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Bacterial Cell Structure

Objectives: 1) List the three parts of bacterial taxonomy. 2) Compare and contrast gram-positive, gram-negative and Acid Fast cell envelopes with regards to structure and chemical composition 3) Describe the Gram stain procedure 4) List the 3 components of bacterial cell envelopes that are highly toxic to mammalian cells. Describe their chemical composition 5) Describe the general role capsules, flagella, pili and cell surface proteins play in bacterial virulence 6) Describe the morphologi…
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List the three parts of bacterial taxonomy?
1) Archae
2) Eukyra
3) Bacteria
What is the concept of taxonomic rank and what is the order from highest to lowest? (7)
highest-
1) Domain
2) Phylum
3) Class
4) Order
5) Family
6) Genus
7) Species
lowest
What is a way to remember the bacterial taxonomic rank system?
Damn
PHISH
Caught
Ordinary
Flu
Going
South
What are some typical bacterial cell membrane components?
1) flagellum
2) pili
3) capsule
4) cell envelope
What role do flagella, pili and capsules play in bacterial virulence? (3)
1) capsules - adherence/attachment
2) flagella - getting away from immune system
3) pili - attachment to surfaces
What are the three parts of bacterial taxonomy?
1)classification
2) identification
3) nomenclature
What is classification?
orderly arrangement of bacteria into groups
What is identification?
practical use of classification criteria to distinguish certain types of bacteria from others
What is nomenclature?
the means by which characteristics of a species are defined and communicated among microbiologists
What are the different ways you can classify bacterial cells according to the way they look? (2)
1) way the cell is shaped (morphology)
2) cell arrangement
What is the primary function of flagella on bacteria?
motility to nutrients or away from toxic chemicals
What does clockwise movement of flagella cause?
tumbling
What does counterclockwise movement of flagella cause?
straight line movement
What is the main difference between fimbrae and sex pili? (structure and function)
fimbrae- numerous short and thin and are for cell attachment
sex pili- are longer, thicker and less numerous and are for mating
What are the four functions of bacterial capsules?
1) cell attachment
2) source of growth substrates
3) resistance to phagocytosis and dessication
4) influence tissue trophism
What are the two mainways that bacteria differ in terms of their cell envelope?
1) amount of peptidoglycan
2) lipids
Order the three types of bacteria according to their peptidoglycan layer thickness?
gram pos >>> gram neg = acid fast
Match the type of bacteria with their lipoprotein? gram positive
gram pos - lipotehichoic acid and teichoic acid
Match the type of bacteria with their lipoprotein? gram neg
lipopolysaccaride
Match the type of bacteria with the lipoprotein? acid-fast
mycolic acid, arabinogalactan, sulfolipids
What is on the outer membrane of gram negative bacteria? (3)
1) LPS
2) porins
3) lipoprotein
What is on the inner membrane of gram negative bacteria? (3)
it IS the cytoplasmic membrane
1) nutrient xporters
2) electron transport chain
3) biosynthetic enzymes for LIPS and peptidoglycan
So which is the type of bacteria cell with multiple layers?
gram negative is the one that has the multiple layers
What are the two alternating sugars that form the backbone of peptidoglycan?
N acetyleglucosamine (NAG)
N acetylmuramic acid (NAMA)
What are the steps of the gram stain? (5)
1) Add crystal violet
2) Add iodine
3) Decolorize with alcohol and acetone
4) Add safranin
When does the gram negative organism lose the christal violet?
after you add the alcohol-aceton and decolorize
What does the gram neg cell look after you add safranin?
red
What does the gram positive cell look like after you add safranin?
violent/purple
What are the general steps of peptidoglycan biosyntehsis? (3)
1) insid ethe cell the precursor is synthesized
2) transport across the plasma membrane
3) final assembly and cross linkage
What are the two antibiotics that work on step one of the peptidoglycan synthesis cascade?
