L29 Flashcards

1
Q

Describe characteristics of archaea.

A

Hallmark = cell wall WITHOUT peptidoglycan

Don’t cause human disease

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2
Q

What are the 3 broad categories of bacteria by shape?

A
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
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3
Q

What is alpha vs beta vs gamma hemolysis?

A

On blood plates
Alpha = Hgb –> metHgb
Beta = complete hemolysis w/ zone of exclusion
Gamma = no hemolysis

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4
Q

What are the 4 structures seen in all bacteria?

A
  1. Cell envelope/membrane
  2. Cytoplasm
  3. Ribosomes
  4. 1+ chromosomes
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5
Q

Describe the cell envelope of gram + bacteria.

A

2 layers

  1. Peptidoglycan (outer)
    - THICK
  2. Phospholipid membrane (inner)
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6
Q

Which molecule is unique to the peptidoglycan layer gram + bacteria?

A

LTA = lipoteichoic acid

Spans the outer membrane & connects with phospholipid membrane

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7
Q

How many/what are the layers of gram - bacteria?

A

3 layers

  1. Asymmetrical outer membrane
    - LPS face outward
    - Phospholipids face inward
  2. Peptidoglycan in perimplasmic space
    - Smaller
  3. Phospholipid inner membrane
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8
Q

How many/what are the layers of acid fast bacteria?

A
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
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9
Q

What is the PAMP for gram +? PRR?

A
PAMP = LTA (lipteichoic acid)
PRR = TLR2
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10
Q

What is the PAMP for gram -? PRR?

A

LPS & TLR4

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11
Q

What is a fxn of the periplasmic space for gram -?

A

Barrier to non-polar molecules that enter through pores in the outer membrane before crossing in the phospholipid inner membrane pores

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12
Q

What color do gram +/- stain with crystal violet/safranin staining?

A

Gram + = purple

Gram - = red

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13
Q

What are the PRRs for acid fast bacteria?

A

TLR1/2/6

Various b/c the outer lipid covering of acid fast bacteria can be so variable

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14
Q

How do you stain acid fast bacteria?

A
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
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15
Q

What is the role of peptidoglycans in the cell wall?

A

Protects against changes in osmotic pressures

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16
Q

Describe the structure of peptidoglycans. What are the main 2 parts?

A
  1. Sugars = NAM & NAG

2. Linked by AAs

17
Q

What is the AA linkage order for gram + vs - bacteria?

A
\+ = alanine, glutamine, LYSINE, alanine, alanine
- = A, Glu, DI-AMINO-PIMELIC ACID, A, A
18
Q

How do D conformations of AAs confer natural protection for bacteria?

A

Body doesn’t have an D AAs

Aka our peptidases are meant for L AAs

19
Q

Which enzyme inserts and links NAG & NAMs together?

A

Transglycosylase

20
Q

Which enzyme forms the AA cross links between peptidoglycan layers?

A

Transpeptidase

21
Q

How do beta lactam antibiotics work? What some examples of beta lactam drugs?

A
Inhibits transPEPtidases 
Build up of peptidoglycan precursors 
Triggers digestion of existing peptidoglycans & inhibits synthesis on new ones
EXs:
- Penicillin
22
Q

Which types of bacteria do you find flagella on? Which don’t you?

A

On bacilli & spirochetes (mainly gram -)

NOT cocci

23
Q

Which direction do flagella move when they are attracted to something?

A

Anti-clockwise

24
Q

Which direction do flagella move when they are repelled?

A

Clockwise

25
Q

What are the 3 parts of flagella?

A

Basal body @ inner membrane
Hook @ outer membrane
Filament

26
Q

Which bacteria are monotichous?

A

1 flagella = monotrichous = vibrio

27
Q

What is a bacteria called if it has multiple flagella from 1 spot?

A

Lophotrichous

28
Q

What is a bacteria called if it has 1 flagella coming from each end?

A

Amphitrichous

29
Q

What is a bacteria called if it has many flagella? Give an example.

A

Peritrichous

E.Coli

30
Q

What is the difference between pili vs fimbriae?

A

Pili = gram + & -
- Longer, can connect between bacteria (transfer of genetic material)
Fimbriae = short, surrounds cell membrane
BOTH adhesion to surfaces and other bacteria

31
Q

What is the difference between capsule vs. slime layer?

A

Slime - important for life
- Protects from dehydration/loss of nutrients
Capsule - helps pathogenic mechanism
- Sticky, adhesion to host

32
Q

What is an endospore?

A

Cell reverting into hibernation for survival

Likely to be gram +

33
Q

What are plasmids?

A

Circular, dsDNA that can be transferred between viruses/bacteria to increase pick up/trade resistance markers
Can replicate on own in host