microbiology exam 1

agar

a substance used to make culture media solid so microoragnisms can grow on a solid surface

amphitrichous

a single flagellum present at both ends (poles) of a microbial cell

archaea

• prokaryotic single-celled organisms

• non-pathogens (does not cause disease)

• most found in extreme/harsh environments

aseptic technique

methods of handling microbial cultures in a way that prevents infection of yourself and others

• also prevents contamination

bacterial endospore

produced in times when nutrients are low to help bacteria survive hostile/harsh conditions

biogenesis

living things originate from other living things

• ex: A bacterium divides and produces two new bacteria.

bacterial endospores

tough protective structures that some bacteria make to survive harsh conditions.

budding

when a virus leaves a cell by pushing through the cell membrane and taking part of the membrane with it.

capsid

made of proteins called capsomers

• shell that surrounds and protects a virus’s genetic material (DNA or RNA)

• auto assemble

what are the 3 shapes of capsids

• Icosahedron: symmetric 3-D soccer ball or cubed shape

• Helical: “bracelet”

• Complex: “space craft:

capsomere

a subunit of the virus capsid shaped as a triangle or disc

• one individual protein piece that makes up a viral capsid.

Think of it like LEGO:

🧩 Capsomeres = individual LEGO pieces

🦠 Capsid = the whole LEGO structure/shell

cilia

short, hair-like structures that help a cell move or move substances along the cell surface.

• some cells have several thousand

• found only in protozoa and certain animal cells

• BACTERIA DO NOT HAVE CILIA

complex media

contains at least one component that is not chemically definable (you don't know the exact chemical makeup of at least one ingredient)

• agar

what are 3 properties of an effective microscope

• magnification

• resolution

• contrast

contrast

the difference between the specimen and the background

• High contrast → specimen is easier to see.

• Low contrast → specimen blends into the background.

Creutzfeldt-Jacob disease

a rare, fatal brain disease caused by prions

• HUMANS GET THIS (from cows?)

decomposers

microorganisms that break down dead organisms and waste into simpler substances

• bacteria and fungi

differential stain

a technique that utilizes two dyes to distinguish between different microbial groups by color

• ex: gram stain

  • 🟣 Gram-positive bacteria = purple

  • 🩷 Gram-negative bacteria = pink

dimorphic

when some pathogens alter their growth form from mold to yeast because of rising temperature (can exist in 2 forms)

• mold→ yeast when temperature rises

Endosymbiont

an organism that lives inside another organism and benefits from the relationship.

• ex: The bacteria that eventually became mitochondria and chloroplasts were once endosymbionts.

enriched media

a growth medium with extra nutrients added to help fastidious bacteria (picky, hard to grow, need extra to grow) grow

• ex: blood agar, Thayer-martin medium (chocolate agar)

Enterobius vermicularis

pinworm, a parasitic worm that infects the human intestines

• Important symptom: itching around the anus, especially at night.

envelope

found in some viruses, but not all

• not found in naked nucleocapsid virus

• formed by budding

• derived from the host cell membrane but altered

the outer membrane surrounding some viruses.

It comes from the host cell’s membrane when the virus leaves the cell by budding.

fastidious

requires special nutrient or environment conditions to grow

fimbria

short appendages (something attached to or sticking out from a cell/body) that help bacteria attach to host cells/surfaces

• does not help them move (locomotion), though

  • ex: E. coli uses fimbriae to attach to cells lining the urinary tract, which can help it cause a UTI.

flagella

a structure that is used to propel(moves) the microorganism through a fluid environment

• “like a motor, spins like a propellor”

what are the 2 major groups of appendages (structures that stick out of a cell)

• flagella and axial filaments: provide motility

• fimbriae and pili: provide attachment points or channels

General Purpose Media

material used to grow many different types of microbes

• ex: nutrient agar

hemolysis

when bacteria break down red blood cells

• Beta (β) hemolysis → complete breakdown → clear area around bacteria

• Alpha (α) hemolysis → partial breakdown → greenish area

• Gamma (γ) hemolysis → no breakdown → no change

inclusion bodies

membrane bound, storage compartments for nutrients in bacterial cells

interferon

naturally occurring human cell product

• a protein made by cells that helps protect the body from viruses

• interferes with viral replication

  • used with some success in preventing and treating viral infections

isolated streak

Streaking bacteria across an agar plate to separate them into individual colonies.

