nitrogen-fixers that live in soil or water outside a plant root system.

Exotoxin

A toxin protein secreted by bacteria that can damage host tissues at distant sites.

Botulinum toxin

A potent exotoxin produced by Clostridium botulinum; used medically as Botox and in research.

Cholera toxin

Exotoxin produced by Vibrio cholerae; causes severe diarrhea by disrupting intestinal signaling.

Diphtheria toxin

Exotoxin produced by Corynebacterium diphtheriae that damages tissues; neutralized by vaccination.

Anthrax toxin

Exotoxin produced by Bacillus anthracis that contributes to disease.

Tetanus toxin

Exotoxin produced by Clostridium tetani that disrupts nervous system signaling.

Firmicutes

A phylum of Gram-positive bacteria that includes many spore-formers (e.g., Bacillus, Clostridium) and several exotoxins.

Actinobacteria

A Gram-positive, high-GC-content bacterial phylum that includes Corynebacterium and Streptomyces.

Corynebacterium

Gram-positive bacterium that can produce the diphtheria toxin and cause throat infections.

Streptomyces

An Actinobacteria genus known for producing many antibiotics.

Endotoxin (LPS)

A component of the outer membrane of Gram-negative bacteria (lipopolysaccharide) that can trigger systemic immune responses.

Endotoxin effects

Fever, vomiting, diarrhea, and systemic inflammation caused by an overactive immune response to LPS.

Koch’s postulates

Historical criteria used to establish a causal relationship between a microbe and a disease.

Vaccination

Immunization that educates the immune system to recognize and neutralize toxins or pathogens.

International Research Experience for Students (IRES)

NSF-funded program offering funded field-based research experiences for students (example: Grenada conservation project).

Grenada (island)

Southern Caribbean island where the conservation field program operates, featuring reefs, forests, and endemic species.

Marine Protected Areas (MPAs)

Coastal or marine regions designated for conservation to protect biodiversity and ecosystem health.

Reef monitoring program

Long-running project measuring reef health, temperature, and biodiversity to inform conservation policy.

Leatherback sea turtle nesting sites

Monitoring and protection activities focused on leatherback turtle nests to reduce poaching and improve conservation outcomes.

Grenada frog (endemic)

Critically endangered tree frog species found on Grenada; monitored for population trends.

Ocean Spirits (NGO)

NGO that collaborates with researchers and communities to monitor turtle nests and promote conservation.