Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
Aerobe
|
only grows in the presence of oxygen
|
|
|
Anaerobe
|
only grows in the absence of air/oxygen
(will be killed by the presence of air/oxygen) |
|
|
Facultative anaerobe
|
grow both in the presence and absence of air
|
|
|
Growth locations in test tube based on gaseous requirement
|
Obligate aerobe: top surface
Micro-aerophile (likes a low level of oxygen): just beneath the surface Obligate anaerobe: very bottom Facultative anaerobe: spread throughout |
|
|
Mechanisms of genetic change
|
- spontaneous genetic mutation
- conjugation: DNA from donor bacterium is passed directly into recipient bacterium - transformation: taking up free DNA - transduction: DNA acquired via a bacteriophage |
|
|
Nucleoid
|
- condensed DNA in a prokaryotic cell
- consists of 30-50 loops of DNA emerging from a core, highly-condensed region |
|
|
Topoisomerase I
|
- removes supercoils by making single-stranded nicks
- present in all bacteria |
|
|
Topoisomerase II (DNA gyrase)
|
- adds supercoils
- present in all bacteria - four chains (two from gyrA gene, two from gyrB gene), target of antibiotics |
|
|
Biovars vs. Serovars vs. Morphovars
|
Biovars differe biochemically from each other
Serovars differ antigenically (different cell surfaces) Morphovars differ morphologically (look different under microscope) |
|
|
Steps of Gram stain
|
- heat-fix organism to slide
- crystal violet - iodine - decolorizer (washes away crystal violet only from Gram-neg) - safranin (stains Gram-neg pink) |
|
|
Acid Fast Stain
|
- used for organisms that are impermeable to Gram stain dyes
- acid fast organisms: stain red (retain Ziehl-Neelsen stain, aka carbol-fuchsin) - non-acid fast organisms: stain blue (counterstained by methylene blue) |
|
|
Nucleic acid hybridization
|
- used to determine how related two species are
- mix ssDNA from two species and determine the percentage of the DNA that can form dsDNA hybrids (the greater the percent hybridization, the closer the species) |
|
|
Pulsed field gel electrophoresis
|
- useful in characterizing the strain identity of outbreaks
- cut DNA with picky restriction enzymes (so they do not cut too frequently) - electric field pulses in different directions to help dislodge large pieces of DNA that may get stuck in the gel matrix |
|
|
Periplasmic space: location, contents
|
- only in Gram-neg organisms, between outer and inner lipid bilayers
- contains peptidoglycan layer, degradative enzymes (process nutrients, break down antibiotics), binding proteins for sugars/AAs, toxins involved in animal diseases |
|
|
Flagella
|
- mediates ability to swim/move
- seldom found on cocci (so cocci is basically immotile) - made of proteins |
|
|
Monotrichous vs. Lophotrichous vs. Amphitrichous vs. Peritrichous
|
Monotrichous- one flagellum
Lophotrichous- several flagella at the same end Amphitrichous- one from each end Peritrichous- many flagella randomly located all over cell |
|
|
CW vs CCW movement of flagella
|
CW: tumbles
CCW: moves in straight line |
|
|
Mechanism of chemotaxis
|
straight line movements are longer in the direction of the attractant
|
|
|
Pili (aka fimbriae)
|
- thin short filaments extending out of surface of Gram-neg cells
- made of self-aggregating protein monomers called pilin, often with adhesin protein at the tip - allow bacteria to adhere to eukaryotic cell surface - bacteria can undergo phase variation (replacing pili with different type of pili) to hide from immune system |
|
|
Sex pili
|
- male bacteria
- longer than regular pili - fewer in number (usually ~10) |