Koch’s Postulates

a set of rules for establishing/proving that a specific organism causes a specific disease

• 1. the same pathogen must be present in every

case of the disease.

• 2. The pathogen must be isolated from the diseased host and grown in pure culture.

• 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.

• 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

• Find it → The same pathogen is found in every sick person.

• Isolate it → Take the pathogen out and grow it by itself.

• Test it → Put it into a healthy animal → it causes the same disease.

• Find it again → Take the pathogen from the sick animal and confirm it’s the same pathogen.

Lipopolysaccharide (LPS), endotoxin, Outer membrane, porin proteins

all components only found in gram negative

• endotoxin (part of LPS, in outermembrane)- causes fever in infections

• porin proteins (proteins in outer membrane)- form tiny channel to let small molecules enter and allow some waste to leave

lophotrichous

small bunches or tufts of flagella at one or both poles

lysogeny

viral DNA stays inside the host without making new viruses.

magnification

how much larger an object appears when you look at it through a microscope

• 10× magnification → the object appears 10 times larger than it looks to your naked eye.

• 40× magnification → appears 40 times larger.

Monotrichous

a microorganism that has one flagellum at one end

where is mycolic acid found

in the cell walls of mycobacterium

what is mycolic acid

a thick, waxy, very long chain fatty acid (Lipids)

what does mycolic acid contribute to

pathogenicity of organisms (helps organisms cause disease)

acid fast used to diagnose tuberculosis and leprosy

negative stain

a staining technique that stains the background dark gray or black and the cell clear and colorless

nucleoid

• contains genetic material (dna, prokaryotic cells)

• no nuclear membrane, no nucleus

• single circular chromosome (prokaryotic)

• the DNA is in close proximity to the cytoplasm and ribosomes

nucleolus

part of the nucleus where rRNA is made and ribosomes are assembled

oncovirus

A naturally occurring type of gene that when activated can transform a normal cell into a cancer cell.

• poses genes that directly cause uncontrolled growth of cells

  • a virus that can cause cancer by infecting cells and changing how they grow and divide.

pathogens

any microorganism that causes disease

Peptidoglycan

a network of polysaccharide chains cross linked by short peptides that forms the rigid part of the bacterial cell walls

• rigid bacterial cell wall made of sugar chains cross-linked by short peptides.

• provides strength

• contains alternating glycans G and M, bound together in long strands

  • NAM and NAG alternate

Peritrichous

having flagella over the entire cell

phagocyte

a class of white blood cells that can engulf and destroy foreign cells and particles

positive stain

cells are colored by dye while the background is not stained, generally white

• ex: Bacteria appear purple or blue, while the background stays mostly clear.

Presumptive diagnosis

a likely diagnosis based on initial signs, symptoms, and tests, but it is not confirmed yet.

prion

• is a misfolded protein that can induce normal proteins to misfold, leading to fatal neurodegenerative diseases in humans and animals

• animal pathogens

• smaller and simpler than viruses

• no nucleic acid→ RNA or DNA

• Spongiform encephalopathy

  • diseases where the brain becomes damaged and develops a sponge-like appearance.

    • ex:

      • Mad Cow Disease → affects cattle; caused by prions.

        Creutzfeldt-Jakob Disease (CJD) → prion disease in humans

prokaryotes

a cell that does not have a nucleus or membrane bound organelles

• ex: bacteria and archea

Prophage?

phage DNA that hides inside a bacterium’s chromosome instead of making new viruses right away.

