Flashcards in Week 3 - Bacterial Growth and Microbe Structure -Ziegler Deck (55)
Outline the 4 steps of bacterial fission:
-replication of DNA
-generate a cross wall
What is the difference between doubling time and generation time?
They are both the same thing. Amount of time required to double the number of cells in culture is the generation time. And the time for one cell to become two is the doubling time.
Stages of the cell growth curve?
Lag phase: bacteria adapt to new environment
Log Phase: exponential growth, doubles fast
Stationary: nutrients exhausted and toxic products build up. Bacteria numbers stay constant
Death: Bacteria die of toxicity (not always)
Why do cells replicate slower in an abscess?
It is an area of low oxygen. So bacteria are only going to be using anaerobic growth. This is less efficient and consequently slower.
How are CFU's used to determine bacterial concentration?
Concentration is diluted and plated onto media
Each colony will then represent one bacteria from the original culture
REMEMBER: this will only represent viable bacteria
What are fermentation end products of Streptococcus, Lactobacillus, and Bacillus?
What are fermentation end products of Saccharomyces (yeast)?
Ethanol and CO2
What are fermentation end products of Propionibacterium?
Propionic Acid, Acetic Acid, CO2, and H2
What are fermentation end products of Clostridium?
Butyric Acid, Butanol, Acetone, Isopropyl Alcohol, and CO2
What are fermentation end products of Escherichia and Salmonella?
Ethanol, Lactic Acid, Succinic Acid, Acetic Acid, CO2, and H2
What are fermentation end products of Enterobacter?
Ethanol, Lactic ACid, Formic Acid, Butanediol, Acetoin, CO2, and H2
List a few things you should keep in bacterial growth media
The growth media must contain: carbon, nitrogen, sulfur, phosphorus, calcium, magnesium, potassium, iron, and other minerals in small amounts.
Iron is NOT required for the growth of Borrelia species (in other words, there are often exceptions).
What is a heterotroph?
Requires preformed organic compounds (sugars AA's, and vitamins)
What is an autotroph?
Can synthesize everything is needs from inorganic compounds like CO2
Obligate intracellular pathogen - requires organic compounds from host (viruses)
What carrier proteins help bacteria uptake important nutrients?
What does it mean to be an obligate aerobe?
Must have O2 for growth! No fermentation allowed!
What does it mean to be an obligate anaerobe?
These organisms are actually killed by O2. Use fermentation!
What does it mean to be a facultative anaerobe?
Can grow with or without O2
Why on earth is superoxide dismutase an important enzyme?
it gets ride of superoxide radicals, which is dang important for any aerobic organisms! Radicals cause a big ruckus if they are left sitting around.
4 differnt kinds of microbes are?
Why are ribosomes a good target for antibiotics?
Ribosomes are made differently between Euk and Prok
(it would be great if someone had more clarification for this one)
What is the shape of bacillus bacteria?
2 bacilli together? Chains? X,V,Y figures?
Shaped like rods
2 bacilli= diplobacti
Chains = streptobacilli
X,V,Y figures = palisades
What are the spherical bacteria called?
Spirochetes have what conformation?
FLEXIBLE undulating corkscrew
What kind of bacteria have a RIGID corkscrew shape?
What is the mesosome?
Chromosomal DNA attached to inner bacterial membrane near site of bacterial division
(wikipedia says this is hocus pocus?)
What kind of info usually on plasmids?
resistance to antibiotics and stuff
Why should a doctor care about flagella?
They can be targets for antibiotic therapies!
What are the two types of pilli? what do they do?
Adherence pili - attach bacteria to surface to cause disease in different locations in the body
Sex pili - bacterial conjugation in some gram negative bacteria. Genetic info can be transferred to other bacteria
What is the capsule in bacteria?
Slimy outer coating made of polysaccharides!
Not found in ALL bacteria
Why is peptidoglycan a good target for antibiotics?
It is a UNIQUE component of bacteria.
Gram positive have a lot of it!
How does penicillin hurt bacteria?
It destroys the crosslinks between chains of peptidoglycan monomers that surround the bacteria
Why do gram positive bacteria show up in a gram stain better than negatives?
The peptidoglycan cross-linking holds in the iodine-dye complexes and they sort of get stuck in the web of peptidoglycan. The gram negatives don't have a lot of that and so the dye doesn't stick around.
Are gram neg or pos bacteria entered more easily with large molecules?
gram negative allow large molecules in easier
Which molecules are found ONLY in the gram positive cell wall?
Found only in gram negative cell wall:
What is the periplasmic space in gram negative bacteria for?
Its a gel-like matrix between the cytoplasmic membrane and the outer membrane.
Contains enzymes for nutrient breakdown and substrate binding proteins
What do lipoproteins do?
THey cross-link the outer membrane to peptidoglycan in the periplasmic space
Lipopolysaccharide does what for gram negative bacteria?
It it AKA Lipid A or endotoxin
Very toxic to animals
The chain of polysaccharides coming of Lipid A is called O-antigen because it can be targeted as an antigen
What is mycoplasma?
Small organism with no cell wall that contains sterols
Talk about Acid Fast Bacteria!
Mycolic acids make the cell walls impermeable
Has very little peptidoglycan so gram stains dont work
USE acid-fast stain to identify!
What are protein sectretion systems?
The means by which bacteria transport things out of the cell or into other cells.
Can cause pathologies
If you were a bacteria and about to die of starvation what could you do to come back to life later?
Make yourself into an endospore.
You would have to be a bacillus or cloistridium species. That would make you resistant to heat, desiccation, or chemical damage.
You would have a of of calcium dipicolinate in your system at that point.
When identifying a virus, what arethe things you should look for?
IS it RNA/DNA?
Sort of like viruses, very small RNA. Mysterious. Similar to Hep D.
Name a few prion diseases:
Creutfeldt-Jakob disease in humans
or Kuru caused by cannibals
Mad cow disease
scrapie in sheep
If you want to attack a fungi, what is an important part of the membrane you can try to target?
Ergosterol is the dominant membrane sterol rather than cholsterol
3 types of fungi?
yeast, mushrooms, molds
Filamentous growth form of mold is?
masses of hyphae called mycelia!
WHy are fungi spore important for a future physician like yourself?
Because you can often identify the fungi by the type of spore
What are the motile and resting form of protozoa?
trophozites = motile
cysts = resting
What are the different temperature classifications for bacteria?
Psychrophiles: 0-20 Celsius
Mesophiles: 20-45 Celsius
Thermophiles: 45-90 Celsius
What is differential media?
Supplies nutrients or indicators to tell what kinds of organisms are present in the media