Metaphase of mitosis. Chromosomes, attached to the kinetochore microtubules, align in a single plane midway between the spindle poles. The kinetochore microtubules exert tension on the chromosomes, which move back and forth in rapid erratic motion which results in the separation of the daughter chromatids.
Clathrin is a membrane protein that aggregates into a polyhedral cage. This action pulls the cell membrane into droplets or vesicles, which are full of protein or neurotransmitter. Clathrin is essential for exo and endocytosis, and for internal transport between the endoplasmic reticulum and golgi body.
Amoebas are primitive organisms characterized by their flowing movements, extending cytoplasm outward to form pseudopodia; this type of movement is considered to be the most primitive form of animal locomotion. Pseudopodia are also used for feeding. In response to chemical stimuli from smaller organisms, pseudopodia are induced to envelop the organism, at the same time forming a vacuole. Digestive enzymes are secreted into the cavity and the nutrients diffuse from the vacuole into the cytoplasm. Undigested food and wastes are eliminated through the ectoplasm. The ectoplasm also performs respiration, absorbing oxygen from the water and eliminating carbon dioxide.