• It can later become active and make new viruses, which can kill the bacterial cell.

provirus

viral DNA that is inserted into a host cell’s DNA

pure culture

a container growing a single species of microbe whose identity is known

• culture that contains only one type of microorganism

• ex: a container containing only e. coli is a pure culture

resolution

the capacity of a microscope lens system to accurately distinguish between two seperate entities that lie close to each other

• the ability to tell two close objects apart

saprobe

a microprobe that decomposes organic remains from dead organisms

• ex: mushrooms

  • gets nutrients by breaking down dead plants and animals.

sex pilus

a structure that helps bacteria transfer DNA to another bacterium

• conjugation

• DNA “bridge” between bacteria.

simple stain

a staining technique that uses one dye to color cells, making them easier to see.

spike

proteins sticking out from the surface of a virus that are essential for the attachment of viruses to the next host cell

spontaneous generation

early belief that life rapidly appears from non-living things

• ex: People once believed flies could appear from rotting meat

Sterols

lipids that help stabilize cell membranes

• ex: mycoplasmas- they lack a cell wall, so their membrane is stabilized by sterols

streak plate

a technique used to isolate pure bacterial colonies by progressively diluting a sample across the surface of an agar plate. It creates areas with fewer cells so individual colonies can grow separately, allowing identification and purification of microorganisms.

• a technique used to separate bacteria on an agar plate so individual colonies can grow.

• Purpose: To get pure, isolated bacterial colonies for identification.

swan necked flask

• a flask with a long, curved neck that allows air to enter but prevents microorganisms from reaching the broth.

  • Louis Pasteur used swan neck flasks to disprove the idea of spontaneous generation

• 🧪 Pasteur boiled the broth → killed the bacteria already inside.

• 🦢 The swan neck let air in, but trapped dust and bacteria in the curved neck.

• ⏰ The broth stayed free of bacteria.

• When the neck was taken off, bacteria grew

disproved spontaneous generation.

Synthetic (Defined) Media

a growth medium where we know EXACTLY what chemicals are in it and how much of each.

temperate virus

a type of virus that can either kill their host immediately or hide inside it without causing harm, waiting to reactivate later

ubiquitous

found everywhere

• ex: bacteria are found everywhere

Viral host range

the types of cells or organisms that a virus can infect

• example:

  • A virus might infect only humans.

  • Another virus might infect humans and certain animals.

  • Some viruses can infect only certain types of cells in the body.

what did joseph lister do

British surgeon

he applied the germ theory to the treatment and prevention of disease

used carbonic acid (phenol) to clean hands, wounds and operating rooms

introduced antiseptic surgery

• number of post-op infections were reduced

• initiated the use of aseptic techniques to surgery

what did Antonie van Leeuwenhoek do

Dutch fabric merchant

first person to accurately describe living microbes

used a simple microscope

termed microbes “animalcules”

what did Robert Hooke do

English naturalist and architect

• compound microscope

• may have been the first to see microorganisms

• coined the word “cell”

what did Francesco Redi do

Italian natural philosopher

• uncovered dishes of meat filled with maggots

  • covered dishes of meat attracted flies, but maggots formed on the gauze not on the meat

• disproved spontaneous generation of maggots

what did Louis Pasteur do

French microbiologist (father of microbiology)

used swan necked flasks

• disproved spontaneous generation

Advent of Pasteurization

• discovered that wine was going sour because of harmful microbes. He heated the wine to kill them.

Germ theory of disease

• He then realized that if microbes can infect wine, they can also infect people, helping lead to the germ theory of disease.

what did Robert Koch do

• German microbiologist

• worked on anthrax, tuberculosis, and cholera

• used pure cultures (initiated the use of agar)

• further developed the germ theory of disease

• described several postulated for proving the causative agent for disease

  • KOCHS POSTULATES

what did Ignaz Semmelweis do

Hungarian Physician

doctor who discovered that handwashing prevents infections.

