Biology basics & diversity of life · Topic 3 of 17

Microorganisms, Infectious Disease & Immunity

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Biology · microbes & disease

Bacteria, viruses, fungi and protists can cause disease; antibiotics work on bacteria only, while vaccines are the main defense against viruses.

01 · VirusVirus = DNA or RNA in a protein coat

02 · TreatmentAntibiotics: bacteria yes, viruses no

03 · ResistanceMisused antibiotics breed resistant bacteria

Pathogen = a disease-causing agent: bacteria, viruses, fungi, protists must know

Viruses multiply only inside a host cell, using the cell's machinery must know

Viral disease: prevented mainly by vaccines; a few antiviral drugs exist

Vaccine = weakened, killed or partial pathogen that builds immunity

Overused or unfinished antibiotics leave resistant bacteria to multiply

Bacterial diseases: strep throat, plague, botulism, some E. coli

Viral diseases: colds, flu, measles, chickenpox, hepatitis, HIV

Fungal infections: athlete's foot, ringworm (a fungus, not a worm), thrush

Protist diseases: malaria (Plasmodium, via mosquitoes), sleeping sickness

Virus = DNA or RNA inside a protein coat (capsid); far smaller than bacteria must know

Spread: contact, droplets, objects (fomites), food/water/air, vectors

Antibiotics treat bacterial infections — they do not work on viruses must know

Bacteria are living cells that reproduce on their own; viruses are not

Innate defense = fast, nonspecific; adaptive = specific, with memory

Commonly confused

Pearl

Antibiotics are for bacteria; viruses need a vaccine or an antiviral.

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