Mobility/Movement - SS1 Biology Lesson Note

Mobility is the ability of an organism to move from one location to another for any number of reasons. All organisms that can move are equipped with one or more organelles or mechanisms to facilitate movement.

 

CYCLOSIS

Cyclosis, also known as cytoplasmic streaming, is a biological process observed in plant and animal cells. It involves the movement of cytoplasmic components, such as organelles and nutrients, within the cell's cytoplasm. This movement occurs in a circular or rotational manner along specific paths within the cell.

During cyclosis, cytoplasmic streaming is driven by the coordinated action of molecular motors, including myosin and actin filaments. These motor proteins generate forces that propel cytoplasmic materials along the cytoskeletal network, which consists of microfilaments, microtubules, and intermediate filaments.

Cyclosis serves various functions within cells. It aids in the distribution of organelles and nutrients, ensuring efficient transport to different regions of the cell. It also helps in the exchange of gases and the removal of waste products. Additionally, cyclosis assists in maintaining cellular homeostasis by facilitating the movement of signaling molecules and other essential substances.

Figure 58 image from wikipedia.org

In plant cells, cyclosis is particularly important for the transport of nutrients and organelles within large, multicellular structures like the roots, stems, and leaves. It assists in the movement of chloroplasts within the cell, optimizing their exposure to light for photosynthesis.

Cells use various organelles and structures to facilitate movement. Here are some of the key organelles involved in cell movement:

§  Flagella: Flagella are long, whip-like appendages that protrude from the cell surface. They are primarily found in certain types of single-celled organisms, such as bacteria and eukaryotic protists. Flagella exhibit wave-like movements, propelling the cell through fluid environments.

§  Cilia: Cilia are short, hair-like structures that cover the cell surface. They are found in many types of cells, including epithelial cells lining the respiratory tract and reproductive system. Cilia move in a coordinated manner, creating wave-like motions to move fluid or propel the cell.

§  Pseudopodia: Pseudopodia, meaning "false feet," are temporary extensions of the cell membrane formed by cytoplasmic streaming. They are particularly prominent in amoeboid cells and play a crucial role in cell locomotion. Pseudopodia are formed by the reorganization of the cytoskeleton and allow cells to extend and contract, enabling movement.

Figure 59 image from ck12.org