Exam 1 Lecture 4

Question 1

Structure in order from outside to inside of Gram-negative bacteria?

Answer 1

1. LPS
2. Outer Membrane has Porins-beta barrels(Ompf) and non-specific channels
3. Brauns Lipoprotein (connects outer membrane to the wall)
4. Cell wall- a single layer of peptidoglycan
5. Inner Membrane

Question 2

LPS structure from outside to in?

Answer 2

1. O-antigen polysaccharide (can change to avoid immune system) up to 200 sugars also called the repeating unit
2. Core polysaccharide varies with species 5-10 sugars
3. Lipid A- tails embedded in outer membrane has 2 parts
   a. disaccharide diphosphate
   b. 6 fatty acid tails

Question 3

Name 1 good and 1 bad function of LPS?

Answer 3

1. Resistant to phagocytosis
2. Can act as a receptor for virus/phages

Question 4

Basic characteristics of mycobacteria cell envelope?

Answer 4

Thick waxy and hydrophobic

Slow growing

Question 5

Basic structure from inside to out?

Answer 5

1. Cell membrane
2. Peptidoglycan layers

3 Arabinogalactan layer (Galactan then Arabinam)

4. Mycomembrane (mycolic acids, has porins)
5. Capsule (sugar mycolates then glycolipids)

Question 6

What is an S-layer?

Answer 6

Surface Layer composed of protein and glycoproteins

Highly ordered crystalline sheet with 2-8 nm large pores

Often lost in lab in Rich media

Question 7

What does and S-Layer do?

Answer 7

Protection and structural stability

(not needed in a media-rich lab environment so often lost)

Question 8

Who has an S-layer?

Answer 8

A lot of archaea and some bacteria

Question 9

What does S-layer link to?

Answer 9

Archaea- pseudo PG or membrane

Gram-pos- PG

Gram-neg- LPS

Question 10

What is the glycocalyx?

Answer 10

A polysaccharide (some protein) layer outside the cell wall

Either Capsule or Slime

Question 11

Who has a glycocalyx and what does it do?

Answer 11

Most Prokaryotes

1. Attachment and adhesion to substrates (plaque)
2. Protection against desiccation and phagocytosis

Question 12

Difference between Slime and capsule?

Answer 12

Capsule is discreet and contained, slime is loose

Question 13

Does a capsule have a role in pathogenesis?

Answer 13

Yes, many bacteria need the capsule for protection for their ability to infect host cells.

Experiment- living non-capsulated bacteria injected = no death

Living non-capsulated bacteria and dead capsulated bacteria injected = death

Living bacteria took capsules from dead and infected

Question 14

Examples of pathogenic bacteria that require a capsule to be pathogenic?

Answer 14

• Streptococcus pyogenes*
• Streptococcus pneumonia*
• Yersinia pestis*
• Bacillus anthracis*
• Neisseria meningitidis*

Question 15

Types of flagella systems?

Answer 15

Peritrichious

Lophotrichous

Monotrichious

Question 16

What do archaea have that is like a flagellum?

Answer 16

Archaellum

different evolution

Question 17

Describe peritrichous flagella?

Answer 17

Randomly distributed around the body

bundle together when swimming forward

Question 18

Describe lophotrichous flagella?

Answer 18

Only at ends of cell

Question 19

Describe monotrichous?

Answer 19

Single flagellum

Question 20

What is the flagellar motor evolved from?

Answer 20

Type III Secretion system

Question 21

Where does the energy come from to power the flagella?

Answer 21

PMF

Question 22

How long are flagella?

Answer 22

~10-15 microns long

Question 23

What are flagella made up of?

Answer 23

FliC proteins ~20 K subunits

Question 24

Where are flagella in spirochetes?

Answer 24

In the periplasm, gives the bacteria a corkscrew shape

Whole corkscrew bacteria turns to propel it forward

Question 25

Example of a Spirochete bacteria?

Answer 25

Lyme disease- *Borrelia burgdorferi*

Question 26

What are pili and fimbria used for?

Answer 26

Adherence and twitching motion