Exam 1 Micro

What is fermentation?

a process in which bacteria, mold, or yeast convert sugars/carbohydrates into alcohol, gases, and organic acids

What is pasteurization?

a process in which microorganisms that cause food to spoil are killed

How are fermentation and pasteurization related to food safety and disease?

Pasteurization kills microorganisms that can cause spoilage and disease, helping make food safer

How did ancient people explain the causes of disease before microscopes?

Hippocrates suggested disease could come from the environment, while Marcus Terentius Varro suggested disease could be caused by things we cannot see

What are “animalcules”?

the term Leeuwenhoek used to describe the microorganisms he observed

What was the Golden Age of Microbiology?

1857–1914. major discoveries about microorganisms and disease were made

What bacterium causes anthrax according to the study guide?

Bacillus anthracis

What bacterium causes cholera according to the study guide?

Vibrio cholera.

What bacterium causes tuberculosis according to the study guide?

Mycobacterium tuberculosis

What was the historical system of taxonomy?

Historically, organisms were classified into three kingdoms: animal, plant, and mineral. The mineral kingdom was later removed.

What are the levels of the historical taxonomic hierarchy?

Kingdom, Class, Order, Family, Genus, Species.

What does modern taxonomy add above kingdom?

domain

What are the three domains of life?

Bacteria, Archaea, and Eukaryotes

What are the rules for scientific naming?

the genus and specific epithet. The genus is capitalized, and both names are italicized

What are some beneficial and harmful effects of bacteria?

Some bacteria are helpful, while others can cause disease.

What is important to know about archaea and human disease?

Archaea can live in extreme and normal environments, but they have no known human pathogens

What are algae?

can be unicellular or multicellular and are photosynthetic

What are protozoa?

generally larger than prokaryotes. They can be photosynthetic or feed on organic material. Most are harmless, but some can cause disease.

What are fungi?

can be unicellular or multicellular and have cell walls made of chitin rather than cellulose

What are helminths?

worms that can generally be seen with the naked eye. Their eggs and larvae can cause disease and infection.

What are viruses?

Viruses are acellular, meaning they are not made of cells. They contain proteins and genetic material and can cause diseases.

Give an example of a bacterium.

E. coli

Give an example of an archaeon.

Methanogens

Give an example of algae.

Diatoms

Give an example of a protozoan.

Amoeba

Give an example of a fungus.

Yeast

Give an example of a helminth.

Tapeworms

Give an example of a virus

COVID

What are similarities between archaea and bacteria?

Both are prokaryotic and can live in a variety of environments

How are archaeal and bacterial cell walls different?

archaea have pseudopeptidoglycan, while bacteria have peptidoglycan

What is unique about bacterial cell walls?

Bacterial cell walls contain peptidoglycan. Human cells do not have peptidoglycan, making it an important target for some antibiotics

What is bacteriology?

The study of bacteria.

What is mycology?

The study of fungi

What is protozoology?

The study of protozoa

What is parasitology?

The study of helminths and other parasites

What is virology?

The study of viruses

What is immunology?

The study of the immune system

What is resolution?

The ability to tell that two separate points or objects are actually separate

What is refraction?

The change in direction of light waves when they enter a new medium

What is diffraction?

The bending or spreading of light waves around or through obstacles

What is contrast?

The difference between light and dark areas that allows structures to be seen

What is magnification?

The ability of a lens to enlarge the image of an object compared with its actual size

What is the path of light through a compound microscope?

Illuminator, condenser, stage/specimen, objective lenses

What is the difference between a simple and compound microscope?

A simple microscope generally has one lens, while a compound microscope has two or more lenses.

What is the illuminator?

The light source of the microscope.

What are objective lenses?

Lenses with different magnifications that make the image larger.

What is the stage?

The platform where the specimen is placed

What do stage knobs do?

They move the stage forward/backward and side to side

What does the coarse adjustment knob do?

It moves the stage up and down quickly to help bring the specimen into focus

What does the fine adjustment knob do?

It moves the stage up and down to make small focusing adjustments

What does the condenser do?

It focuses light rays onto the specimen.

What does the diaphragm do?

It adjusts the amount of light reaching the specimen

How do you calculate total magnification?

Ocular magnification × objective magnification = total magnification.

What is the total magnification with a 10× ocular and 4× objective?

40x

What is the total magnification with a 10× ocular and 10× objective?

