29. Bacterial Structure and Characteristics Flashcards Preview

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Flashcards in 29. Bacterial Structure and Characteristics Deck (54):
1

archaea vs bacteria

archaea: ancient, single cell, cell wall differences to bacteria, LACK PEPTIDOGLYCAN, no human pathogens

bacteria: NO NUCLEAR MEMBRANE, distinct biochem and RNA markers, asymmetrical membrane

2

structural components (fimbriae, capsule, flagellum), cell wall (gram + or -), and genetic makeup are three general ways to ____ bacteria

classify

3

obligate aerobes _____ oxygen

require

4

microaerophiles ______ oxygen

require reduced

5

obligate anaerobes _____ oxygen

require no

6

facultative anaerobes ____ oxygen

they are anaerobic or aerobic

7

capnophiles _____ oxygen

require INCREASED CO2

8

what are 6 general levels we use to classify bacteria?

1. shape
2. gram reaction
3. atmosphere
4. spores
5. biochemisty/genetic classification
6. serology typing

9

what shape to staphylococci make?

like grapes

10

what shape to vibrio make?

like a comma

11

what shape do Bdellovibrio make?

comma with a tail

12

what shape do borrelia burgdorgeri make?

corkscrew

13

what shape does syphilis make?

spirochete

14

what shape does helicobacter pylori make?

helical

15

what shape are palisades?

bacili lined up in columns

16

are cocci normally gram - or +?

+

17

are bacilli normally gram - or +?

-

18

what is a red blood plate vs a chocolate blood plate?

RBCs intact in red, RBCs popped in chocolate (see iron)

19

what do alpha bacteria do on a red blood plate?

start to get conversion of hemoglobin to methemoglobin so turns brown

20

what do beta bacteria do on a red blood plate?

complete hemolysis - no RBCs around bacteria

21

what do gamma bacteria do on a red blood plate?

nothing

22

what 4 structures are common to all bacteria?

cell membrane/envelope

cytoplasm

ribosomes

one (or a few) chromosomes (eg E. coli technically has one but the chromosomes replicate at a different rate than the cell can divide so often find multiple in one cell)

23

layer number for each:

gram +
Gram -
acid fast

gram + (2 layers)
- cell wall (peptidoglycan)
- cytoplasmic membrane

gram - (3 layers)
- cytoplasmic membrane
- cell wall
- outer membrane

acid fast bacteria (2.5 layers)
- cytoplasmic membrane
- cell wall
- acyl layer

24

gram + cell wall structure?

- thick peptidoglycan cell wall (40+ layers)
- resists lysis by complement
- teichoic acids and lipoteichoic (LTA) polymers
- other proteins and carbs (enzymes/adhesions)
- TLR2 recogntion (LTA)
- inner membrane has 2 leaflets and is symmetrical, outer is NOT

25

gram - cell wall structure?

- asymmetric outer membrane (outer leaflet composed of LPS, inner leaflet of peptidoglycans)
- thin peptidoglycan layer
- periplasmic space b/w membrane (aqueous)
- barrier to non-polar molecs
- outer membrane porins (nable diffusion across outer membrane, barrier to large polar molecs)
- TLR4 recognition (LPS)

26

acid fast cell envelope?

- most similar to gram-positive cells (mycobacteria...so hard to treat thanks to the novel molecules in its membrane)
- cell wall comprised of fatty acids and waxes
- lipid components difficult to stain but once stained, stay stained
- mycolic acid, WAX D (much more rigid), arabinogalactans and sulfolipids present in cell wall
- TLR1/2/6 recognition

27

steps to gram stain?

fixation - crystal violet - iodine treatment (crosslinks peptidoglycan to change it from porous to tight closed so that gram+ retains violet) - decolorization - counter stain safranin (red)

28

what pathogens have acid fast cell wall?

mycobacterium

29

acid fast staining procedure?

- stain with carbolfuchsin
- resists decolorization with acid alcohol
- counter stain with methylene blue

30

peptidoclygan cell wall is unique to what?

prokaryotes

31

the peptidoglycan is what?

polymer consisting of 2 sugars and 5 aa's that forms a mesh-like layer outside of the cytoplasmic membrane

- gives strong structural support (gram + thick, 90% dry weight; gram - thin, 10% dry weight)
- rigid (protects vs osmotic pressures)
- involved in bacterial replicatoin
- TARGET OF MANY ANTIBIOTICS

32

sugars of the peptidoglycan prokaryotic cell wall?

NAG and NAM (alternating)

they make up the backbone and they are cross linked by peptides and there are tetrapeptide cross chains to keep Nag and Nam together

33

gram + amino acids of NAM/NAG peptidoglycan monomer?

L-alanine
D-glutamine
L-lysine
D-alanine
D-alanine

34

gram - amino acids of NAM/NAG peptidoglycan monomer?

L- alanine
D- glutamic acid
meso diaminopimelic acid
D-alanine
D-alanine

35

what makes the aa's pentapeptide of the prokaryotic peptidoglycan unique?

has D-forms of aa's that do not occur in human proteins and are thought to help vs attack by peptidases

36

enzymes required for peptidoglycan synthesis?

transglycosylase (inserts and links new peptidoglycan monomers)

transpeptidase (forms the peptide cross-links between the rows and layers of peptidoglycan) *** common target to keep bacteria from replicating

37

bacterial motility with flagella - forward vs backward motion

anticlockwise rotation: forward movement, swimming (chemoattractant)

clockwise rotation: tumbling movement, reorientation

38

flagella are present on which types of bacteria?

bacilli and spirochetes, but not cocci (so don't see on gram +, ie never see staph and strep w/flagella)

39

3 parts of flagella?

filament, hook (sheath), and basal body

40

what is a single flagella called- what is an example?

monotrichous (vibrio)

41

what are multiple flagella from one spot called?

lophotrichous

42

what are one flagella from each end called?

amphitrichous

43

what are many flagella in multiple directions called - what is an exam?

peritrichous (E.coli)

44

pili/fimbriae are present on gram+ or gram- bacteria?

both

45

what motility is afforded thanks to fimbriae?

twitching motility - grappling hook (type IV)

gives adhesion to surface and each other

46

fimbriated strains of E.coli can do what to RBCs?

agglutinate

47

how are pili used in bacterial sex?

exchange of genetic material = CONJUGATION

48

are fimbriae or pili longer?

pili

49

do gram+ or gam- bacteria have glycocalyx?

both

50

what is the purpose of the glycocalyx?

helps the cell adhere ot the env't (biofilm) or is a virulence factor

and protects bacteria from phagocytes - keeps macrophages at arm's length, looks like host, and really big for macrophages to engulf

51

slime layer vs capsule glycocalyx?

slime layer: loosely assoc with the cell
- protects from dehydration and loss of nutrients

capsule: firmly attached to cell wall (so doesn't slough off)
- gummy, sticky consistency
- protects similar to slime layer
- adhesion to surfaces and nutrients

52

endospores are found in gram+ or - bacteria?

certain gram+ (bacillus and clostridium)

53

what is the endospore?

a dormant, tough, and temporarily non-reproductive structure

- resistant to extreme heat/radiation but can be destroyed by autoclave or burning
- mult layers
- when env't returns favorable,it can germinate itself

some have crystals of nutrients too

54

classes of plasmids?

fertility plasmids - conjugation

resistance plasmids - resistance vs antibiotics

col plasmids - contain genes that code bacteriocins that kill other bacteria

degradative plasmids - digestion of unusual substances

virulence plasmids - turn bacterium into a pathogen