Exam 1 review Flashcards by Annabel Chambers

study of microorganisms or microbes

microbiology

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typically thought of as
microscopic organisms (not all are
microscopic however!

microbes

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Very small, relatively simple, single-
celled
 Prokaryotic cells
 Ubiquitous in nature (found everywhere)
 Absorb nutrients from their environment
 Diverse metabolic capabilities
 Reproduce by Binary Fission – relatively
simple duplication, making identical
daughter cells
 Some like Escherichia coli can divide every 20 minutes. In just seven
hours one can generate
2,097,152 !
 Some are pathogens, even though less
than 1% of all known are

bacteria

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Very small, simple, exist as single cells (though
can form groups, like bacteria)
 Prokaryotic
 Initially considered “extremophiles” because
some live in extreme environments
 Bottom of the ocean, in lakes full of sulfuric acid, hot
springs, etc.
 Not known to be pathogenic, many are part of our
normal flora
 Normal flora are all of the microbes that live in
and on our bodies
 More closely related to eukaryotic cells like us
than other prokaryotic cells like bacteria!
 only discovered in 1970s! We have much
to learn

Archaea

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Eukaryotic cells
 Most are microscopic, single-celled
organisms, but some are large, multicellular organisms
 Autotrophic protists (unlike the
other classes of microbes which are
Heterotrophs)
 Photosynthetic: important oxygen
producers in the ecosystem, contain
chlorophyll pigments
 Found in fresh and salt water
 Few are harmful

Algae

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Eukaryotic cells – unicellular
 Heterotrophic protists - ingest or
engulf food from surroundings
 Many can resist drying out/death by
going into a dormant state called a cyst
 Some are pathogens: cause malaria, amoebic
dysentery, African sleeping sickness,
toxoplasmosis

Protozoa

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Eukaryotic organisms
 Can be single-cellular (yeast) or multicellular (mushrooms and
molds)
 Cell walls – most have chitin
 Saprophytic (feeds off dead or decaying organic matter)
 Though some are parasitic and
cause disease
 Found everywhere – especially soil &
water

Fungi

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Eukaryotic cells
 Multicellular
organisms
 But many have
microscopic lifestyles,
such as dog
heartworm,
swimmer’s itch,
tapeworms

Helminths

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Very small
 500 million rhinoviruses (which cause the common cold) could fit on to the head of a pin
 Noncellular (acellular)
 No metabolism
 Genetic information is DNA or RNA
 The ultimate parasite - must use a host to reproduce
 All groups of organisms are infected by
 Many are harmful – HIV, herpes,
polio, common cold, measles,
rabies, hepatitis, Ebola, etc., etc.,
etc.

viruses

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feeds off dead or
decaying organic matter

saprophytic

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No true nucleus or nuclear membrane. include bacteria and archaea.

prokaryote

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have a true nucleus, include fungi, protozoa, and algae

eukaryote

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is derived from the
Greek taxis (“arrangement”) and nomos
(“law”)
Scientific name consists of Genus & species

Taxonomy

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why study microbiology?

Generate air we breathe (N, CO2, O2)
 Fix N for plants
 Make essential vitamins
 Primary producers in many food webs
 Some are pathogens, some are not
 Microbes are used in research and medicine

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what are the 7 classes of microbes?

Bacteria, Archaea, Algae, Protozoa, Fungi, Helminths, Viruses

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benefits of microbes

Thanks to their versatility, microbes
can be put to work in many ways:
making life-saving drugs, the
manufacture of biofuels, cleaning up
pollution, and producing/processing
food and drink.

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are all microbes alive?

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what is the binomial nomenclature system?

Each distinct species is given a scientific
name that is standard around the world in
place of common names that may differ and
cause confusion

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How do you correctly write the name of a microorganism

Scientific name consists of Genus & species
 Escherichia coli, Escherichia is the genus
and coli is the species. It is set apart from the rest of the text by
putting it in italics if typed or underlined
if handwritten.
 It must be spelled out in its entirety the
first time used. Subsequent uses can be
abbreviated with just the first letter of
the Genus and the entire species

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how and when do you abbreviate the name of a micro organism

The Genus is always capitalized and the
species is always lower case.

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This system classifies organisms into five kingdoms based on their cell type, mode of nutrition, and body organization.

5 kingdom system

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This system classifies life based on genetic and molecular evidence, particularly ribosomal RNA sequences, into three domains.

domain system

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is an early belief
that some forms of life could arise from vital
forces present in nonliving or decomposing
matter. would argue that microbes arise in the
body as a RESULT of disease state instead
of as the CAUSE of the disease state

Spontaneous genearation

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the idea that living
things can only arise from other living
things. This theory states that the microbe
invades which CAUSES the disease state

biogenesis

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How was spontaneous generation finally rejected?

