Bacteria 2 Flashcards
1
Q
flagella
A
- long polymers of flagellin that protrude from the cell wall: a bacterium may have one or several polar flagella at one end or be covered in them
- corkscrew shaped
- rotate to propel bacterium
- NOT WHIPLIKEEEEEEE
- rotated by molecular motor
- powered by an electron gradient at base
- gram neg have an extra set of wheels for outer membrane
2
Q
ribosomes
A
- 70s instead of 80s
- S=Svedberg-unit of sedimentation in a cesium chloride gradient under ultracentrifugation
- chemical differences are good target for drugs
- > 50% drugs target ribosomes
3
Q
aminoglycosides
A
- attack small subunit
- interfere with initiation and accuracy
4
Q
tetracyclines
A
- small subunit
- transfer of tRNA+aa sets to ribosome
5
Q
macrolides
A
attach rRNA of large subunit
-elongation
6
Q
spores
A
- survive in extreme environmental conditions by assuming a very rugged dormant form
- triggered by nutrient depletion
- bacterial genome and minimal entourage of macromolecules are compressed in a thick spherical coat that can survive high temperatures, dehydration, antiseptics, antibiotics
- when nutrients and water are plentiful-spore unpacks into normal form
- reason we autoclave-steam at 121 C or ethylene oxide
- replicates genome, divides into small and large–large mother cells is sacrificed and hard outer coat is grown.
7
Q
Binary fission
A
- logarithmic growth under optimal conditions-just duplicates and splits
- don’t usually limit growth
- very large progeny in very short time
- limited by available nutrients, what species it is, any toxic factors
8
Q
lag phase
A
- sense new environment and upregulate gene products for metabolism and growth
- liquid culture appears clear
9
Q
log phase
A
- rapid cell division with an exponential growth curve
- culture slightly cloudy
10
Q
stationary phase
A
- nutrient depletion and waste accumulation force growth rate down to match death rate
- very cloudy
11
Q
death phase
A
- waste accumulation kills off most remaining bacteria
- sediment on bottom
- pellicle on top
- middle cloudy with chunks
12
Q
obligate anaerobes
A
- derive ATP from Fermentation and can’t detoxy oxygen radicals
- lack catalase enzymes or superoxide dimutase
- can’t grow or die in oxygen
- botulism grows in anaerobic mason jar
- glycolysis–>pyruvate (gains two ATP)–>lactate (gains 2 NAD+)
13
Q
fermentation pathways
A
- inefficiently derive small amts of ATP from breaking chemical bonds of organic molecules
- uses the intermediate wast product (usually pyruvate) as an electron acceptor to reoxidize the used coenzymes, regenerating them and creating final waste product
- leave considerable chemical energy in final waste product, which may then be further broken down by neighboring bacteria of different types
- final waste products are usually organic acids or alcohols, detectable in lab by pH indicators or gas chromatography
- each type of bacteria has a repertoire of molecules that it can ferment and waste products that it produces- used for lab ID
14
Q
obligate aerobes
A
- exclusively derive ATP from e- transport ending in oxygen
- glycolysis, TCA, e-transport, proton gradient, oxygen to make water and ATP-see picture
- tuberculosis needs o2
- need oxygen because it is there terminal electron acceptor
15
Q
respiration pathways
A
- very efficient- >30 ATP
- glycolysis, TCA, E-transport
- some environmental bacteria can start with inorganic molecules
- require the ability to detoxify the reactive oxygen radicals produced in chain- oxidase, cytochrome, superoxide dismutase, catalase
- require a terminal electron acceptor
- normally oxygen, rarely nitrate, nitrite, ferric iron, sulfate, co2, small organic molecules
