Flagella

Flagella are whip-like appendages that protrude from the surface of certain types of cells, and are used for locomotion. They are found in both prokaryotic and eukaryotic cells, but there are differences in their structure and function between the two types of cells.

Prokaryotic Flagella

In prokaryotic cells, such as bacteria, flagella are long, helical structures made of a protein called flagellin. These flagella rotate like propellers, allowing the bacteria to move through liquid environments. The movement of prokaryotic flagella is powered by a motor complex embedded in the cell membrane, which uses the flow of ions to generate rotational motion.

Eukaryotic Flagella

In eukaryotic cells, flagella are structurally more complex and are composed of microtubules arranged in a "9+2" pattern. They are found in single-celled organisms such as protists, as well as in specialized cells in multicellular organisms, such as sperm cells. Eukaryotic flagella exhibit a whip-like motion that propels the cell through its environment. The movement of eukaryotic flagella is powered by energy derived from ATP.

Functions of Flagella

Flagella serve several important functions in cells:

• Locomotion: The primary function of flagella is to enable cells to move through liquid environments, allowing them to seek out nutrients, escape from predators, or navigate towards favorable conditions.
• Sensory Functions: In some cells, flagella can also serve as sensory organelles, detecting changes in the external environment and relaying this information to the cell.

Study Guide

To study the topic of flagella, it is important to understand the structure, function, and significance of flagella in both prokaryotic and eukaryotic cells. Here are some key points to focus on:

1. Compare and contrast the structure of prokaryotic and eukaryotic flagella.
2. Describe the mechanism of flagellar movement in both prokaryotic and eukaryotic cells.
3. Explain the importance of flagella in the locomotion and sensory functions of cells.
4. Discuss the evolutionary significance of flagella in different types of organisms.

Additionally, it may be helpful to explore specific examples of cells and organisms that rely on flagella for their survival and reproduction, and to understand the role of flagella in pathogenic bacteria and disease.