100x

What is the total magnification with a 10× ocular and 40× objective?

400x

What is the total magnification with a 10× ocular and 100× objective?

1000x

What is a brightfield microscope?

A common microscope with two or more lenses and four objectives. dark image against a bright background and can view objects as small as bacteria

What is a darkfield microscope?

It is similar to a brightfield microscope but has a modified condenser with a small opaque disk. It produces unstained cells against a dark background.

What is a fluorescence microscope?

It uses fluorochromes to create contrast. Chlorophylls can also create contrast, and fluorescence microscopy can be used in immunofluorescence.

What is phase-contrast microscopy used for?

Refraction produces images with high contrast and resolution. It can be used to view live specimens.

What are electron microscopes?

Microscopes that use electron beams instead of light and can achieve approximately 100,000×–2,000,000× magnification. They can be used to view viruses.

Why are electron microscopes more powerful than light microscopes?

They use electron beams with much shorter wavelengths than visible light, allowing greater magnification and resolution

What is the purpose of immersion oil?

helps more of the light from the specimen reach the objective lens, improving image clarity and resolution.

What problem does immersion oil remedy?

Without immersion oil, the image can be unclear and have poor resolution

What is a simple stain?

A stain that uses one dye and typically makes everything the same color

What is a differential stain?

A stain that uses multiple stains to differentiate organisms based on how they react to the stains

What is a basic dye?

A dye in which the chromophore is positively charged

What is an acidic dye?

A dye in which the chromophore is negatively charged

What is a negative stain?

A staining method in which the background absorbs the dye rather than the specimen

What is the purpose of fixing a slide?

attaches the cells of the specimen to the slide.

What type of stain does not require heat fixation according to the study guide?

Negative staining

What is the purpose of the Gram stain?

It is used to distinguish bacteria based on how they react to the staining process

What is the first step of the Gram stain?

Apply crystal violet to a heat-fixed smear. The cells become purple

What is the mordant used in the Gram stain?

Gram's iodine. It helps the crystal violet stay associated with the peptidoglycan layer

What does the decolorizer do in a Gram stain?

removes more stain from thin peptidoglycan layers and less from thick peptidoglycan layers

What is the counterstain used in Gram staining?

Safranin. It stains the decolorized cells pink

What are the four major Gram stain reagents in order?

Crystal violet, Gram's iodine, ethanol/acetone, safranin

What method is used for endospore staining?

The Schaeffer-Fulton method

What dye is used for endospore staining?

Malachite green

Why is heat used in endospore staining?

Heat is used to help push malachite green into the endospore

What happens when water is added during endospore staining?

The cell decolorizes, but the endospore remains green

What is the counterstain in endospore staining?

Safranin

What is the purpose of endospore staining?

To differentiate endospores from the rest of the bacterial cell

What is the Ziehl-Neelsen method?

An acid-fast staining method in which heat is used to help insert carbolfuchsin.

What is the Kinyoun method?

An acid-fast staining method that does not use heat

What dye is used in acid-fast staining?

Carbolfuchsin

What is unique about acid-fast bacterial cell walls?

They have a waxy layer containing mycolic acid on the outside

What happens during capsule staining?

The background is stained, but the capsule is not, causing the capsule to appear as a halo

Why are capsules important clinically?

Capsules are related to a microbe's ability to cause disease, so capsule staining can help identify organisms associated with disease

How is flagella staining performed?

A mordant coats the flagella, and then pararosaniline or fuchsin is used to stain them

What is the purpose of flagella staining?

To make flagella visible under the microscope

What is spontaneous generation?

The idea that life can come from nonliving matter, such as the belief that maggots could arise from meat

Why did people once accept spontaneous generation?

People observed that when certain materials were exposed to air, organisms seemed to appear, so they believed that life formed from nonliving material

How did Louis Pasteur disprove spontaneous generation?

used swan-neck flasks

What were Pasteur's swan-neck flasks?

Flasks with curved necks that allowed air to enter while preventing microorganisms from reaching the liquid inside

What is biogenesis?

The idea that all cells come from other cells

What is one major point of cell theory?

Cells are the fundamental units of organisms

What did Robert Hooke observe?

He observed cells that looked like a “honeycomb.”

What is the endosymbiotic theory?

The theory states that mitochondria and chloroplasts arose when prokaryotic cells established a symbiotic relationship inside a eukaryotic host cell