Microbiology Exam 3 Week 7

studied byStudied by 2 people
get a hint

what are prokaryotes

1 / 101

encourage image

There's no tags or description

Looks like no one added any tags here yet for you.

102 Terms


what are prokaryotes

made of prokaryotic cells

all unicellular

New cards

what defines prokaryotic cells

no nucleus no membrane bound organelles

New cards

how do prokaryotes reproduce

binary fission

New cards

what are the taxonomy of prokaryotes

domain: Bacteria and Archaea

kingdom: Bacteria and Archaea

New cards

what is a species

a group of organisms that can interbreed and have fertile offspring

New cards

why does the original species definition not work for prokaryotes?

prokaryotes breed by binary fission-asexually

New cards

how do we classify prokaryotes

based on similarities in appearance physiology and genes

New cards

what are subspecies strain or type

some species but have differing characteristics

New cards

what is a serotype

same species but stimulate a different immune response

New cards

what is a cell envelope

outer covering of cell

surrounds the cell

New cards

what are parts of prokaryotes

structures inside and outside of cell

New cards

what are the virulence factors for prokaryotes

increase ability to cause disease

secretion system


outer membrane

acid fast



bacterial endospores

New cards

what are the layers of the cell membrane

cell membrane and cell wall (peptidoglycan (PTG)

and outer membrane

New cards

what is the cell membrane

also called plasma membrane or cytoplasmic membrane

just outside the cytoplasm

denies the boundary

all cells have this

New cards

what is the cell membrane made of

two opposing leaflets of phospholipids (phospholipid bilayer)

is embedded with numerous proteins

New cards

what does a phospholipid bilayer contain

a hydrophilic head and hydrophobic tail

New cards

what is a cell wall

surrounds the cell membrane

New cards

what is the cell wall made of

peptidoglycan in most bacteria ~90%

outer membrane in some bacteria ~40%

New cards

what does the cell membrane distinguish

gram positive and gram negative

New cards

what does gram positive show

plasma membrane

large peptidoglycan area


New cards

what does gram negative show

plasma membrane


small peptidoglycan area

have an outer membrane

New cards

what is peptidoglycan (PTG)

chemical found only in bacteria

gives cell structural rigidity and shape

major target of antibodies

very important for target antibiotics

New cards

what is peptidoglycan made of

long sugar chains (glycan) connected by protein chains (peptide)

New cards

how are glycan chains held together

by peptide bridge (gives structure)

New cards

what is the outer membrane of PTGwhat

similar to cell membrane

outer leaflet of bilayer is made of lipopolysaccharides (LPS)

New cards

what can large amounts of LPS in the bloodstream mean

can result in death

New cards

what is LPS also called


New cards

what is LPS made of

polysaccharide that functions as a receptor

specific sequence helps us identify serotypes (o antigens)

ex) e coli

New cards

what is lipid a of LPS

the toxic part

New cards

what is the core of LPS


New cards

what is the outer membrane in LPS

it protects bacteria from host immune system

very impermeable (prevents almost anything from going through)

New cards

how do small molecules cross outer membrane in LPS

facilitated diffusion

other substances may require secretion systems

New cards

what is the secretion system

protein complexes embedded within membranes to transport virulence factors (such as toxins) out of the cell

different types based on structure and function (can travel across one membrane or many)

New cards

who is Hands Christian Gram

found that different types of cells would retain the dye differently in his staining method

New cards

what is a gram stain

divide bacteria into two major categories based on the fundamental differences in cell walls

New cards

what is the key test in identification of bacterial species

purple- gram positive

pink-gram negative

New cards

what is the cell membrane of a gram positive envelope

small periplasmic space between the membrane and PTG

New cards

what is the peptidoglycan on a gram positive envelope

thick, many sheets (30-50)

permeable to numerous substances

has teichoic acid/lipoteichoic acid

New cards

what do teichoic acid/lipoteichoic acid do

link envelope together

New cards

what is the gram negative envelope summary

cell membrane

periplasmic space- thin layer of PTG (2-5)

outer membrane- outer leaflet made of LPS not permeable

New cards

what is a primary stain

crystal violet (basic)

New cards

what is a mordant stain

iodine (complexes)

New cards

what is decolorization/destaining

ace tone/alcohol/water

New cards

gram positive stains


crystal violet-blue

iodine treatment-purple

decolorization- purple

counter stain w/ safranin-purple

New cards

gram negative stains


Crystal violet-blue

iodine treatment-purple


counter stain w/ safranin- pink

New cards

what are cell wall expections

some bacteria have extra layers to their cell wall

acid fast bacteria have waxy lipid layer attached to cell wall made of mycolicacid

New cards

acid fast bacteria

technically gram positive cells but do not retain the gram stain

resists treatments with chemicals and dyes

New cards

what is acid fast stain- differential

use heat on organisms that do not readily take up dyes

New cards

what do some bacteria naturally lack

cell wall

New cards

what causes walking pneumonia mild pneumonia?


