EXAM #1 (Ch. 1, 5, 7)

SPR26 OSU MICROBIO

organisms that are too small to be seen with the unaided eye

microorganisms (“microbes”)

the study of microscopic organisms, such as bacteria, viruses, archaea, fungi, and protozoa

microbiology

what fundamental research is included in microbiology

biochemistry, physiology, cell biology, ecology, evolution & clinical aspects & host response of microorganisms

the foundation of all life on earth (still critical for environmental maintenance)

microbes

pathogen definition

cause infection & disease w/in a host

a few microbes can act as ____, but most are harmless or even beneficial

pathogens

scientists believe we have yet to discover _____ of all species of microbes, and most of the study thus far has been related to _____.

• 99.999%

• human life

3 general types of microbes

1. prokaryotes

2. eukaryotes

3. noncellular (or acellular) agents

key difference b/t prokaryote and eukaryote?

prokaryote has no true nucleus or nuclear membrane, and a eukaryote has a membrane-bound nucleus

2 types of prokaryotes

bacteria and archaea

4 types of eukaryotes

• protozoa

• algae

• fungi

• helminths

single/unicellular microbes

• bacteria

• archaea

• protozoa

single and multicellular microbes

• algae

• fungi

microbes with organics only food source

• fungi

• helminths

microbe with photosynthesis as an only food source

algae

microbes w/ photosynthesis as part (or only) food source

• algae

• bacteria

• protozoa (a few)

microbes with inorganic food sources

• bacteria

• archaea

microbes with organic food sources

• bacteria

• archaea

• protozoa

• fungi

• helminths

microbes w/ cell walls (typically)

• bacteria

• archaea

• algae

• fungi

microbes w/ no cell walls

• protozoa

• helminths

microbes that can (sometimes or always) act as a pathogen

• bacteria (some)

• protozoa (some)

• fungi (some)

• helminths

• viruses, viroids, prions

microbes w/ single cell motility

• bacteria (often)

• archaea (often)

• protozoa (often)

• algae (some)

• fungi (a few)

an organism, typically a microorganism, that thrives in physically or geochemically extreme conditions that are detrimental to most life

extremophile

microbes that can be extremophiles

• bacteria

• archaea (most are)

• protozoa, algae, fungi, and helminths (very rarely, only a few)

microbes w/ DNA

• bacteria

• archaea

• protozoa

• algae

• fungi

• helminths

• viruses, viroids, prions (have a mixture, but yes)

microbes w/ RNA

viruses, viroids, and prions (DNA, RNA, or none)

what are the cell walls of bacteria made of

peptidoglycan

these things help with motility

• flagella

• cilia

• pseudopods

• pili

many protozoa are ___ living

free

some protozoa’s are _____ (benefit from, but cause harm to, host)

parasitic

algae are sometimes ____ w/ aquatic invertebrae

symbiotic

although algae are not pathogens, they can _____ in environments.

release toxins

what are some commons ways that fungi are used

yeasts in bread and beer brewing

mycology is the study of

fungi biology

helminths constitute _____ w/ some being macroscopic or visible by the human eye

highly infectious flatworms and roundworms

some microbial infectious agents are ___ and ____; they cannot replicate outside a living host.

• noncellular

• nonmetabolic

virus is a DNA or RNA genome surrounded by a ____

protein capsid

the protein capsid of a virus may be enclosed in a _____.

lipid envelope

virology is the study of what

viruses

viruses are _____ outside a living host

inert

viroids definition

not a true “virus”, but an infectious RNA (only, no proteins)

prions definition

not a virus, but an infectious protein (no RNA, DNA, genome)

food and drink are produced by _____ as far back as 10,000 BCE

microbial fermentation

_________ such as TB, polio, smallpox, and leprosy profoundly affected human demographics and cultural practices

microbial diseases

by 1100 CE, some diseases were understood to be _____, but disease was often attributed to bad air _____, supernatural forces or bodily imbalances.

• contagious

• “miasma”

_____ build the first compound microscope and coined the term “cells”.

robert hook

_______ observed smaller organisms and bacteria with a stronger, single-lens microscope.

anton van leeuwenhoek

who is the “father of microbiology”

Anton van Leeuwenhoek

____ the idea that things or cells just appeared out of nothing

spontaneous generation

who showed bacteria were living things capable of reproducing and potentially as a cause of disease

