Flagella Flashcards
Describe the structure and function of fimbriae.
Fimbriae are slender tubes composed of helically arranged protein subunits Willey, et al., 2011, pp.74).
They are 3-10nm in diameter (Willey, et al., 2011, pp.74).
A cell has up to 1000 fimbriae (Willey, et al., 2011, pp.74).
Their function is to attach the cell to solid surfaces (Willey, et al., 2011, pp.74).
Type IV pili are involved in motility and DNA uptake during bacterial transformation (Willey, et al., 2011, pp.74).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe the structure and function of sex pili.
Sex pili are hair-like structures genetically determined by conjugative plasmids (Willey, et al., 2011, pp.74).
They are 9-10nm in diameter (Willey, et al., 2011, pp.74).
Cells have up to ten sex pili (Willey, et al., 2011, pp.74).
They are involved in cell to cell attachment during conjugation and facilitate gene transfer (Willey, et al., 2011, pp.74).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe the different types of flagella distribution.
Monotrichous bacteria only have one flagella (Willey, et al., 2011, pp.74-75).
Amphitrichous bacteria have a single flagellum at each pole (Willey, et al., 2011, pp.74-75).
Lophotrichous bacteria have a cluster of flagella at one or both ends (Willey, et al., 2011, pp.74-75).
Peritrichous bacteria have flagella spread evenly over the whole surface (Willey, et al., 2011, pp.74-75).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe flagella synthesis.
Twenty to thirty genes are involved in flagella synthesis (Willey, et al., 2011, pp.75).
They code for the flagellin protein and the hook and basal body proteins (Willey, et al., 2011, pp.75).
They also control flagella construction and function (Willey, et al., 2011, pp.75).
A type III-like secretion process transports flagellin subunits through the filaments internal core (Willey, et al., 2011, pp.75).
The filament cap causes subunits to spontaneously aggregate at the tip (Willey, et al., 2011, pp75).
Thus, the filament grows at the tip, not at the base (Willey, et al., 2011, pp.75).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe the type III-like secretion system.
The type III-like secretion system is a protein secretion system in gram negative bacteria (Willey, et al., 2011, pp.75).
It has a needle-like structure through which proteins are secreted (Willy, et al., 2011, pp.75).
It is analogous to the filament of flagellum (Willey, et al., 2011, pp.75).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe how the proton motive force acts as the power source of the motor in flagella.
The proton motive force (PMF) is needed to generate torque and cause flagella rotation (Willey, et al., 2011, pp.77-78).
It is created by metabolic activities such as the electron transport chain (Willey, et al., 2011, pp.77-78).
First, MotA and MotB form a channel which allows proton movement from outside to inside the plasma membrane (Willey, et al., 2011, pp.77-78).
Protons move down the pH and charge gradient (Willey, et al., 2011, pp.77-78).
The proton movement releases energy which is used to move the flagellum (Willey, et al., 2011, pp.77-78).
The speed of flagella rotation is proportional to the magnitude of PMF (Willey, et al., 2011, pp.77-78).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe chemotaxis.
Chemotaxis describes the movement of bacteria either toward chemical attractants or away from chemical repellents (Willey, et al., 2011, pp.79-80).
The attracts and repellents are detected by chemoreceptors (Willey, et al., 2011, pp.79-80).
While going towards the attractant or away from the repellent, bacteria tumble less frequently (or have longer runs) (Willey, et al., 2011, pp.79-80).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe twitching motility.
Twitching motility is when bacteria moves in short, intermittent jerky motions (Willey, et al., 2011, pp.78-79).
It only occurs when cells are in contact with each other (Willey, et al., 2011, pp.78-79).
Pili (such as type IV pili) extend and retract (Willey, et al., 2011, pp.78-79).
The extended pilus contacts the surface at a distance from the cell body (Willey, et al., 2011, pp.78-79).
The pilus then retracts and pulls the cell forward (Willey, et al, 2011, pp.78-79).
The extension or retraction process is powered by ATP hydrolysis (Willey, et al., 2011, pp.78-79).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