Redi’s experiment refuted spontaneous generation. Three jars with a piece of meat in the bottom  One left uncovered, one corked, and the last covered with gauze

What is a spore former/bacterial endospore?

A spore former is a type of bacterium that can produce endospores, which are highly resistant, dormant structures formed in response to harsh environmental conditions. These endospores allow bacteria to survive extreme heat, radiation, desiccation, chemicals, and nutrient depletion.

who contributed to microbiology?

idk

1609 Galileo Galilei and friend Giovanni Faber perfected the first device known as a. Magnification – ability to enlarge objects  Resolving power or resolution– ability to show detail

microscope

is the enlargement of an image due to an interaction between visible light waves and the curvature of a lens. 5

magnification

____ of the final image is a product of the separate magnifying powers of the two lenses.

total magnification

is the capacity to distinguish or separate two adjacent objects. The level of detail we can see  depends on the wavelength of light that forms the image along with characteristics of the objectives  In the picture on the right, you can see image B is better resolved because the separate fingers are visible

resolution

one dye is used; reveals shape, size, and arrangement of cells

simple stain

use a primary stain and a counterstain to distinguish cell types or parts (examples: Gram stain, acid-fast stain, and endospore stain)

differential stains

reveal certain cell parts not revealed by conventional methods: capsule and flagellar stains

Structural stains

The most commonly used solidifying agent. Solid at room temperature, liquefies at boiling (100oC), does not re-solidify until it cools to 42oC * Provides framework to hold moisture and nutrients * Not digestible for most microbes

Agar

contains complex organic substances such as blood, serum, hemoglobin, or special growth factors required by fastidious microbes

enriched media

growth it restricted to a particular group or type.

selective media

permits growth of several types of microbes that show differing reactions

differential media

is a microorganism that has complex or specific nutritional and environmental requirements for growth. These organisms do not grow well on simple culture media and require enriched or specialized media to thrive.

fastidious organism

How do you calculate total magnification

objective power times ocular power

How does resolving oil help you visualize a sample when using the 100X objective

Immersion oil (resolving oil) is used with the 100X objective lens in light microscopy to improve the resolution and clarity of the sample. It works by reducing light refraction and increasing numerical aperture, which enhances image sharpness

When would you need to use an electron microscope?

Electrons have tremendous power to resolve minute structures because resolving power is a function of wavelength

How can you prepare a sample for viewing under the microscope?

Wet mounts and hanging drop mounts – allow examination of characteristics of live cells: size, motility, shape, and arrangement

What can a simple stain tell you

one dye is used; reveals shape, size, and arrangement of cells

what can a differential stain tell you?

use a primary stain and a counterstain to distinguish cell types or parts (examples: Gram stain, acid-fast stain, and endospore stain

what can a structural stain tell you?

reveal certain cell parts not revealed by conventional methods: capsule and flagellar stains

When would you use enriched agar?

Enriched agar is used when culturing fastidious microorganisms that require additional nutrients to grow. These organisms have complex nutritional needs and do not thrive on simple nutrient agar.

what can selective agar tell you?

. It helps identify and isolate particular bacterial groups based on their ability to grow under selective conditions.

what can differential agar tell you?

a type of culture medium that helps distinguish between different bacteria based on their biochemical characteristics, such as their ability to ferment sugars, produce enzymes, or break down blood cells.

What would be the benefit of using a streak plate over a pour or a spread plate

a simple and effective method used to isolate pure bacterial colonies from a mixed sample. ideal for obtaining single, well-separated colonies, which are crucial for identifying and studying specific bacterial species.

oval or spherical shaped

coccus

rod shaped

bacillus

short and plump

coccobacillus

gentle curve, like a comma

vibrio

spring-like

spirochete

helical, twist shape

spirillum

variation of cell shape and size among a species

pleomorphic

chains, cell division in 1 plane

streptococci

grape clusters, irregular division in 3 planes

staphylococci

pairs

diplo

Coating of molecules external to the cell wall, made of sugars and/or proteins

glycocalyx

Complex polysaccharide molecules arranged in a gel. Encapsulated bacteria can evade phagocytosis because the capsule covers bacterial signature (it is also slippery!)

capsules

Less tightly bound network of sugar, fat, and proteins * Usually thinner than a capsule, and “easy” to come off of cell * Protects the cell against drying, traps nutrients and binds cells together (biofilm) * Allows for adherence to rock surfaces or root hairs of plants to keep them near nutrients or oxygen (even plaque!)

slime layer

Protects the cell against drying, traps nutrients and binds cells together (

biofilm

a whip-like appendage found in certain bacteria, protozoa, and some eukaryotic cells, used primarily for motility (movement). It enables microorganisms to move through liquid environments by rotating like a propeller.

