8.31.2022. study questions Flashcards
Which molecule is unique to domain bacteria and not found in archaea or eukarya?
peptidoglycan
Draw the structure of peptidoglycan
NAG
NAM
tetrapeptide chain (AA)
peptide interbridge (G+ cells)
What will happen to abacterial cell if you weaken the structure of peptidoglycan?
weaken cell wall overall so then the cell could burst
What effect does lysozyme have on peptidoglycan?
disrupts the bond between NAG–NAM. more effective against G+
What effect does penicillin have on peptidoglycan?
prevents cross-linking of adjacent glycan chains by inhibiting the enzyme that normally catalyzes the cross-linking step
What gram cell types have porins and why?
gram negative. permit passage of molecules
Which molecule is unique to gram positive cells?
teichoic acids
How is the gram negative cell wall different from the gram positive cell wall?
Negative: thin layer of peptidoglycan. porins. LPS. outer membrane.
Positive: thick layer of peptidoglycan. teichoic acids.
Where is LPS found?
outer membrane of G- cell wall
What is the medical significance of LPS aka endotoxins?
- component of outer membrane of G- bacteria
- immune system can handle small quantities
- large quantities (like lots of G- in the bloodstream) are deadly
Why can mycoplasma species not be treated with penicillin?
But they do have…?
-no cell wall
- they do, however, have sterols in the cytoplasmic membrane that make it okay for mycoplasma to live without a cell wall
What staining technique is used to stain mycobacteria?
acid fast stain
Why can’t they stain mycobacteria with gram stain?
no cell wall
What are efflux pumps?
“eject pumps.” using energy to pump antibiotic drugs out of the cell, then the drugs don’t have an effect.
Why do efflux pumps need energy to function?
using difference in proton gradient to activate the pump to get stuff out of the cell and pump antibiotics out of the cell
What is the function of type three secretory systems?
poke and inject (not puncture) a cell. importance for virulence by causing changes in the host cell. they want the cell to live.
How are flagella beneficial for pathogenesis in gastric ulcers and lyme disease?
- helicobacter secrete urease to survive acidic environment
- Use flagella to attach and bore holes. Damage mucous-secreted cells
- inflammation and toxins damage epithelial cells
Give examples of three cell different cellular structures embedded in the cytoplasmic membrane?
porins, secretion systems, teichoic acids in G+
What are various pili useful for?
attachment
gliding/twitching
DNA transfer (sex pilus)
important pathogenic factor (no attachment = no infection)
What are plasmids?
extra chromosomal info in prokaryotes.
How are plasmids unique from the chromosome?
they contain “extra”/non-essential info.
Describe some characteristics that are commonly encoded on plasmids
NOT transcription or translation.
- ability to use specific uncommon nutrients
- ability to destroy antibiotics
- ability to produce toxins or other virulence determinants
- ability to be integrated into the chromosome (become the “episome”)
- transferred, spread among a population, and also lost
Give an example of a gene that is always found on the chromosome but not on a plasmid
transcription and translation
How are bacterial ribosomes different from eukaryotic ribosomes?
Why is this essential from a medical point of view?
70S vs. 80S
medications that affect one may not affect the other
What is an endospore? What are they resistant to?
a spore that develops inside some bacteria cells. made by bacteria. resistant to heat, drying, UV light, and chemicals.
Name the only two genera that produce endospores
Bacillus species
Clostridium species
Use the terms sporulate and germinate in describing the life-cycle of spore-forming bacterium
one vegetative (actively dividing) cell sporulates into one endospore. one endospore cannot divide or replicate. can’t even whistle. spore goes out of dormant phase to become vegetative cell, and germinates back into one cell.
what does not work to kill an endospore?
ABCD
1. alcohol
2. boiling at 100 degrees c
3. cleaning products
4. detergents
what does work to kill an endospore?
ABBDEE
1. autoclaving
2. burning
3. bleach
4. high doses of UV
5. long exposure to ionizing radiation
6. ethylene oxide
