MICROPARA - MODULE 1

Microbiology

Study of microorganisms, including bacteria, fungi, protozoa, algae, and viruses

Parasitology

Study of parasites and their relationship with hosts

Pathogen

Microorganism that causes disease

Normal Flora

Microorganisms normally present in or on the human body without causing disease

Opportunistic Pathogen

Microorganism that causes disease only when host defenses are compromised

Robert Hooke

Reported that life’s smallest structural units were “cells”; foundation of Cell Theory (1665)

Anton Van Leeuwenhoek

First to observe live microorganisms (“animalcules”) using single-lens microscope; Father of Microbiology (1673)

Spontaneous Generation

Disproven theory that living organisms could arise from nonliving matter (abiogenesis)

Francesco Redi

Disproved spontaneous generation with decaying meat and maggot experiment (1668)

John Needham

Claimed microorganisms appeared spontaneously in heated broth, supporting spontaneous generation (1745)

Lazzaro Spallanzani

Refuted Needham’s experiment; showed microbes entered broth from air contamination (1765)

Rudolf Virchow

Introduced concept of Biogenesis: living cells arise only from preexisting cells (1858)

Louis Pasteur

Disproved spontaneous generation with swan-neck flask experiment (1861); developed aseptic techniques, fermentation, pasteurization, vaccination

Golden Age of Microbiology

Period between 1857–1914 when major discoveries in microbiology occurred

Fermentation

Process where yeast converts sugars to alcohol; bacteria oxidize alcohol to acetic acid

Pasteurization

Heat process used to kill bacteria in milk and beverages

Germ Theory of Disease

Concept that specific microorganisms cause specific diseases (Pasteur, Bassi)

Joseph Lister

Father of Antiseptic Surgery; introduced phenol to sterilize surgical dressings and instruments (1860s)

Robert Koch

Developed Koch’s Postulates to prove specific microbes cause specific diseases; identified Bacillus anthracis as cause of anthrax

Koch’s Postulates

Experimental steps used to demonstrate a microorganism causes a disease

Edward Jenner

Developed first vaccine (1798) by using cowpox to protect against smallpox

John Tyndall

Discovered heat-resistant bacterial spores; developed tyndallization (fractional sterilization)

Ignaz Semmelweis

Father of Handwashing; reduced puerperal fever by introducing mandatory hand disinfection with chlorinated lime

Paul Ehrlich

Pioneer of chemotherapy; developed Salvarsan (arsphenamine, Compound 606) to treat syphilis (1910)

Alexander Fleming

Discovered penicillin from Penicillium mold (1928)

Howard Florey and Boris Chain

Purified penicillin for clinical use and conducted clinical trials (1940s)

Rene Dubos

Discovered first commercially available antibiotics (tyrocidine and gramicidin) in 1939

Rebecca Lancefield

Proposed classification system for streptococci based on cell wall antigens (1933)

Dmitri Iwanowski

Discovered viruses by showing tobacco mosaic disease passed through filters (1892)

Wendell Stanley

Crystallized tobacco mosaic virus and advanced study of viral chemistry

George Beadle and Edward Tatum

Proposed one gene–one enzyme hypothesis (1941)

Oswald Avery, Colin MacLeod, Maclyn McCarty

Demonstrated that DNA is the hereditary material (1944)

Joshua Lederberg and Edward Tatum

Discovered bacterial conjugation (1946)

James Watson and Francis Crick

Proposed double helix structure of DNA (1953)

Francois Jacob and Jacques Monod

Discovered mRNA and gene regulation in bacteria (1961)

Paul Berg

Created first recombinant DNA hybrid (animal or human DNA in bacterial DNA)

Bacteria

Unicellular prokaryotes with shapes bacillus (rod), coccus (round), or spiral; reproduce by binary fission; may have flagella

Archaea

Unicellular prokaryotes distinct from bacteria; different biochemistry and evolutionary history

Fungi

Eukaryotes; unicellular (yeast) or multicellular (molds); absorb nutrients from environment

Protozoa

Unicellular eukaryotes; obtain nutrients by ingestion or absorption; classified by locomotion

Algae

Unicellular or multicellular eukaryotes; photosynthetic; produce oxygen and carbohydrates

Viruses

Acellular; consist of nucleic acid core (DNA or RNA) surrounded by protein coat; obligate intracellular parasites

Helminths

Multicellular animal parasites (flatworms and roundworms); identified by microscopic stages

Prokaryotic Cell

Cell without nucleus; DNA in nucleoid; circular chromosomes

Eukaryotic Cell

Cell with nucleus, membrane-bound organelles, and linear chromosomes

Gram-Positive Cell Wall

Thick peptidoglycan layer, teichoic acids, no outer membrane; stain purple/blue in Gram stain

Gram-Negative Cell Wall

Thin peptidoglycan layer, outer membrane with lipopolysaccharide (endotoxin); stain pink/red in Gram stain

Flagella

Long threadlike appendages made of flagellin; provide motility (arrangements: monotrichous, lophotrichous, amphitrichous, peritrichous)

Fimbriae

Short, hairlike filaments for adherence to surfaces

Pili

Thin hairlike structures; sex pili allow DNA transfer during conjugation

Plasmid

Small, circular DNA molecules independent of bacterial chromosome; may carry antibiotic resistance genes

Endospores

Resting cells highly resistant to heat, dehydration, and chemicals; contain dipicolinic acid

Transposons

“Jumping genes” that move within or between DNA molecules