Lecture 1B: Cell Locomotion Flashcards
What allows prokaryotic cells to move in their environments?
Motility devices that allow them to swim or crawl
What are the two major types of prokaryotic cell movement? (2)
Swimming and gliding
What is the phenomenon called when motile cells move toward or away from stimuli?
Taxis
What structure do many Bacteria use for swimming motility?
Flagellum
What is the analogous structure to flagella found in many Archaea?
Archaellum (pl. archaella)
- Tiny rotating machines that push or pull the cell through a liquid
- long, thin, appendages
flagella
What is the typical width of the appendages of bacterial flagella?
15–20 nm
How can flagella be observed under a microscope? (2)
- light microscopy
- electron microscopy
Different arrangements of flagella (4)
- polar
- lophotrichous
- amphitrichous
- peritrichous
Flagella are attached at one or both ends of a cell.
flagellation
polar flagellation
What is a group of many flagella (tuft) called?
flagellation
Lophotrichous flagellation
Tufts of flagella emerge from both poles of the cell
flagellation
amphitrichous flagellation
flagella located inserted around the cell surface
flagellation
peritrichous flagellation
The strength of the proton motive force affects the __ of flagella.
rotational speed
What is the maximum rotational speed of flagella?
Up to 1000 revolutions per second
What swimming speed can bacteria achieve relative to their size?
Up to 60 cell-lengths/sec
How do the swimming motions of peritrichously flagellated organisms differ from polarly flagellated organisms?
- Peritrichously flagellated organisms move slowly in a straight line
- Polarly flagellated organisms move more rapidly and continuously
True or False: Flagella rotate at a constant speed.
False
What is the significance of motility for prokaryotic cells?
Allows cells to reach different parts of their environment for resources or protection.
Flagellar structure and activity:
- __ in shape
- consists of several components
- filament composed of __
- __ rotating machine
- helical
- flagellin
- reversible
What is the main part of the bacterial flagellum called?
Filament
The filament is composed of many copies of a protein called flagellin.
What protein is the filament of the bacterial flagellum primarily composed of?
Flagellin
The amino acid sequence of flagellin is highly conserved in Bacteria.
What does the hook connect in the structure of the flagellum?
The filament to the flagellum motor in the basal body
The hook consists of a single type of protein.
In bacterial flagella, which rings are found in the basal body? (4)
L ring, P ring, MS ring, C ring
The L ring is embedded in the LPS, P ring in peptidoglycan, MS ring in the cytoplasmic membrane, and C ring in the cytoplasm.