Lab 11 Bacterial Motility

Question 1

What are the mechanisms that allow for bacterial motility?

Answer 1

twitching
gliding
flagella
axil filaments

Question 2

What 2 motility mechanisms help move across a solid surface?

Answer 2

• twitching

- gliding

Question 3

What mechanisms helps bacteria move through a liquid environment?

Answer 3

• flagella

- axial filaments

Question 4

Describe how a bacterial cell twitches?

Answer 4

• bacterial cells use structures on their surface called pili to attach to a solid surface
• allow for directional movement
• ex. P. aeruginosa

Question 5

Describe how a bacterial cell glides

Answer 5

• similar to twitching motility; cells move slowly across a solid surface
• not dependent on pili
• allow for directional movement
• ex. flavobacterium psychrophilum

Question 6

What are the 3 main parts of a flagella?

Answer 6

• basal body
• hook
• filament

Question 7

What is the basal body (of the filament)?

Answer 7

set of proteins embedded in the cell wall and plasma membrane of bacterial cells

Question 8

What is the function of the proteins in the basal body?

Answer 8

-act as a motor and rotates when energy is applied.

Question 9

What is the energy source of the basal body? explain

Answer 9

• Proton motive force; H+ ions are pumped out of the cell by metabolic processes such as the breakdown of sugars by fermentation or cel respiration
• has both a concentration and electrical component

Question 10

What is the basal body connected to? Explain its structure/function

Answer 10

The hook; thick and short projection from a cell’s surface and behaves as a hinge or pivot point.

Question 11

What is the hook of the basal body connected too?

Answer 11

filament

Question 12

what makes up the majority of the structure of the flagellum?

Answer 12

filament

Question 13

Define chemotaxis

Answer 13

what any type of cell exhibits any type of motility in response to a chemical concentration gradient

Question 14

Functions of a run and tumble chemotaxis

Answer 14

• ‘biased, random walk’
• bacteria rotate all their basal bodies in one direction
• during a run, the bacterial cell uses its membrane receptors to detect whether the nutrients are increasing in concentration or decreasing
• larger concentration= longer run
• smaller concentration=shorter run and tumble

Question 15

What direction do the basal bodies turn for a cell to run

Answer 15

counter clockwise; moves towards attractant

Question 16

What direction do the basal bodies turn for a cell to tumble?

Answer 16

clockwise; stops forward motion and cell tumbles and changes direction