1 DD Bacterial Structure, Function and Growth Flashcards Preview

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Flashcards in 1 DD Bacterial Structure, Function and Growth Deck (41):
1

List structural features of bacteria

1. Capsules
2. Pili aka Fimbriae
3. Rigid external cell wall
- Peptidoglycans
4. Cytoskeletal elements
5. Cytoplasmic membrane
6. Flagella

2

Capsule:
- describe
- purpose
- Why do we even care?(How do we take advantage of it?)

a. Outer complex polysaccharide layer→ Gelatinous and loose as a goose

b. Purpose: protects against phagocytosis → "enhance virulence"

c. Most capsular polysaccharides are antigenic →used as components of vaccines to prevent bacterial infections

3

Pili "fimbriae"
- describe
- purpose
- Why do we even care?(How do we take advantage of it?)

a. Long, slender, antigenic hair-like glycoproteins on surface

b. Function: bacterial adherence
i. Some (few) bacteria: sex pili → bacterial conjugation

c. Can make antibodies against pili → block bacterial adherence → resist bacterial infection

4

Peptidoglycans
- describe
- purpose
- Why do we even care?(How do we take advantage of it?)

a. Rigid polymer of repeating NAM and NAG. Makes up external cell wall

b. Purpose:
i. Structure and strength for cell wall (not shape)

c. Peptidoglycans are unique to bacteria- → great target for antibiotics.

5

Rigid external cell wall
- describe
- purpose

a. Made of peptidoglycan in Gram (+)
Made of peptidoglycan and outer membrane in Gram (-)

b. Purpose: Cell shape + resisting osmotic lysis

6

Describe differences in Peptidoglycan content in gram (+) vs gram (-) bacteria

Gram (+) bacteria: greater extent of peptidoglycan cross-linking
**Gram Positive: think P for Puffier Peptidoglycan

Gram (-) bacteria: lesser extent of peptidoglycan cross-linking
** Gram Negative: think N for Not as much peptidoglycan

7

What is another name for the two hexose, NAG and NAM?

N-acetylglucosamine (GlcNAc or NAG)

N-acetylmuramic acid (MurNAc aka NAM)

8

Intracellular cytoskeletal elements
- purpose
-describe its components

a. Purpose: Determines cell shape

b. Bacteria tubulin: FtsZ
c. Bacteria actin: MreB and ParM
d. Bacteria Intermediate filament protein: CreS (crescentin)

9

Cytoplasmic membrane
- describe

Lipid bilayer of phospholipids and lots of proteins (60-70%)

- Anatomical physiological barrier between inside and outside of cell

10

List different functions of cytoplasmic membrane (6)

i. Selective permeability
ii. Electron transport
Iii. Transport of metabolites
iv. Biosynthesis of lipids and cell envelope components
v. DNA replication
vi. Flagellar rotation

11

Flagella
- purpose
-types of movement

Function: motility → used to move bacteria during chemotaxis
i. Counter-clockwise: swimming (unidirectional)
ii. Clockwise: tumbling (ie clumsily changing direction)


12

Types of Flagella

i. Polar: 1 or several flagella at 1 end
ii. Peritrichous: flagella distributed over surface

13

Whats another name for cytoplasmic membrane? In which Gram type of bacteria would you use this name?

Inner membrane in Gram (-) bacteria

*note: gram (-) bacteria also have an outer membrane

*gram + bac have no outer membrane - only 1 general plasma membrane

14

Whats another name for Pili?

Fimbriae

15

Why do we care about flagella?
example

Most are antigenic → can be used for classification
1) Ie: H antigens of enteric bacteria

16

List bacterial structures that are antigenic

capsules
pili
Flagella

17

Nucleoid

aka nuclear body - where DNA is located in bacteria


18

Whats the difference between bacteria chromosome and plasmid?
- give an example of a plasmid

i. Chromosome: a single, double-stranded, circular DNA molecule

ii. Plasmid: smaller, extra-chromosomal, self replicating DNA molecules → code for virulence factors
1) Ie: R factors: plasmids that carry genes that determine resistance to antibiotics

19

Describe layers of Gram (+) bacteria

2 layers total:
- 1 layer of cell wall:
□ Thick, extensively linked peptidoglycan layer containing teichoic acids
- 1 plasma membrane layer

Lipotechoic acid underneath cytoplasmic membrane

20

Lipoteichoic acid:

found attached to underlying cytoplasmic membrane of gram + bacteria → anchor cell wall (peptidoglycan) to membrane

- only found in gram +

21

Teichoic acid

Repeating bacterial polysaccharides (polyglycerol-P aka Polyribitol-P backbone) → extends peptidoglycan surface

-only found in gram +

22

Describe layers of Gram (-) bacteria

3 layers total:
2 layers of cell wall:
□ Outer membrane
□ Thin, sparsely linked peptidoglycan layer
1Plasma membrane

23

Function of outer membrane of Gram (-) bacteria

□ Barrier against antibiotic entry
□ Protection against detergents and toxic compounds

24

Components of outer membrane of Gram (-) bacteria

lipopolysaccharide (LPS), lipoproteins, and porins

25

lipopolysaccharide (LPS)

polysaccharide containing
1. Lipid A
2. Core polysaccaride
3. O side chain oligosaccharides

26

Lipid A and O side chain oligosaccharides
-Where are they found and What are they:

Found in LPS of outer membrane of Gram - bacteria

Lipid A - the toxic component of endotoxin

O side chain oligosaccharides - function as somatic antigens aka O antigen

27

Phases of bacterial growth curve

1. lag phase
2. exponential(logarithmic) phase
3. Stationary phase
4. Death phase

28

Based on classifications of energy sources, the majority of bacteria are?

Heterotrophic - requires organic carbon

29

autotrophic organisms

obtain carbon exclusively from CO2

30

Fastidious organisms

requires carbon and essential growth factors (aa, vitamins, purines, pyrimidines, inorganic ions)

-Deficient in 1/more biosynthetic pathways → requires rich growth media

31

Facultative anaerobe

respires w/ low O2
ferments in absence of O2

32

What type of bacteria grows best at low O2 [ ], AND
can grow without O2?

microaerophilic

33

Which energy currency is used for flagellar rotation?

Proton motive force (PMF)

34

Fermentation

catabolic process in which organic compounds serve as both e- donor and acceptor

35

Do heterotrophic bacteria use fermentation or respiration to generate energy and reducing power?

Both

36

List antimicrobial agent targets

1. Cell wall
2. Outer and cytoplasmic membrane
3. Protein synthesis at ribosome levels
4. Nucleic acid synthesis.
5. Metabolism

37

What bacterial structures are unique to gram + bacteria?

lipoteichoic acid

38

What bacterial structures are unique to gram - bacteria?

porins
LPS endotoxin
periplasmic space (beta lactamase location)

39

Name for Bacteria tubulin

FtsZ

40


Name for Bacteria actin

MreB and ParM

41

Name for Bacteria Intermediate filament protein

CreS (crescentin)