Table of Contents
What are the four types of flagellar arrangement?
Based on their arrangement, bacteria are classified into four groups: monotrichous (having one flagellum), amphitrichous (single flagellum at both ends), lophotrichous (numerous flagella as a tuft), and peritrichous (flagella distributed all over the cell except at the poles).
What is flagellar filament?
The bacterial flagellar filament is a helical propeller for bacterial locomotion. It is a helical assembly of a single protein, flagellin, and its tubular structure is formed by 11 protofilaments in two distinct conformations, L- and R-type, for supercoiling.
What are the 3 types of flagella?
The three types of flagella are bacterial, archaeal, and eukaryotic. The flagella in eukaryotes have dynein and microtubules that move with a bending mechanism. Bacteria and archaea do not have dynein or microtubules in their flagella, and they move using a rotary mechanism.
What type of flagella arrangement is present in spirochetes?
Spirochetes, which are members of a group of gram-negative bacteria with a spiral or flat-wave cell body, also show flagella-dependent motility, but their flagella are hidden within the periplasmic space and are thus called periplasmic flagella (PFs).
What is a single flagellum?
A single flagellum can extend from one end of the cell – if so, the bacterium is said to be monotrichous. 2. A single flagellum (or multiple flagella; see below) can extend from both ends of the cell – amphitrichous. 3.
What are bacteria with a single flagellum called?
Monotrichous bacteria have a single flagellum (e.g., Vibrio cholerae).
How do bacteria move with flagella?
Flagella propel bacteria through the body The rotation of the filament allows bacteria to move around in their environment. The motor embedded in the bacterial cell membrane rotates—just as a car motor spins beneath the hood of the vehicle—to drive the movement of the filament outside.
What is the function of hook in flagella?
The hook acts as a universal joint that connects the flagellar basal body and filament, and smoothly transmits torque generated by the rotary motor to the helical filament propeller.
Can flagella be seen with a light microscope?
The basic point about the flagella stain is that the combination of chemicals produces a thickened coat around the flagella, making them more easily seen with a light microscope. Flagella are extremely thin and of small diameter, so they are below the resolution of the light microscope if unstained.
What is the unique feature of the flagella of spirochetes?
Spirochetes are unique in that they have endocellular flagella (axial fibrils, or axial filaments), which number between 2 and more than 100 per organism, depending upon the species. Each axial fibril attaches at an opposite end and winds around the cell body, which is enclosed by an envelope.
How many chains of flagellin molecules are there in a filament of bacterial flagellum?
Filament Structure The flagellar filament is composed of 11 strands of protofilaments, which are nearly longitudinal arrays of subunits (Fig. 3). The densely packed central core of filament consists of a concentric double tubular structure made of domains D0 and D1.
What term best describes a microbial cell with a single flagellum at one end?
What term best describes a microbial cell with a single flagellum at one end? Monotrichous.
What is flagellar motility?
Abstract. The bacterial flagellum is a helical filamentous organelle responsible for motility. In bacterial species possessing flagella at the cell exterior, the long helical flagellar filament acts as a molecular screw to generate thrust.
What is the function of hook in bacteria?
The hook is made of about 120 copies of a single protein, FlgE, and its function as a nano-sized universal joint is essential for dynamic and efficient bacterial motility and taxis. It transmits the motor torque to the helical propeller over a wide range of its orientation for swimming and tumbling.
What is the basic structure of flagellum?
The flagellum is a supramolecular structure composed of about 20 protein components and divided into three substructures: the filament, the hook and the basal body. The filament is a helix, which takes on several distinct forms under various conditions.
How is the diameter of flagella increased so that one may observe it under a light microscope?
Why is it impossible to observe a flagellum using the bright field microscope?
Bacterial flagella are normally too thin to be seen under such conditions. The flagella stains employs a mordant to coat the flagella with stain until they are thick enough to be seen. These staining techniques are typically very difficult.
What structure is responsible for motility in spirochetes?
The periplasmic flagellum, which rotates between the outer membrane and peptidoglycan layer, is responsible for spirochete motility (1, 2).
Which of the following are characteristics of spirochetes?
Spirochetes are gram-negative, motile, spiral bacteria, from 3 to 500 m (1 m = 0.001 mm) long. Spirochetes are unique in that they have endocellular flagella (axial fibrils, or axial filaments), which number between 2 and more than 100 per organism, depending upon the species.