Question

The following four events occur during cell locomotion: Place them in the correct order.

1. The cell breaks its rear contacts with the substratum, retracting its trailing edge.
2. A part of the cell surface protrudes in the direction of cell movement.
3. Lower surface of cell protrusion attaches to substratum, forming temporary anchorage sites.
4. The bulk of the cell is pulled forward over adhesive contacts.
1) 1-2-3-4
2) 2-3-1-4
3) 2-3-4-1
4) 1-4-2-3
5) 4-2-3-1

Answer 1

The correct sequence of events during cell locomotion is 2-3-4-1, which describes the progression from the protrusion of the cell membrane to the retraction of the trailing edge.

Step-by-step explanation:

The correct order of events during cell locomotion is initiated by a part of the cell surface protruding in the direction of cell movement, which is the formation of a lamellipodium. This protrusion occurs due to the rapid polymerization of actin filaments. Next, the lower surface of this protrusion attaches to the substratum, forming temporary adhesion sites. The bulk of the cell then pulls forward over these adhesive contacts, utilizing the forces generated by actomyosin contractions. Finally, the cell breaks its rear contacts with the substratum by retracting its trailing edge as the actin filaments depolymerize. Therefore, the correct sequence is: 2-3-4-1.