Exam 1 review Flashcards
study of microorganisms or microbes
microbiology
typically thought of as
microscopic organisms (not all are
microscopic however!
microbes
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
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
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
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
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
Eukaryotic cells
Multicellular
organisms
But many have
microscopic lifestyles,
such as dog
heartworm,
swimmer’s itch,
tapeworms
Helminths
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
feeds off dead or
decaying organic matter
saprophytic
No true nucleus or nuclear membrane. include bacteria and archaea.
prokaryote
have a true nucleus, include fungi, protozoa, and algae
eukaryote
is derived from the
Greek taxis (“arrangement”) and nomos
(“law”)
Scientific name consists of Genus & species
Taxonomy
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
what are the 7 classes of microbes?
Bacteria, Archaea, Algae, Protozoa, Fungi, Helminths, Viruses
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.
are all microbes alive?
no
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
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
how and when do you abbreviate the name of a micro organism
The Genus is always capitalized and the
species is always lower case.
This system classifies organisms into five kingdoms based on their cell type, mode of nutrition, and body organization.
5 kingdom system
This system classifies life based on genetic and molecular evidence, particularly ribosomal RNA sequences, into three domains.
domain system
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
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
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
