What are the visible structures that is present in protist cell which is not present in animal and plant cell?

Answer 1

Protists are a very diverse group and may contain a combination of these structures as well as those shared by plants, animals, and fungi.

-Contractile vacuoles, like those found in protozoa, are structures that gather water and then squeeze it out of the cell to maintain the proper osmotic balance. Found in single-celled freshwater protists.

-Cysts are protective coatings made by some protozoa when conditions are unfavorable (usually due to a lack of food or water).

-If the protist has a protective/supportive structure (pellicle) it will often have specialized sections for food intake: cytostomes are openings in the covering that act as a mouth to allow food to enter and anal pores are sites for excretion of waste.

-An Oral groove is an indentation in the cell structure that directs the floating food particles into the gullet. At the end of the gullet is the cytostome where food is packaged into food vacuoles.

-Many protists have a macronucleus and micronucleus. The macronucleus is the larger nuclei and controls all the cell functions except reproduction (vegetative function). The micronucleus is the smaller nuclei and controls the cell's reproduction (generative function).

-Glycosomes are membrane-enclosed organelles found in a few pathogenic species of protozoa. These organelles contain glycolytic enzymes (proteins that breakdown glucose). It is most recognizable in the human pathogenic trypanosomes (like those responsible for sleeping sickness).

-An Eyespot apparatus (also called Stigma) is an organelle that can detect light, its intensity and its direction. It can be found in some motile species of green anlgae and other photosynthetic single-celled organisms (like euglenids). Using this organ the organism can respond by postitive phototaxis (swimming towards the light) or negative phototaxis (swimming away from the light).