Exam one Microbiology – Flashcards

Unlock all answers in this set

Unlock answers
question
Hooke
answer
- constructed the first compound microscope and published the first illustration observed through a microscope. Coined the term "cell".
question
Leeuwenhoek
answer
designed powerful microscoped allowing him to search for microbes in unexpected habitats
question
Magnification vs. resolution
answer

-magnification- an increase i nthe apparent size of an image to resolve smaller separations between objects

 

-resolution- the smallest distance by which two objects can be separated and still be distinguished

question
Bright Fields vs. Dark Field Microscopy
answer

- Bright field: generates a dark image of an object over a light background. Shows that light does not pass through. (you have to use a stain)

 

- Dark Field: Enables microscopes to be visualized as halos of bright light agianst darkness. (small images are visable)

question
Why would i use a fluorescence Microscope?
answer
to observe the resolution of small structures
question
TEM vs SEM
answer

-transmission electron microscopy- electrons pass through the specimen, and reveals internal structures.

 

- scanning electron microscopy- electrons scan the specimen surface, reveals external features in 3D

question
Cell membrane
answer
  • encloses the cytoplasm
  • defines existence of the cell
  • consists of phospholipids and proteins
  • structural support
  • detection of environmental signals
  • secretions of virulence factors and communication signals
  • ion transport and energy storage
  • semi permeable membrane
question
cell wall
answer
  • covers the cell membrane
  • confers shape and rigidity to the cells, helps withstand turgor pressure
  • the bacterial cell awll is called the sacculus, consists of single interlinked molecules.
question
Nucleoid
answer
  • non membrane bound area of the cytoplasm that contains the chromosome in the form of looped coils
  • prokaryotes have a nucleoid region that extends throughout the cytoplasm
question
selective transport
answer
  • essential for survival
  • precents a cell from coming to equilibrium
  • small uncharged molecules permeate the membrane by diffusion
  • water tends to diffuse across hte membrane in a process called osmosis
question
passive transport
answer
  • molecules move along their concentration gradient
question
active transport
answer
  • molecules move against their concentration gradient- requires energy (it takes energy to make energy)
question
chemotaxis
answer
  • the movement of a bacterium in response to chemical gradients
  • attractants cause counter clock wise rotations

- flagella bundle together, push cell forward, "swim"

  • repellents cause clockwise rotations

-flagellar bundle fall apart, tumble (bacterium briefly stops then changes direction

  • the runs and tumbles cause a "random walk"
  • receptors detect attractant concentrations (sugar, amino acids)
  • attractant concentration increases and prolongs runs

-termed a "biased walk"

-causes net movement of bacteria toward attractants (or away from repellents)

question
structure of peptidoglycan
answer
  • repeating disacharaide that is crosslinked with an amino acid bridge through NAM
  • repeating units of NAM and NAG crosslinked with a pepto animo acid bridge
  • consists of long polymers two disaccharides called NAG and NAM bound to a peptide of 4-6 amino acids (SUGAR)
  • two parts, 1) Peptide 2) Sugar- the back bone
  • the peptides can form crosslinks connecting the parallel glycan strands

 

question
gram positive
answer
  • bacteria with a thick cell wall
  • cell envelope- everything outside the plasma membrane
  • S-layer (not all species)- made of proteins
  • thick cell wall- amino acid cross-links in peptidoglycan, 20-30 layers of peptidoglycan
  • plasma membrane
question
gram positive
answer
- bacteria with a thick cell wall
question
D vs L amino acids... which is unique to gram positive
answer
  • D- does not fit through ribosome
  • L- fits through ribosome
question
where is teichoic acid and what is it's purpose?
answer
  • teichoic acids- provide strength (unique to gram positive)
  • located in the cell envelope
question
what is a capsule?
answer
  • a capsule is not in every species it is made of polysaccharides (most pathogens have capsules)
  • located in the cell envelope
question
why do i care that mycobacteria have mycolic acid?
answer
  • mycobacteria- complex cell
  • excludes antibiotics and lots of nutrients-- results in malnutrition and slow growth
  • mycolic acid- unusual membrane lipids
question
What is in the outer membrane of gram negative bacteria?
answer
  • a thin peptidoglycan layer consisting of one or two sheets covered by an outer membrane which confers defensive abilties
question
3 parts of  LPS and which part s toxic and which part confers serotype specificity?
answer
  • 1. O polysaccharide- confers serotype specificity
  • 2. core polysaccharide
  • 3. lipid A - TOXIC0 overheating unit
question
Gram stain... which bacteria are purple vs pink and why
answer

gram positive: purple, becuase iodine complex wiht crytal violet increases stain retention (thick cell wall)

 

gram negative: stain is removed when washed with ethanol becuase of their thin cell wall. (turns pink)

question
Purpose of flagellum how does it work in general?
answer
  • a spiral filament of pretein monomers called flagellin
  • the filament is rotated by a motor driven by the proton motive force (basil body and hook curves into flagella)
  • assists prokaryotes in movement
question
Facilitate Transport vs active transport
answer
  • facilitate trasnport (passive transport)- helps solutes move across a membrane from a region of high concentration to one of lower concentrations.