flagella

Present in gram-negative bacteria species * Fine, proteinaceous, hair-like bristles emerging from the cell surface * For adhesion to other cells and surfaces * Makes bacteria more dangerous as they can adhere to and colonize a surface instead of being washed away by mucous, urine, etc.

fimbriae

Unique type of fimbriae * Attach two cells and form a pathway for the transfer of genetic material (conjugation) * Found only in gram-negative cells * Leads to genetic variety * Problematic for us because this is one of the ways antibiotic resistance genes are spread among bacterial populations

Fili

Under the capsule and the slime layer * Composed of two basic layers: * Cell wall and cell membrane

cell envelope

Maintains characteristic shape of the cell * Prevents the cell from bursting from osmotic shock * Osmotic shock results in a rapid change in the movement of water across cell membrane. Peptidoglycan is the primary component

cell wall

Provides structural support and prevents bacterial cells from bursting due to osmotic pressure. ✔ Maintains cell shape (e.g., rod-shaped Bacillus vs. spherical Coccus). ✔ Acts as a barrier against external threats. ✔ A target for antibiotics – Penicillin and cephalosporins block peptidoglycan synthesis, killing bacteria.

peptidoglycan

Outer membrane contains _______, which are toxins

lipopolysaccharides

a group of bacteria that retain the crystal violet stain during the Gram staining procedure, appearing purple under the microscope. This classification is based on their cell wall structure, thick cell wall composed primarily of peptidoglycan and cell membrane

gram-positive

are a group of bacteria that do not retain the crystal violet stain during the Gram staining procedure and instead appear pink under a microscope. This classification is based on their cell wall structure, outer cell membrane, thin peptidoglycan layer, and cell membrane

gram negative

Have a different cell wall composition, cannot be Gram stained * Thick like G+ bacteria * 60% lipid (mycolic acid) and contains much less peptidoglycan * These lipids (fats) make the bacteria highly impermeable to most stains as well as protect them from acidic and alkali solutions * Slow growers because this relatively impermeable membrane also impedes entry of nutrients into the cell as well

acid fast bacteria

Functions in: * Providing site for energy reactions, nutrient processing, and synthesis * Passage of nutrients into the cell and discharge of wastes

cell membrane

Semi-fluid substance inside the plasma membrane * 4/5 water * 1/5 materials dissolved or suspended * Enzymes and other proteins * Carbohydrates * Lipids * Inorganic ions * Site of many chemical reactions * Found in all cells

cytoplasm

Site of protein synthesis * Found in all cells * Made of 60% ribosomal RNA and 40% protein * Consist of two subunits: large and small * Prokaryotic ribosomes differ from eukaryotic ribosomes in size and number of proteins

bacterial ribosome

is the area where the genetic material (DNA) is located. Unlike eukaryotic cells, prokaryotes do not have a membrane-bound nucleus, so their DNA is not enclosed in a separate compartment.

nuclear region

Intracellular storage bodies * Vary in size, number, and content * Bacterial cell can use them when environmental sources are depleted

granules

Sometimes flagellar movement is nonrandom movement towards a chemical

chemotaxis

Counter-clockwise rotation = straight line movement referred to as a

run

Clockwise rotation, and changes direction randomly

tumble

Flagella all over the surface

peritrichous

Flagella at both ends of cell

amphitrichous

Two or more flagella at one or both ends

lophotrichous

One polar flagellum located at one end or pole

monotrichous

Dehydrated, metabolically inactive * Spore-formation is induced following nutrient depletion * Can also be found to occur in normal conditions and may be a way that the bacteria hold troops in reserve so as not to be wiped out by sudden onset of poor conditions * Resistant to ordinary cleaning methods and boiling * Pressurized steam at 120oC (248oF) for 20-30 minutes will destroy * Some common spore forming bacteria are Bacillus species and Clostridium species

endospores

what are the characteristics of life?

living things require and transform energy, are highly organized, grow and develop, respond to stimuli, have metabolism and regulatory processes, and reproduce

what makes prokaryotes different from eukaryotes?

prokaryotes have no nucleus, no nuclear membrane, usually very small

Will prokaryotes ever evolve to be the size of an elephant? Why or why not

Prokaryotes are biologically constrained from evolving into elephant-sized organisms due to limitations in nutrient transport, energy production, structural complexity, and evolutionary adaptation. Instead, they thrive by remaining small, adapting rapidly, and colonizing extreme environments.

What are the common structural components and organelles of a prokaryotic cell?

Complex cell envelope (cell membrane, cell wall, outer membrane) * Small genome * Tightly coordinated cell parts

Prokaryotes do not have compartments like eukaryotic cells do in which to carry out chemical reactions. How do they accomplish tasks like respiration and photosynthesis

using specialized membrane structures and enzymatic processes. Prokaryotes compensate for their lack of organelles by using their plasma membrane and internal membrane structures to perform respiration and photosynthesis, making them highly adaptable to diverse environments.

