Microorganisms: Friend and Foe – Key Vocabulary

Vocabulary flashcards covering essential terms related to microorganisms, their roles, and applications from the lecture notes.

Microorganism (Microbe)

A living organism too small to be seen with the unaided eye; includes bacteria, fungi, protozoa, some algae, and viruses.

Bacteria

Single-celled prokaryotic microbes that may be helpful (curd formation, nitrogen fixation) or harmful (typhoid, TB).

Fungi

A group of mostly multicellular, spore-producing microbes such as moulds, Penicillium, and yeast; some spoil food while others make antibiotics.

Protozoa

Single-celled, animal-like microbes (e.g., Amoeba, Plasmodium) that can cause diseases like malaria and dysentery.

Algae

Plant-like, photosynthetic microbes (e.g., Chlamydomonas, Spirogyra); some fix nitrogen in soil.

Virus

A microscopic infectious agent that can reproduce only inside the cells of a host organism; causes diseases like flu, polio, and chicken pox.

Yeast

A unicellular fungus used in baking and brewing; ferments sugars to produce alcohol and carbon dioxide.

Lactobacillus

A bacterium that converts milk into curd by fermenting lactose sugar.

Rhizobium

Nitrogen-fixing bacterium that lives symbiotically inside root nodules of leguminous plants.

Symbiotic Relationship

A close association between two different organisms in which both may benefit, as in Rhizobium and legumes.

Nitrogen Fixation

Conversion of atmospheric nitrogen gas into usable nitrogen compounds by bacteria, blue-green algae, or lightning.

Nitrogen Cycle

The continuous movement of nitrogen through the atmosphere, soil, plants, animals, and back, involving fixation, uptake, decomposition, and denitrification.

Pathogen

A disease-causing microorganism such as certain bacteria, viruses, protozoa, or fungi.

Communicable Disease

An illness that can spread from an infected person to a healthy person through air, water, food, contact, or vectors.

Carrier (Vector)

An organism that transmits pathogens without suffering from the disease itself, e.g., housefly, female Anopheles mosquito.

Female Anopheles Mosquito

Vector that carries the protozoan Plasmodium, causing malaria.

Female Aedes Mosquito

Vector responsible for spreading dengue virus.

Fermentation

The conversion of sugars into alcohol and carbon dioxide by microorganisms such as yeast; discovered by Louis Pasteur.

Antibiotic

A medicine produced by microbes (e.g., penicillin, streptomycin) that kills or inhibits other microorganisms.

Penicillin

The first antibiotic discovered (by Alexander Fleming) from the mould Penicillium; inhibits bacterial growth.

Vaccine

A preparation of weakened or dead pathogens that stimulates the body to produce protective antibodies.

Pulse Polio Programme

Mass immunisation campaign in India that gives oral polio vaccine drops to eradicate polio.

Pasteurisation

Heat treatment of milk at about 70 °C for 15–30 s followed by rapid cooling to kill harmful microbes without affecting taste.

Food Preservation

Methods used to prevent spoilage and microbial growth in food, such as salting, sugaring, oil/vinegar, refrigeration, and canning.

Common Salt Preservation

Traditional method where high salt concentration inhibits microbial growth in meat, fish, and pickles.

Sugar Preservation

Use of high sugar concentration in jams and jellies to bind moisture and stop microbial activity.

Oil and Vinegar Preservation

Technique where acidic or oily environment prevents bacteria from surviving in pickles and sauces.

Food Poisoning

Illness caused by ingesting food contaminated with toxin-producing microorganisms.

Biological Nitrogen Fixers

Microbes (e.g., Rhizobium, cyanobacteria) that enrich soil by converting atmospheric nitrogen into nitrates.

Blue-Green Algae (Cyanobacteria)

Photosynthetic bacteria capable of nitrogen fixation; improve soil fertility.

Housefly

Common insect vector that transfers pathogens from garbage or excreta to uncovered food, causing diseases like cholera.

Anthrax

A serious disease of humans and cattle caused by the bacterium Bacillus anthracis; discovered by Robert Koch.

Pasteur, Louis

Scientist who discovered fermentation and developed pasteurisation, contributing to microbiology and immunology.

Fleming, Alexander

Discovered the antibiotic penicillin in 1929 when mould inhibited bacterial growth on culture plates.

Preservative

A chemical (e.g., sodium benzoate, sodium metabisulphite) added to food to inhibit microbial spoilage.