Louis Pasteur

with his S-flask experiment, Louis Pasteur proved biogenesis, which is _______

the idea that biological growth comes from microbes or other biological organisms

major discoveries during the Golden Age of Microbiology

• microbial causes behind fermentation & infectious diseases

• staining technique

• lithotrophy and nitrogen fixation

germ theory of disease

specific diseases are caused by specific microscopic “germs”/microbes

epidemiology

meticulous record keeping and stats to uncover how diseases were spreading

____ common in overcrowded areas like cities and during warfare

disease

____, not poor nutrition, was the leading cause of soldier death

infection

koch’s postulates

scientific method/criteria developed by Robert Koch used to determine if a specific microorganism/pathogen causes a specific disease

pure colony

grown from a single colony of bacteria and were crucial for Robert Koch to establish his postulates (isolated strains)

germ theory led to breakthroughs in disease prevention, such as,

handwashing, antiseptics, disinfection, sanitation, sewage and water treatment

antimicrobial drug Salvarsan

first chemical developed to treat bacterial infections such as syphilis

antibiotic penicillin

first natural antimicrobial drug used to treat bacterial infections

What was variolation?

Early smallpox prevention (≥1000 BCE) involving exposure to material from smallpox lesions.

What did Edward Jenner demonstrate in 1796?

Cowpox exposure protected against smallpox with much lower risk than variolation.

Who coined the term “vaccination”?

Louis Pasteur.

What was Pasteur’s key contribution to vaccination?

Use of attenuated (weakened) bacteria to induce immunity without severe disease (1870s–1880s).

What was the Theory of Immunity (1910s)?

The idea that humans produce specific compounds, called antibodies, to fight pathogens.

What major vaccination developments occurred in the mid–late 1900s?

Widespread public vaccination programs (influenza, polio, MMR) and global smallpox eradication.

What are still some limitations of vaccines and antibiotics today?

• diseases can become resistant to treatment

• not possible to get everyone vaccinated

• distribution issues

• always new diseases popping up

What advance in the 1880s allowed selective growth of microbes?

Use of culture media to grow specific microbes while excluding others.

What are lithotrophs?

Bacteria that obtain energy from inorganic molecules.

Why are microbes ecologically important?

• nutrient cycling (N, S, P, etc.)

• C-fixation

• O-generation

• primary producers

• water filtration (in aquatic food webs)

What major ecological roles do microbes play w/in nutrient cycles?

drive cycling of inorganic & organic N, S, P, & other elements.

Why are microbes foundational to ecosystems?

They perform most carbon fixation and oxygen generation, act as primary producers, and filter water in aquatic food webs.

What role do bacteria play as digestive endosymbionts?

They help animals digest plant polymers (e.g., cattle, termites).

What is the human microbiota?

The community of microorganisms living in and on the human body.

How does the human microbiota benefit the host?

Aids digestion, trains the immune system, produces vitamins (B, K), and provides colonization-resistance against pathogens.

What is colonization resistance?

Prevention of pathogen growth through competition by resident microbes.

What is still unknown about the human microbiota?

Many functions and interactions remain poorly understood.

Why are microbes important as model systems in molecular biology?

They are used to answer fundamental molecular biology questions due to their simplicity and genetic accessibility.

How did understanding DNA structure influence molecular biology?

DNA structure discovery (1950s) enabled development of DNA sequencing (1970s).

What was Carl Woese’s major contribution to biology?

Discovery of archaea and proposal of the three-domain system based on rRNA sequences (1970s).

What was the first cellular genome sequenced?

A bacterial genome (1995).

What is metagenomics?

High-throughput sequencing of entire microbial communities.

Which modern molecular tools originated from microbiology research?

Viral vectors for gene therapy and CRISPR genome editing.

In how many domains of life do microbes exist?

All three domains: Bacteria, Archaea, and Eukarya.

Who proposed the three-domain system of life and when?

Carl Woese, 1977.

What do scientists compare today to study organisms and their relationships?

Genomes—the complete DNA content of each organism.

What is a species in microbiology?

A type of organism (or group of strains) defined by a shared set of genes and traits.

What is binomial naming?

The two-part scientific name of an organism: Genus + species.

What is a strain?

A genetic variant within a species.

What do microbiologists do today?

They study microbes using genomic, molecular, and ecological approaches to understand health, disease, biotechnology, and environmental processes.

Are there exceptions to prokaryote and eukaryote “rules”?

Yes. Biological classifications have exceptions; traits vary across organisms, and rules describe general trends, not absolutes.

ID this cellular morphology

Bacilli — rods

ID this cellular morphology

spirochetes — long corkscrew

ID this cellular morphology

cocci — spheres

ID this cellular morphology

vibrio — commas

ID this cellular morphology

spirilla — short spirals or helical

spirilla vs. spirochete

• spirilla: shorter, rigid, external, flagella

• spirochete: longer, flexible, axial filament

What determines bacterial cell arrangements?

The plane of cell division.

What are bacterial arrangements based on observationally?

What scientists see under the microscope.