New cards

what are structures outside of the cell

glycocalyx ( extracellular matrix, simple layer, capsule)

appendages (flagella, frimbrae, pili)

New cards

what is glycocalyx

viscous and gelatinous

made of carbohydrates and/ or protein

protect the cell from drying out and/ or host immune system

sometimes helps the cell adhere to the environment

differ among bacteria in thickness/organization and chemical composition

New cards

what are the two types of glycocalyx

slime layer (s layer)


New cards

what is the slime layer

loose Shiel that protects some bacteria from loss of water and nutrients

(diffuse and irregular)

New cards

what is a capsule

count more tightly to the cell and is denser and thicker

is a virulence factor

protect the bacteria against immune system

important in the formation of biofilms

New cards

what are biofilms

mixed communities of different species of microbes

free living planktonic bacteria attach to a surface

other microbes attach to the pioneer and begin secreting capsule that covers entire colony

parts can break away and infect other places

removal is extremely difficult

resists immune response, heat, chemical, mechanical remover

New cards

where are biofilms naturally found in the body

dental plaque

New cards

where can biofilms be found

in sewage treatment systems; can clog pipes

New cards

what are biofilms involved in

70% of infections of catheters, intrauterine devices, pacemakers, heart valves, contact lenses, etc

New cards

what is a capsule stain

a gelatinous covering that do not accept most dyes

consist of two dyes ( acidic and basic)

appears as a halo around the cell

New cards

what step is missing compared to a normal smear and stain?why?

we never fix (put under heat)

can’t get hot so capsule will stain

New cards

what are appendages

some bacteria have external appendages

not essential of life but aid in survival in certain environments

3 types




New cards

what is flagella

filamentous appendages external of the cell

responsible for motility (movement)

use propeller like movements to push bacteria

three basic parts

filament-extend to exterior; made of proteins called flagellin; also called H antigen(distinguish among serotypes (ex. e coli))

hook- connects filament to basal body

basal body-anchors flagellum into cell wall

New cards

what is monotrichous

single flagellum at one pole

New cards

what is lophotrikhous

tuft of flagella at one end

New cards

what is amphitrichous

flagella at both poles

New cards

what is peritrichous

flagella all over

New cards

what is chemotaxis

bacteria sense chemicals and move accordingly

nutrients may attract, toxins may repel

bacterial movement is series of Rons (straight line) and tumbles (change in direction)

New cards

what is aerotaxis

movement bc of oxygen

New cards

what is magnetoraxis

movement bc of magnetic field

New cards

what is thermotaxis

movement because of temperature

New cards

what is phototaxis

movement bc of light

New cards

what can be used as a diagnostic tool

motility and the presence of flagella

New cards

how do you observe motility

wet mount

movement in agar-agar stab

New cards

what is a flagella stain

coats the flagella to thicken appearance, making them visible under a light microscope

New cards

what are axial filaments

also called endoflagella

found in spirochetes

wrapped around entire cell

rotation causes cell to move like a corkskrew

New cards

what are other appendages

frimbriae- velcro; small bristle like protein fibers; tend to stick to each other and to surfaces

sex pili- elongated rigid tubular structures; made of protein pillion; used in conjugation

New cards

what are the internal structures of bacteria suspended in

cytosol-gelatinous solution;70-80% water; site for most biochemical. and synthetic activities

New cards

what is the entire interior of the cell referred as


New cards

prokaryotic dna

usually circular

main chromosome is required and has all the genes needed for life

the main chromosome is located in a dense gel like region-nucleoid

replicants during binary fission

nonessential and optional but often confer protective traits such as drug resistance or the production of toxins and enzymes

few to several hundred genes (~5% size of the chromosome)

independently replicating

New cards

what are plasmids

prokaryotes small circular pieces of DNA that exist independently of the chromosome

