Microbiology Key Concepts: History, Microorganisms, and Applications

Environmental microbiology

Sergei Winogradsky and Martinus Beijerinck

Biochemistry

Eduard Buchner and Louis Pasteur

Chemotherapy

Paul Ehrlich

Immunology

Edward Jenner

Infection control

Joseph Lister and Ignaz Semmelweis

Etiology

Robert Koch

Epidemiology

John Snow

Biotechnology

Martinus Beijerinck and Sergei Winogradsky

Food microbiology

Louis Pasteur

Established germ theory and modern microbiology

Pasteur

Developed smallpox immunization

Edward Jenner

First photomicrograph of bacteria

Robert Koch

Used mathematical data to improve nursing

Florence Nightingale

Germs cause disease

Girolamo Fracastoro

Sought a "magic bullet" to destroy pathogens

Paul Ehrlich

Early epidemiologist

John Snow

Father of Microbiology

Louis Pasteur

Classification system

Carolus Linnaeus

Discoverer of bacteria and protozoa

Antoni van Leeuwenhoek

Founder of antiseptic surgery

Joseph Lister

Developed the most widely used bacterial staining technique

Hans Christian Gram

Microorganisms that are not eukaryotic

Bacteria

Microorganisms used to make microbiological growth media

Algae

Habitats where archaea are commonly found

acidic hot springs, swamp mud; Great Salt Lake

Scientist who first proposed the theory of abiogenesis was

Aristotle

The scientist who first suggested that medical personnel can transmit pathogens to patients was

Ignaz Semmelweis

Term used by van Leeuwenhoek to describe microorganisms

Animalcules

Scientist who supported the theory of spontaneous generation

Needham

Scientist who studies the role of microorganisms in the environment

an environmental microbiologist

Contributions of Robert Koch's laboratory to microbiology

Simple staining technique; use of Petri dishes; first photomicrograph of bacteria

Why was the theory of spontaneous generation a hindrance to microbiology?

It incorrectly suggested that microorganisms arose spontaneously rather than from existing microbes.

How did Pasteur's flask differ from Spallanzani's and how did it settle the spontaneous generation debate?

Pasteur used a swan-neck flask that allowed air in but trapped microbes, proving microbes come from contamination.

Six types of microorganisms

Bacteria; archaea; fungi; protozoa; algae; viruses

Why did van Leeuwenhoek's investigations change the world forever?

He was the first to observe and describe microorganisms.

Why would a macroscopic tapeworm be studied in microbiology?

Because microbiology includes disease-causing parasites.

What was the Golden Age of Microbiology?

A period of rapid discoveries about microbes, disease, immunity, and industrial applications.

Four major questions that drove microbiology during the Golden Age

What causes disease?; How can disease be prevented?; What causes fermentation?; What role do microbes play in the environment?

How did Pasteur use the scientific method in his fermentation experiments?

He observed fermentation, formed a hypothesis, tested it experimentally, and analyzed the results.

What are Koch's postulates?

The microbe must be found in diseased hosts; isolated and cultured; cause disease in a healthy host; and be re-isolated from the newly diseased host.

Why are Koch's postulates significant?

They helped prove that specific microbes cause specific diseases.

What does HAI (nosocomial infection) have to do with patient care?

It is an infection acquired while receiving healthcare.

How would Koch's accomplishments have differed if he studied influenza instead of anthrax?

Viruses could not be seen or cultured with the technology of his time, making discoveries more difficult.

Why did scientists criticize Funk's theory about beriberi?

They believed diseases were caused by microbes and expected him to find a microorganism.

How could Koch's postulates have prevented the naming error of Haemophilus influenzae?

They would have shown that H. influenzae does not cause influenza.

Why is it unreasonable to expect pasteurized milk to never spoil?

Pasteurization reduces microbes but does not eliminate all of them.

How can you demonstrate that microbes do not spontaneously generate in milk?

Boil milk in two containers, seal one and leave the other open; only the open milk will spoil.

How could an epidemiologist test the nocturnal vapor theory of cholera?

Compare disease cases with water sources and vapor exposure.

How did Redi, Needham, Spallanzani, and Pasteur contribute to the spontaneous generation debate?

Redi and Pasteur disproved it; Needham supported it; Spallanzani provided evidence against it.

Name three disciplines in applied microbiology.

Medical microbiology; industrial microbiology; agricultural microbiology

Why don't algae typically cause disease?

They make their own food and do not rely on human tissues for nutrients.

How might Buchner's work have affected the spontaneous generation debate if done in 1857?

It may have been used as evidence supporting spontaneous generation.

What advantage did Koch's method have over the French dilution method?

It allowed isolation of pure cultures from individual colonies.

Why are Koch's postulates not always useful?

Some diseases are viral, genetic, environmental, or have multiple causes.

What did Kluyver mean by "From elephant to bacterium—it is all the same"?

All living things share basic biochemical processes.

How could Beijerinck's discovery help increase grain production?

