L29 Flashcards
(33 cards)
Describe characteristics of archaea.
Hallmark = cell wall WITHOUT peptidoglycan
Don’t cause human disease
What are the 3 broad categories of bacteria by shape?
Cocci = round - Steptococci = line of round shaped bacteria - Staphylococci = grape formation Bacilli = oval - Steptobacilli Other - Fusobacterium = enlarged rod - B deliovibrio = comma - Helical form (helicobacter) - Spirochete
What is alpha vs beta vs gamma hemolysis?
On blood plates
Alpha = Hgb –> metHgb
Beta = complete hemolysis w/ zone of exclusion
Gamma = no hemolysis
What are the 4 structures seen in all bacteria?
- Cell envelope/membrane
- Cytoplasm
- Ribosomes
- 1+ chromosomes
Describe the cell envelope of gram + bacteria.
2 layers
- Peptidoglycan (outer)
- THICK - Phospholipid membrane (inner)
Which molecule is unique to the peptidoglycan layer gram + bacteria?
LTA = lipoteichoic acid
Spans the outer membrane & connects with phospholipid membrane
How many/what are the layers of gram - bacteria?
3 layers
- Asymmetrical outer membrane
- LPS face outward
- Phospholipids face inward - Peptidoglycan in perimplasmic space
- Smaller - Phospholipid inner membrane
How many/what are the layers of acid fast bacteria?
2.5 layers 1/2, Mycolic acid with lipid tails = outer 1. Peptidoglycans + cell waxes (sugars): LAM = lip-arabin-omannan ABG = ara-bino-galactan UNIQUE to acid fast bacteria 2. Phospholipid inner membrane
What is the PAMP for gram +? PRR?
PAMP = LTA (lipteichoic acid) PRR = TLR2
What is the PAMP for gram -? PRR?
LPS & TLR4
What is a fxn of the periplasmic space for gram -?
Barrier to non-polar molecules that enter through pores in the outer membrane before crossing in the phospholipid inner membrane pores
What color do gram +/- stain with crystal violet/safranin staining?
Gram + = purple
Gram - = red
What are the PRRs for acid fast bacteria?
TLR1/2/6
Various b/c the outer lipid covering of acid fast bacteria can be so variable
How do you stain acid fast bacteria?
Carbolfuchsin stain (targets cell waxes) No decolorization with acid alcohol Counter stain with methylene blue NET - Acid fast = red due to carbolfuchsin - Host cells or gram +/- = blue
What is the role of peptidoglycans in the cell wall?
Protects against changes in osmotic pressures
Describe the structure of peptidoglycans. What are the main 2 parts?
- Sugars = NAM & NAG
2. Linked by AAs
What is the AA linkage order for gram + vs - bacteria?
\+ = alanine, glutamine, LYSINE, alanine, alanine - = A, Glu, DI-AMINO-PIMELIC ACID, A, A
How do D conformations of AAs confer natural protection for bacteria?
Body doesn’t have an D AAs
Aka our peptidases are meant for L AAs
Which enzyme inserts and links NAG & NAMs together?
Transglycosylase
Which enzyme forms the AA cross links between peptidoglycan layers?
Transpeptidase
How do beta lactam antibiotics work? What some examples of beta lactam drugs?
Inhibits transPEPtidases Build up of peptidoglycan precursors Triggers digestion of existing peptidoglycans & inhibits synthesis on new ones EXs: - Penicillin
Which types of bacteria do you find flagella on? Which don’t you?
On bacilli & spirochetes (mainly gram -)
NOT cocci
Which direction do flagella move when they are attracted to something?
Anti-clockwise
Which direction do flagella move when they are repelled?
Clockwise
