Exam one Microbiology – Flashcards

-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

- 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)

-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

• 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

• 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.

• 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

• 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

• molecules move along their concentration gradient

• molecules move against their concentration gradient- requires energy (it takes energy to make energy)

• 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)

• 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

• 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

• D- does not fit through ribosome
• L- fits through ribosome

• teichoic acids- provide strength (unique to gram positive)
• located in the cell envelope

• a capsule is not in every species it is made of polysaccharides (most pathogens have capsules)
• located in the cell envelope

• mycobacteria- complex cell
• excludes antibiotics and lots of nutrients-- results in malnutrition and slow growth
• mycolic acid- unusual membrane lipids

• a thin peptidoglycan layer consisting of one or two sheets covered by an outer membrane which confers defensive abilties

• 1. O polysaccharide- confers serotype specificity
• 2. core polysaccharide
• 3. lipid A - TOXIC0 overheating unit

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)

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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.

-phile- like

-phobe- dislike

tolerant- tolerate

• 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

• 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+.

• 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

• 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.

• 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)

• developed carbolic acid to treat wounds and lcean surgical instruments

• 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.

• and obligatory intracellular parasites- contains DNA or RNA or double stranded

• 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

• 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

• 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.

• 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

• 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.

• 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

• RNA- dependent RNA polymerase.

• primary infection is epithelial
• but latent infection can occur within neurons of ganglia
• this is important because it can be triggered by stress

• fecal-oral route
• gastrointestinal infection
• 1%
• innactive polio virus
• attentuated polio virus

• segmented genome- eight separate linear (-) strands of RNA
• Hemagglutinin
• Neuraminidase

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

• 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

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)

• gastroenteritis
• children
• developing countries