Nitrogen-fixing bacteria can improve soil fertility and crop yields.

Why could both van Leeuwenhoek and Pasteur be called the father of microbiology?

Van Leeuwenhoek discovered microorganisms; Pasteur established modern microbiology.

List three main types of chemical bonds and give an example of each

Covalent bond — sharing electrons (ex: water)

Ionic bond — electron transfer (ex: NaCl)

Hydrogen bond — weak attraction (ex: between water molecules)

Name five properties of water that are vital to life

Cohesion,Adhesion High heat capacity Universal solvent Ice less dense than liquid water

Describe the difference(s) among saturated fatty acids unsaturated fatty acids and polyunsaturated fatty acids

Saturated: no double bonds (solid fats) Unsaturated: one double bond Polyunsaturated: multiple double bonds

What is the difference between atomic oxygen and molecular oxygen?

Atomic oxygen (O) = single oxygen atom Molecular oxygen (O₂) = two oxygen atoms bonded

Explain how the polarity of water molecules makes water an excellent solvent

Water is polar (partial + and − ends), so it surrounds and separates ions/molecules → dissolves them easily.

What are phosphorus sulfur iron and magnesium used for in microbial metabolism?

Phosphorus is used in ATP and DNA; sulfur in amino acids; iron in electron transport proteins; magnesium as an enzyme cofactor.

Why aren't many antimicrobial drugs directed at bacterial cytoplasmic membranes?

Because bacterial and human cell membranes are very similar, making selective targeting difficult.

How does a noncompetitive inhibitor limit enzyme activity?

It binds to a site other than the active site and changes the enzyme's shape.

How are bacteria archaea fungi protozoa algae and viruses distinguished by cellular structure?

Bacteria and archaea are prokaryotes; fungi, protozoa, and algae are eukaryotes; viruses are acellular.

How do enzymes work and what factors affect enzyme activity?

Enzymes lower activation energy; activity is affected by temperature, pH, substrate concentration, and inhibitors.

Why is feedback inhibition important in anabolic pathways?

It prevents the cell from wasting energy by making excess product.

What is the main product of the light-dependent reactions of photosynthesis?

ATP and NADPH.

How is ribulose-15-bisphosphate used in the Calvin-Benson cycle?

It combines with CO₂ to begin carbon fixation.

What roles do NADH and FADH₂ serve in catabolism?

They carry high-energy electrons to the electron transport chain.

How can oxidation occur in an anaerobic environment?

Electrons can be transferred to molecules other than oxygen.

Why is Mycoplasma considered alive even though it cannot move?

It can grow, reproduce, metabolize, and respond to its environment.

How do archaeal flagella differ from bacterial and eukaryotic flagella?

Archaeal flagella are structurally unique and are more similar to pili than bacterial flagella.

Why are neon and argon inert?

They have full outer electron shells, making them chemically stable and unlikely to form bonds.

What is the electron configuration of neon?

2,8

What is the electron configuration of argon?

2,8,8

List 8 differences between Streptococcus pyogenes and Entamoeba histolytica.

S. pyogenes is prokaryotic; lacks a nucleus, lacks membrane-bound organelles, has peptidoglycan cell walls, reproduces by binary fission, smaller, circular DNA, unicellular

E. histolytica is eukaryotic; has a nucleus; has organelles; lacks peptidoglycan; reproduces by mitosis; larger; linear chromosomes; more complex cell structure.

What do chloroplasts use light energy to produce?

ATP and carbohydrates

What molecules are found in all cell membranes?

Phospholipids and proteins

What subunits make up eukaryotic ribosomes?

60S and 40S subunits

What organelle is formed by the endocytosis of food particles in eukaryotic cells?

Lysosome

What is chromatin composed of?

DNA and histone proteins

Does facilitated diffusion require an input of energy?

No

Can bacterial protein synthesis begin before gene transcription is complete?

Yes

What is the function of the Golgi body?

Prepares cellular products for export

What do peroxisomes contain?

Enzymes that break down fatty acids and toxins

What are Svedbergs used to measure?

The size and sedimentation rate of cellular structures

Cell surface markers composed of both carbohydrate and lipid molecules are called

Glycolipids

Another name for a unit of atomic mass

Dalton

The folding of a polypeptide into a three-dimensional shape is its

Tertiary structure

A molecule that speeds up a chemical reaction

Catalyst

The reverse of dehydration synthesis

Hydrolysis

A substance that maintains pH despite changes in acid or base concentration

Buffer

Forms of an element that differ in the number of neutrons

Isotopes

The sum of all chemical reactions within an organism

Metabolism

A molecule that binds hydrogen ions when dissolved in water

Base

Involves the production of cell membrane constituents. Is endergonic. Includes dehydration synthesis reactions

Anabolism only

Includes hydrolytic reactions. Is exergonic. Breaks a large molecule into smaller ones

Catabolism only

Includes metabolism

Both anabolism and catabolism (amphibolic)

What do redox reactions do?

Transfer energy; transfer electrons; involve oxidation and reduction