How does a prokaryotic flagella move the cell?

Substances often exist in gradients: areas of higher to lower concentration * Bacteria can sense these gradients by “counting” the number of a particular substance that hit receptors on the cell surface. If the substance is an attractant, the bacterium will move towards it. * If the substance is a repellent, the bacterium will move away from it. * The bacterium cannot steer itself in one direction or another. Rather it “runs” if it is going in a favorable direction or “tumbles” if it is going in an unfavorable direction.

What is a biofilm and how does it make a bacterial cell more virulent

a structured community of bacteria that is embedded in a self-produced extracellular matrix made of polysaccharides, proteins, and DNA. This matrix allows bacteria to adhere to surfaces and protect themselves from harsh environments, including antibiotics and the immune system.

What reagents are used in the Gram Stain?

crystal violet (primary stain), Iodine (mordant), alcohol (decolorizer), safranin (counterstain).

what are the three cell wall types.

gram positive: Thick peptidoglycan layer with teichoic acids, Strong, rigid cell wall, retains crystal violet, stains purple gram negative: Thin peptidoglycan layer, outer membrane with lipopolysaccharides (LPS), Outer membrane provides resistance to some antibiotics, stains pink Acid fast: Thin peptidoglycan layer, mycolic acid (waxy lipid layer), Highly resistant to desiccation, disinfectants, and antibiotics,

Why is a special stain needed for the Acid-fast bacteria? Why doesn’t the Gram Stain work?

Acid-Fast Bacteria require a special stain because their waxy cell walls repel traditional stains. The Acid-Fast Stain is a more effective method for identifying mycobacteria and other acid-fast organisms.

How do the Mycoplasma bacteria resist osmotic shock?

have no cell walls, protected from osmotic swelling and bursting by a strengthened cell membrane that contains sterols

Biology: A Gram-negative, curved rod (vibrio-shaped) bacterium that is facultatively anaerobic and motile via a single flagellum. Disease: Causes cholera, a severe diarrheal disease due to cholera toxin, leading to dehydration and electrolyte loss. Spread through contaminated water and food.

Vibrio cholerae

Biology: An Acid-fast, rod-shaped, obligate aerobe with a waxy mycolic acid cell wall that resists staining and antibiotics. Disease: Causes tuberculosis (TB), a respiratory infection that forms granulomas in the lungs. Transmitted via airborne droplets.

Mycobacterium tuberculosis

Biology: A Gram-positive, spore-forming, obligate anaerobic bacillus that produces neurotoxins. Disease: Causes tetanus, which leads to muscle spasms and lockjaw due to the tetanospasmin toxin. Infection occurs through deep wounds contaminated with spores.

Clostridium tetani

Biology: A Gram-positive, spore-forming, anaerobic bacillus that produces toxins A and B. Disease: Causes C. difficile infection (CDI), leading to severe diarrhea and colitis, often after antibiotic use disrupts gut flora. Spread through fecal-oral transmission and contaminated surfaces.

Clostridium difficile

Biology: A Gram-negative, aerobic coccobacillus that attaches to the respiratory tract using fimbriae and toxins. Disease: Causes whooping cough (pertussis), a highly contagious respiratory infection characterized by severe coughing fits. Preventable with the DTaP vaccine.

Bordetella pertussis

Biology: A Gram-negative, facultative anaerobic coccobacillus that infects hosts via fleas. Disease: Causes plague (bubonic, septicemic, pneumonic), historically responsible for pandemics like the Black Death. Bubonic plague leads to swollen lymph nodes (buboes).

Yersinia pestis

Biology: A Gram-positive, facultative anaerobic coccus that grows in chains and produces hemolysins. Disease: Causes strep throat, scarlet fever, rheumatic fever, and necrotizing fasciitis (flesh-eating disease). Spread through respiratory droplets

Streptococcus pyogenes

Biology: A Gram-positive, facultative anaerobic coccus that forms clusters and produces coagulase and toxins. Disease: Causes skin infections, pneumonia, endocarditis, and toxic shock syndrome (TSS). Some strains, like MRSA, are antibiotic-resistant.

Staphylococcus aureus

Biology: A Gram-negative, encapsulated, aerobic diplococcus that colonizes the nasopharynx. Disease: Causes meningococcal meningitis and septicemia, leading to fever, stiff neck, and petechial rash. Spread via respiratory droplets.

Neisseria meningitidis

Biology: A Gram-negative, aerobic, motile rod with a slime biofilm and resistance to many antibiotics. Disease: Causes opportunistic infections in burn victims, cystic fibrosis patients, and immunocompromised individuals. Known for producing blue-green pigments and hospital-acquired infections.

Pseudomonas aeruginosa

Exam 1 review Flashcards

(108 cards)