Eukaryotic single cell movement
Both single cell life forms as well as multicellular life forms are exist in eukaryotes. According to the life form they adopt their own mode of locomotion.
Protozoan are single cell eukaryotes. Theyare following different type of locomotion according their life form. Amoeba is a single cell protozoa. It can migrate with the help of pseudopodia and this movement is called as amoeboid movement. Most of the time amoeba move to get the food. Various hypotheses regarding the amoeba movement:front contraction hypothesis, tail contraction hypothesis, ectoplasmic contraction theory, cytoplasmic streaming, sol-gel theory, etc., Here we discuss the simple ameboidal locomotive sol-gel theory.
The simple mechanism of amoeba movement (Figure 14.4) as follows

1. Swelling of the plasmagel results pseudopodia in response of semipermeable membrane turgidity.
2. Movement of plasmasol towards the pseudopodia with simultaneous contraction of plasmagel
3. Gelation of plasmosol results enlargement of pseudopodia
4. Adhesion to the food particle.

Figure 14.4 : Sol-Gel Ameoba movement