BIO 181 Test Bank 1 Short answer essay:

1)Pancake-shaped cells explores the environment – moving filopodia with receptors extend from cell surface all over cell and “sense” environment. (1 point) 2) Then in some area filopodia stop moving due to signal received (biochemical cascade changes cell in that area). (1 point) 3) That area restructures to extend large, lamellipodium that pushes out against the plasma membrane; the mechanism causing this is a new network of actin filaments. (1 point) 4) When lamellipodium touches substrate cell-equivalent of super glue/adhesion plaque holds substrate. (1 point) 5) Cell equivalent of a muscle (i.e. actin and myosin) assembles and attaches to adhesion plaque and extends towards nucleus. (1 point) 6) The muscle contracts pulling the back end of the cell forward. (1 point) 7) The above process repeats itself as cell walks directionally. The students must mention that the process repeats (ie you can’t tell if a person is walking if they just stick out their left leg.) (1 point) 8) Once directionally moving, cell has front and back end with lamellipodia at front end, nucleus towards back end of cell, and retraction fiber at rear of cell. (1 point) 9) Retraction fiber contains cell-equivalent of super glue/adhesion plaque, thinly stretched (like