Examination of Protozoan Cultures to Determine Cellular Structure and Motion Pattern Abstract
Protozoans are unicellular eukaryotes with either plant- or animal-like characteristics. Through careful observation, we analyzed various protozoan cultures in order to identify characteristics associated with cell structure and movement of these one-celled organisms. We found that Protists exhibit certain characteristics that allow them to be categorized into different groups, mainly determined by their locomotion patterns. Despite differences in locomotion and the varying plant-like and animal-like organelles, all protists share key characteristics and functions that allow them to feed, grow, and reproduce--processes essential for survival and common to complex organisms. Introduction
Unicellular eukaryotes belong to the kingdom Protista, and are often referred to as “protists” or “protozoans.” The name “protozoan” means “first animal,” but eukaryotes may display either plant or animal-like characteristics, or a combination of both. Although unicellular, they have a nucleus and membrane-bound organelles, making them functionally complex despite their small size. Each small protist is a self-supporting unit, carrying out all the processes for survival in just one cell. They thrive on moisture and can be found on moist soil and in fresh and marine bodies of water. There are about 30,000 known species of protozoans, commonly classified according to their movement patterns as sarcodines—moving with false feet called pseudopodia or, flagellates—moving with whip-like structures known as flagella, ciliates—moving with short hairs known as cilia, and sporozoans—with no movement. They all have varying shapes, sizes, and survival strategies. For example, some may “hunt” small particles of food such as bacteria or algae; whereas others may be parasitic, inhabiting larger organisms. Despite their differences, all protists have several characteristics in common. In addition to a nucleus or nuclei to house their genetic material, most protists have mitochondria for metabolic functions, and vacuoles for digestion and excretion. With the help of these and other cellular structures, protists may feed, grow, and reproduce. In this lab we observed select examples of protists in order to identify their cellular structures, and determine to which group of protista they belong based on their form of movement. We also made drawings of our observations using light and dissection microscopes to practice proper microscopy skills, including making wet-mount slides and cell sizing. By observing, drawing, and classifying protista, we learned about the cell structure and movement patterns of these one-celled organisms. We also learned about the differences and similarities of various protist cells . Since we will observe how protists move, it will be interesting to figure out patterns of locomotion. For example, what happens when the protist encounters an obstacle? Does motion change when the organism is feeding? How does motion relate to where the organism lives? What characteristics do the protists exhibit: plant, animal, or both? Do the plant/animal characteristics influence motion patterns?
Three protists were chosen for observation. See the list of protists below to choose three samples. For each of the protists, a pipette was used to extract a few drops of culture from the culture jar. The drops of culture were placed on a clean microscope slide and covered with a slide cover slip. Using a light microscope, each protist was examined at different magnifications until the best field of view was found for identifying cellular structures. The color, shape, and motion cellular structures was noted. Each of the protists was drawn and the drawings were labeled. Field-of-view, magnification, and cell size was noted on the drawings, along with the organism’s name and protist group. Protists...