Lecture 4

Question 1

What are the 4 types of envelope modifications in prokaryotes?

Answer 1

1) Capsules and slime layers
2) S-layer
3) Flagella
4) Pili

Question 2

What is a tightly attached “slime” called?

Answer 2

capsule

Question 3

What is a loosely attached “slime” called?

Answer 3

slime layer

Question 4

What is “slime” made of?

Answer 4

high-molecular-weight polysaccharide

Question 5

Is the slime layer/capsule a target for vaccines? why?

Answer 5

yes, bc it’s the first bacterial structure encountered by immune system

Question 6

What is capsular polysaccharides (CPS) usually composed of? charge?

Answer 6

typically negatively charged and can form 200 sugars long

Question 7

Serotyping uses what to help distinguish isolates?

Answer 7

CPS

Question 8

What allows insertion of the CPS into the membrane?
name? attached by what?

Answer 8

a phospholipid attached to the end of the CPS (hydrophobic)
called lyso-phosphatidylglycerol attached by Kdo linker

Question 9

What are the 4 functions of the capsule?

Answer 9

1) acts as a sponge to retain water and nutrients
2) protection against desiccation
3) limits diffusion of harmful chemicals
4) aids in surface adherence and biofilm formation

Question 10

How does the capsule protect against immune evasion?

Answer 10

protects against complement system
and via cationic antimicrobial peptide resistance (positively charged and bacteria is negatively charged)

Question 11

How can you assay for capsule in the lab? (4)

Answer 11

1) Electron microscopy
2) calcofluor
3) biochemical isolation
4) capsule stain

Question 12

Procedure of capsule stain?

Answer 12

1) coat with india ink
2) air dry (heat melts sugar in capsule)
3) saturate with crystal violet for 1 min
4) rinse with water and air dry, look under microscope

Question 13

What is the role of the s-layer?

Answer 13

protection, structural support, permability barrier, mediate binding

Question 14

Where is the s-layer found?

Answer 14

bacteria and archea

Question 15

Where is the s-layer? for bacteria

Answer 15

anchored to the cell wall of Gram-positive bacteria and to the outer membrane of Gram-negative bacteria

Question 16

Where is the s-layer? for archea

Answer 16

either cell wall or directly to the cell membrane

Question 17

What is the s-layer made of? unique ability?

Answer 17

glycoproteins
can self assemble

Question 18

What is the role of flagella?

Answer 18

locomotion

Question 19

what is flagella at the end of a cell called?

Answer 19

polar

Question 20

what is flagella all over the cell called?

Answer 20

perotrichous

Question 21

more than one flagella?

Answer 21

flagellum

Question 22

What is the structure of a flagellum?

Answer 22

1) long helical filament
2) connecting hook
3) basal body equipped with a rotor to turn the flagellum

Question 23

Wha is the rotor power by?

Answer 23

proton motive force

Question 24

What is the flagellum filament made of? structure?

Answer 24

rigid helical hollow structure made of flagellin that self-assembles

Question 25

What is it important that the flagella is highly antigenic?

Answer 25

immune system can recognize

Question 26

What is the structure of the hook?

Answer 26

short joint, curved

Question 27

What is the basal body made of?

Answer 27

around 15 proteins that form a rod and anchors structure to cell membrane

Question 28

What does CCW rotation move the bacteria?

Answer 28

foward

Question 29

What does CW rotation move the bacteria?

Answer 29

tumble in place

Question 30

how is a random walk produced?

Answer 30

alternating CCW and CW

Question 31

What are endoflagella? ex?

Answer 31

flagella contained within periplasm, ex spriochetes

Question 32

Why do few gram-positive bacteria have pili?

Answer 32

pili attach to the outer membrane which Gram+ bacteria do not have

Question 33

Do pretty much all Gram- have pili or fimbriae?

Answer 33

yes

Question 34

What are pili or fimbriae?

Answer 34

thinner and shorter flagella distributed in large numbers over the surface

Question 35

Function of pili or fimbriae? (3)

Answer 35

1) attachement to surfaces 2) conjugation (transfer DNA/RNA) 3) motility

Question 36

What is pili composed of?

Answer 36

oligomeric pilin proteins

Question 37

what is the bottom/base of the pili called?

Answer 37

pilus

Question 38

what is twitching motility?

Answer 38

pili are sticky and this is how they move, extends and retraction due to polymerization and depolymerization

Question 39

How do we assay motility in the lab?

Answer 39

1) dip sterile toothpick into bacterial suspension 2) poke swim agar with toothpick 3) incubate at desired temperature and measure zone of motility

Question 40

what is the zone of motility?

Answer 40

diameter of colony

Question 41

How do we know which part of the flagellum are crucial for motility?

Answer 41

mutants lose parts of flagellar apparatus and look for small zones of motility in assay motility