- it does not require energy and cannot move a molecule against its gradient

  • Active Transport- requires energy. movement of molecules against its gradient
question
Coupled transport- Symport vs. Antiport
answer
  • coupled transport systems are those in whcih energy released by moving a driving ion down its gradient is used to move a solute up its gradient
  • symport- two molecules travel in the same directon
  • antiport- two molecules move in the direction opposite to the driving ion
question
siderophore
answer
  • specialized molecules secreted to bind ferric ion and transport it into the cell.
  • the ion is released into the cytoplasm and reduced to the more useful ferrous form
question

group translocation

 

answer
  • a process that uses energy to chemicall alter the substrate during its transport
  • PTS (phosphotransferase system (present in all bacteria)).

-unses energy from phospheonolypyruvate (PEP) to attatch a phosphate to specific sugars

- the system has a modular design that accommodates different substrates

question
Spontaneous generation- how/who disproved the theory. What was the experiment? What was the potential flaw in the experiment?
answer
  • The theory that living creates could arise without parents
  • francesco Redi- showed that maggots in decaying meat were offspring of lies
  • lazaro spallanzani- showede that a sealed flask of meat broth sterilized by boiling failed to grow microbes
  • louis pasteur- discovered the microbial basis of fermentation

-devised "swan neck" flask

-showed that, after boiling, the contents reain free of microbial growth despite access to air

- his flaw was that the organisms that grew in pasteurs flask were spires that were not killed by boiling

question
selective vs differential media
answer
  • selective- favor the growht of one organism over another (there is either growth or not growth)
  • Differential- expoit differences between two species that grow equall well
question
Growth curve and what occurs in each phase
answer
  • Growth curve- expontential growth does not last forever.
  • 1. lag- bacteria are preparing their cell machinery for growth
  • 2. log
  • 3. stationary phase- where secondary metabolites are aborbed
  • 4. Death phase- everything is dying
question
Biofilm... why do i care?
answer
  • Biofilms- specialized surface-attached communities formed by bacteria
  • 1. attachement monolayer
  • 2. micocolonies
  • 3. exopolysacharides production
  • 4. mature biofilm
  • 5. dissolution and dispersal
  • antibiotics cannot get through the biofilm- provides a unit of safety
question
What is an endospore? When does it appear? Name one genus of bacteria that makes spores. Do spores grow? Why do I care? How do i get rid of them? Why do i care?
answer
  • endospore- only gram positive makes spores- (bacillus)

- heat resistant

  • appear during starvation- an asymmetrical cell division process that produces a forespore and ultimately an endospore
  • THEY DO NOT GROW
  • Metabolically inactive so you have to kill them wiht a combination of high pressure and temperature (steam autoclave). They have everything to create a new bacteria but they are METABOLICALLY INACTIVE
question
Eutrophication
answer
  • the sudden infusion of large quantities of a formerly limiting nutrient
  • can lead to a bloom of microbes, which threaten the existence of competing species.
question
-phile vs. -phobe
answer

-phile- like

-phobe- dislike

tolerant- tolerate

question
Extremophiles, psychrophiles, vs mesophiles vs thermophiles. What is the main cellular structure that changes between the optimal growth temps of these. Why can psychrophiles survive at thermophile temps?
answer
  • psychrophiles 0-4 C
  • mesophiles- 15-45 C
  • thermophiles 40-80C
  • hyperthermophiles 65-121C
  • extremophiles- organims ability to survive in a ecological niche outside the normal growth conditons
  • becuase they are tolerant- they can only live in an environment between 0-20C
question
does internal pH change for alkaliphiles like the internal temp of a thermophile? Why? How do bacteria mangae the extreme pHs?
answer
  • enzymes activites exhibit iptima, minima and maxima with regard to pH
  • bacteria regulate internal pH range
  • wake acids can pass through membranes