1) fosfomycin
2) cycloserine
Where does fosfomycin work in the peptidoglycan synthesis cascade?
fosfomycin is a PEP analog inhibiting UDB muramic acid biosyntehsis
Where does cycloserine work in the peptidoglycan synthesis cascade?
analog of D alanine and competitively inhibits the conversion of L-alanine to D-alanine and the synthesis of D-ala and D-ala
What must happen to the fosfomycin and cycloserine antibiotics for them to be effective?
they must be taken into the cell
What are the three antibiotics that work in the step 2 of the peptidoglycan synthesis cascade? (3)
1) Vancomycin
2) Ristocetin
3) Bacitracin
Where does vancomycin and ristocetin work?
1) binds D-ala-D-ala so it cant be transferred to receptor
How does bacitracin work?
inhibits dephosphorylation of lipid carrier by binding the Pi
What two antibiotics work at the third stage of peptidoglycan synthesis?
1) penicillin
2) cephalosporine
Where is the action of penicillin and cephalosporine?
they inhibit transpeptidase which basically does the crosslinking in the final stage of peptidoglycan synthesis
What is the action of quinolones?
they inhibit bacterial DNA gyrase
What is the action of rifampin?
they inhibit the B subunit of bacterial RNA pol
What is the action of tetracyclines and aminoglycosides?
inhibit protein synthesis at 30s ribosome
What is the action of cholorophenicol, erythromycin and clindmycin?
bind to 50s ribosome
What is the mechanism of action of sulfa drugs? (2)
inhibit folic acid synthesis by acting as compeitive inhibitors of PABA
What is the mechanism of timethropim, aminoterin and methotrexate?
inhibits bacterial dihydrofolate reductase
What are the three parts of the lipopolysaccharides?
1)lipid A
2) core polysaccharide
3) O side chain (O antigen)
Which part of the LPS is most pathogenic
lipid A
Does gram negative or gram positive bacteria have periplasmic space
gram negative
What is the difference in the ring structures between gram positive and gram negative bacteria?
gram positive- 2 rings in basal body
gram negative - 4 rings in basal body
Which has the greater resistance to physical disruption, gram neg or gram post? why?
gram positive because of that huge ass peptidoglycan layer
Where can you find mycolic acids? (2)
Genera: 1) mycobacterium 2)nocardia
What are mycolic acid?
alpha substituted beta hydroxy fatty acids
What is cord factor?
a trehalose that mycobacterium tubercolosus cell envelopes contain that is linked to mycolic acid
What are the two genera of pathogenic bacteria that sporulate (2)?
1)Bacillus
2) clostridium
What is the chemical mediator that htelps bacterial spores resist heat, toxic chemicals etc?
calcium dipclonic acid
Penicillin ____
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Penicillin - C. Stage 3 of Cell wall biosynthesis
Chloramphenical _____
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Chloramphenical - I - Binds to 50S Ribosomal subunit
Steptomycin ____

A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Streptomycin H - Binds to 30s ribosomal subunit
Rafampicin _______
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Rafampicin - D - Inhibits transcription
Sulfanamide ______
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Sulfonamides - E- Compeittive inhibitor of Folic Acid Biosynthesis
Cycloserine ___________
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Cycloserine A Stage 1 of Cell wall biosyntehsis
Bacitracin ________
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
B - Stage 2 of cell wall biosynthesis. Blocks it when its going on to the carrier.
Quinolones ________
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
Quinolones - G - Inhibits DNA gyrase activity
Clindamycin _____
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
I - Binds to 50S ribosomal subunit
Tetracycline ________
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
H - Binds to 30S ribosomal subunit
Trimethoprim ________
A. Stage 1 of cell wall biosynthesis
B. Stage 2 of cell wall biosynthesis
C. Stage 3 of Cell wall biosynthesis
D. Inhibits transcription
E. competitive inhibitor of folic acid biosyntehsis
F. Membrane
G. Inhibits DNA gyrase activity
H. Binds to 30S ribosomal subunit
I. Binds to 50S ribosomal subunit
J. INhibits binding of mRNA to 30s Ribosomal subunit
K. Binds to B subunit of bacterial RNA pol
E - Competitive inhibitor of folic acid biosynthesis
What are the 8 steps of sporulation?
1) cell division
2) axial filament formation
3) septum formation
4) engulfment of forespore
5) cortex formation
6) coat synthesis
7) completion of coat synthesis, increase in refractility and heat resistance
8) lysis of sporangium, spore liberation