• “Savior of mothers”

• hand disinfection prevented transfer of infections

• hand washing by doctors prior to attending maternity patients increase mortality

what did John Tyndall do

English physicist

studied microbes in hay infusions.

• Discovered heat-resistant microbes (microbes that survive heating).

• Used discontinuous heating (heating, cooling, then reheating) to sterilize materials.

what did Oliver Wendell Holmes do

American physician

• observed spread of puerperal fever by health care providers

• published findings that supported the importance of handwashing and cleanliness.

acellular vs cellular

acellular

• not made of cells

• cannot reproduce on their own

  • ex:

    • viruses

cellular

• made of cells

• carry out life processes themselves

  • cellular prokaryotes

    • bacteria and archaea

  • cellular eukaryotes

    • fungi, algae, protozoa, and helminths

what are the different kinds of eukaryotes

fungi, algae, protozoa, helminths

what are the 2 major categories of Protists

algae and protozoa

describe fungi

unicellular/multicellular

• has a cell wall (chitin)

  • ex:

    • molds (multicellular, reproduce by producing conidia)

    • yeasts (unicellular, reproduce by budding)

• sexual and asexual reproduction

describe algae

unicellular/multicellular

• has a cell wall (cellulose)

• protist

• usually don’t cause human infection

• usually make their own food through photosynthesis.

describe protozoa

• eukaryote

• Always unicellular

• NO cell wall

• grouped by locomotion (flagella or cilia)

describe helminths

• multicellular

• no cell wall

• two main groups

  • flat worms

  • round worms

compare and contrast gram positive and gram negative

gram positive

• thick peptidoglycan cell well

• During Gram staining, crystal violet (CV) + iodine (I) form a CV-I complex

• The thick peptidoglycan traps the CV-I complex

• Alcohol cannot remove it

• STAYS PURPLE

• contains

  • teichoic acid and lipoteichoic acid

gram negative

• thing peptidoglycan cell wall

• unable to retain CV-I complex during decoloring alcohol wash bc of thin cell wall

• safranin stains them PINK/RED

• has OUTER MEMBRANE (harder to kill)

  • contains

    • lippo proteins-help connect the outer membrane to the peptidoglycan layer

    • lipoplysaccrhices- endotoxin

    • porin proteins- allow certain small molecules to enter

compare and contrast eukaryotes and prokaryotes

eukaryotes

• have a nucleus

• DNA is inside the nucleus

• Usually linear DNA

• Have membrane-bound organelles

• Can be unicellular or multicellular

• Usually larger

• Examples: Fungi, protists, plants, and animals

• Have cell membrane, cytoplasm, ribosomes, and DNA

prokaryotes

• No nucleus

• DNA is in the nucleoid

• Usually circular DNA

• No membrane-bound organelles

• Usually unicellular

• Usually smaller

• Examples: Bacteria and Archaea

• Have cell membrane, cytoplasm, ribosomes, and DNA

what are examples of prion diseases

Spongiform encephalopathy (a disease where the brain develops sponge-like holes because of abnormal prion proteins)

• mad cow disease- cows

• Creutzfeldt- Jakob disease- humans

mycobacteria

has a cell wall

• contains mycolic acid found in its cell walls

mycoplasma

lack a cell wall

• membrane is stabilized by sterols and is resistant to lysis (less likely to burst/open and break apart)

cellular morphology

the shape and arrangement of cells

coccus

round/spherical

bacillus/rod

rod shaped

curved

bacteria that have a bent or curved shape

staphlyo

cells arranged in clusters

strepto

cells arranged in chains

sarcina

Cubical packet of 8, 16, or more spherical cells

diplo

cells arranged in pairs (2)

tetrad

four cells arranged together

vibrio

comma shaped, curved bacteria