-disrupt cell pH homeostasis and thus kill the cell

- IF YOU DISRUPT THE INTERNET pH YOU WILL KILL THE CELL

  • the internal pH does not change if it does the cell will die
  • under extreme conditoons the cell can use the N+/H+ antiporter to bring protons into the cell in exchange for expelling Na+.
question
classification of microbial responses to oxygen
answer
  • strict aerobes- can only grow in oxygen
  • microaerophiles- grow only at lower O2 levels
  • strict anaerobes- die in the least bit of O2
  • facultative anaeroves- can live without without oxygen
  • aerotolerant anaeroves- grow in oxygen while retaining a fermentation-based metabolism
question
sterilization vs disinfection vs antisepsis vs sanitation
answer
  • Sterilization- killing of ALL living organisms
  • disinfection- killing or removal of pathogens from INANIMATE OBJECTS
  • antisepsis- killing or removal of pathogens from the SURFACE OF LIVING TISSUES
  • sanitation- reducing the microbial population to safe levels.
question
pasteurization
answer
  • not sterilization- it is the partial sterilization of foods at a temperature that destroys pathogens and more organisms, without changing the chemistry of the food. (ex: the pasteruizaton of milk)
question
Joseph Listers claim to fame
answer
  • developed carbolic acid to treat wounds and lcean surgical instruments
question
Define antibiotic. Why do I care? And why do i care that i take them all?
answer
  • antibiotics- chemical compounds synthesized by one microbe that kills or inhibits the growth of another microbial species.
  • if you stope takng them they will not completely kill the microbial species.
question
What is a virus?
answer
  • and obligatory intracellular parasites- contains DNA or RNA or double stranded
question
protein coat
answer
coats the outside of the virus
question
host range
answer
determined by specific host attachment sites and cellular factors.
question
lytic vs lyscogenic cycles
answer
  • lytic cycle- bacteriophage quicly replicates, killing host cell.
  • lysogenic cycle- bacteriophage is quiescent, integrates into cell chromosomes, as a phosphage. can reactivate to become lytic
  • In general, events that threaten host cell survival trigger a lytic burst
question
capsid
answer
  • composed of repeated protein subunites
  • this maximized the capacity while minimized the required number of genes
  • the capsid packages the viral genome and delivers it into the host cell
  • different viruses make different capsid forms

- symmetrical or asymmetrical

question
transduction? Prophage...
answer
  • transduciton- transpers DNA via phage particle
  • prophage- The genetic material of a bacteriophage, incorporated into the genome of a bacterium and able to produce phages if specifically activated.
question
viral genomes can be....
answer
  • can be...

-DNA or RNA

-single or double stranded

linear or circular

  • include genes encoding viral proteins

-capside

-envelope proteins

-any polymerase not found in host cell

question
types of viral genomes
answer
  • DNA viruses- can utilize the host replication machinery
  • RNA viruses- use an RNA-dependent RNA-polymerase to transcive their mRNA
  • retroviruses- use a reverse transciptase to copy their genomic sequence into DNA for insertion in the host chromosome.
question
six steps of the animal virus life cycles
answer
  • 1. attachment: viruses attach to cell membrame
  • 2. penetration- by endycytosis or fusion
  • 3. uncoating by viral or host enzymes
  • 4. biosynthesis: production of nucleic acid and proteins
  • 5. maturation: nucleic acid and capsid proteins assemble
  • 6. release by budding (enveloped viruses) or rupture
question
RNA viruses use an ___-dependent RNA polymerase to transcribe their mRNA
answer
  • RNA- dependent RNA polymerase.
question
retroviruses use a _________ to copy their genomic sequences into DNA
answer
- use a reverse transciptase to copy their genomic sequence into DNA
question
HSV primary infection is _______ but latent infecton can occur within ________. Why is this important to you?
answer
  • primary infection is epithelial
  • but latent infection can occur within neurons of ganglia
  • this is important because it can be triggered by stress
question
Poliovirus is transmitted by ____ route. Most cases result in mild _________. __% result in paralysis. First vaccine was the Salk vaccine which uses a _____ viral particle whereas the Sabin vaccine uses a ____ virus.
answer
  • fecal-oral route
  • gastrointestinal infection
  • 1%
  • innactive polio virus
  • attentuated polio virus
question
Infuenza A has a __ genome. Why is this imporant? H stands for _____ while N stands for ___ and why do I care?
answer
  • segmented genome- eight separate linear (-) strands of RNA
  • Hemagglutinin
  • Neuraminidase

^^ two major envelope proteins. H1/ N1 viruses.

question
What is reverse transciptase and why do I care?
answer
  • copies the RNA genome to DNA
  • 1. DNA synthesis from the RNA template

-primed by the host tRNA

  • 2. RNA degradaton: via RNase activity
  • 3. DNA-dependent DNA synthesis
  • -generates a dsDNA
question
Contast acute, lantent and persistent viral infections. Provide and example for each
answer

acute- short period of time, influenza

persistent- disease processes ovvurs over a long period; generall is fatal (ex HIV)

latent- virus remians in asymptomatic host cell for long period. (ex shingles, HSV)

question
Nonvirus and Rotavirus cause ___ and are especially fatal in _____ of the ______ world.
answer
  • gastroenteritis
  • children
  • developing countries
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New