New cards

what is vertical gene transfer

plasmids are passed down to the next generation of cells

this is a normal part of cell division

<p>plasmids are passed down to the next generation of cells</p><p>this is a normal part of cell division </p>
New cards

what is horizontal gene transfer

plasmids are transferred to existing cells in the same generation

3 ways of occurring-

transformation transduction conjugation

New cards

steps for conjugation-sex pili

1)donor cell attaches to a recipient cell with its pilus. the pilus draws the cells together (tube that connects)

2)the cells contact one another

3)one strand of plasmid DNA transfers to the recipient

4)the recipient synthesizes a complementary strand to become an f+ cell; the donor synthesizes a complementary strand restoring its complete plasmid

New cards

what are ribosomes

responsible for translation (protein synthesis)

made of RNA and protein 50/50

prokaryotic ribosomes are 70s

-small subunit 30s

-large subunit 50s

-suedburg: how things sink or rise

New cards

what are inclusion bodies

vary in size number and content

-gas vacuoles maintain buoyancy

-storage sites for nutrients during periods of abundance that serve as storehouse when nutrients become depleted

-sulfur, lipids, polysaccharides

New cards

what is prokaryotic cytoskeleton

inferior protein framework

contributes to cell shape and likely involved in cell division

similar to the cytoskeletal filaments of eukaryotes

New cards

what are bacterial endospores

found virtually anywhere


-may remain dormant for 100 years or longer

-extremely resistant to heat, desiccation, chemicals, UV light, and boiling water

produced only 3 genera

some diseases are related to the persistence and resistance of their spores

-bacillus anthraces: anthrax

-clostridioides difficile: pseudomembranous colitis (c. diff)

-clostridium tentani: tetanus (lockjaw)

c. perfringens: gas exchange

c. botulinum: botulism

New cards

what is the medical significance of endospores

are constant with intruders where sterility and cleanliness are important

-resist ordinary cleaning methods: boiling water soaps and disinfectant

-frequently contaminate cultures and media

-hospitals must protect against endospores in wounds

-destruction of endospores is important in the food canning industry

New cards

what are the steps for endospore formation

  1. vegetative cell

    1. metabolically active and growing

    2. conditions are favorable for growth

  2. sporulation

    1. process of vegetative cell converting to an endospore

    2. caused by unfavorable conditions

    3. process takes about 8 hours

  3. free endospore

    1. hardiest of all life forms

    2. many layers protect DNA

    3. excludes molecules and maintains dehydrated state protects from heat

  4. germination

    1. spore turns back into vegetative cell

    2. occurs in the presence of warmth water and a specific germination agent (ex: amino acid or salt)

    3. quite rapid (1.5 hours)

New cards

what is a endospore stain

spores are resistant to staining

use heat to force color inside

New cards

what is archaea

the most primitive of all life forms

most closely related to cells that originated 4 billion years ago

New cards

what are extremophiles

live in habitats that are similar to the extremes found anciently- heat, salt, acid, pH, pressure, and atmosphere

New cards

what are methanogens

convert carbon dioxide and hydrogen gas into methane

-common in habitats of anaerobic swamp mud, bottom sediments of lakes and oceans and the digestive systems of animals

New cards

what are halophiles

live in 36% NaCl that would destroy most cells

-exist in inland seas, salt lakes, salt mines, and in salted fish

New cards

what are hyperthermophiles

grow at very high temperature

-live in volcanic waters and soils and submarine vents

-often salt and acid tolerant as well as heat tolerant

New cards

what did archaea used to be considered

a type of bacteria

-early bacteriologist classified according to shape arrangement growth characteristics and habitat

New cards

what is evolutionary relatedness

the most accurately determined through comparison of nitrogen bases in ribosomal RNA

-tend to remain stable over long periods

-any major differences in the signature sequence indicates distance in ancestry

New cards

what domain are archaea more related to


  • share ribosomal rna sequences not found in bacteria

New cards

what is the difference of archaea from other cell types

unique method of DNA compaction

unique membrane lipids cell wall composition and pillion proteins

New cards

Explore top notes

note Note
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 117681 people
Updated ... ago
4.9 Stars(594)
note Note
studied byStudied by 19 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 1 person
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 7 people
Updated ... ago
5.0 Stars(3)
note Note
studied byStudied by 10 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 15 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 36 people
Updated ... ago
5.0 Stars(2)

Explore top flashcards

flashcards Flashcard103 terms
studied byStudied by 30 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard42 terms
studied byStudied by 16 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard54 terms
studied byStudied by 10 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard40 terms
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard49 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard93 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard69 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard33 terms
studied byStudied by 3 people
Updated ... ago
5.0 Stars(1)