Unicellular Eukaryotes Observation Essay

There are several experiments that must be conducted before a species can be identified. The tissue samples of these organisms must be obtained, and their tissues must

The trophozoite of N fowleri consists of an amoeba surrounded by a two-layer membrane. The cytoplasm contains free and bound ribosomes, as well as membrane-bound organelles. A smooth endoplasmic reticulum, a Golgi-like structure, mitochondria, vacuoles, and nucleus-containing nuclear envelope are present. Microfilaments create a supportive cytoskeleton. The N fowleri flagellate is pear-shaped. The cytoplasm has fewer vacuoles, and the components of a flagellar apparatus (flagellum, basal body, rootlet) are present. The spherical cyst is enclosed in a mucous-sealed porous cell wall. The cytoplasm contains enlarged mitochondria and the nucleolus is less pronounced.

Prokaryotes were defined in 1962 by Stanier and van Niel as “anucleate cells, without membrane enclosed organelles of respiration or photosynthesis, divided by fission not mitosis, and used peptidoglycan to strengthen their walls” (Mayr, 1998). This definition and the creation of the prokaryote/eukaryote dichotomy served to highlight the diversity and significance of the single-celled organisms previously labelled ‘Monera’ and relegated to the same kingdom status as the distinct groups of plants animals and fungi (Sapp, 2009; Woese, Kandler and

Euglena are unicellular protists, which are organisms made of one cell that is not an animal, plant or fungus. Most have both plant and animal characteristics. For example, they often have a flagellum, which is a characteristic of animal cells, for motility and chloroplasts, which are characteristics of plant cells. They are pear shaped with a flagellum, which looks like a tail.

Figure 1: Represents the mixture of Euglena culture, and the percentage of rounded cells noted at an increasing light intensity. Rounded cells in this experiment were identified as pear shaped.

4. The structure of these first eukaryotic cells was so versatile that eukaryotic microorganisms soon spread out into available habitats and

Cell is a wide type of substance that have variations between species and species, for example a plant cell contains a cell wall which is absent in most animal cells. Scientists had been trying to classify all organisms into different groups. Current classification system is the three domains and six kingdoms which the three domain divides organisms based on the ribosomal RNA they contained in the cells. The three domains are Bacteria, Archaea and Eukarya which the first two are made up of prokaryotic cells and Eukarya is made up of eukaryotic cells. This essay will focus on the differences between eukaryotic and prokaryotic cells.

One of the structures of prokatyotic cells are Flagella. They are genetically unique and are used as a point of identification of bacterium. Flagella are structures attached to the cell surface for most motile bacteria and are composed of protein. A bacterium can detect the quality and quantity of certain chemicals in its environment and either swim towards or away from it if nourishment or threat is detected, as the case may be. This has been seen as evidence of the ecological survival advantage of bacterial and other prokaryotes (Structure and Function of Bacterial Cells. n.d.)

In order to identify the three specimens, I would look for these following characteristics of each organism:

Euglena is part of the Euglenozoa clade and have animal and plant characteristics. The ability for Euglena to be able to interchange from being an autotroph and a heterotroph is referred to as being mixotropic. This genus exhibits all of the unique characteristics of the Euglenozoa clade such as: being unicellular and having flagella and chloroplasts. The flagella are located on the anterior of this organism, and are used for locomotion and heterotrophic feeding by engulfing their prey via phagocytosis. The chloroplast contains chlorophyll and is the site of photosynthesis, which helps the organism with autotrophic feeding. Euglena is photosynthetic and exhibits positive phototaxis behavior because they move towards light rather than away

Ciliates are a group of protists characterized by the presence of hair-like projections called cilia that help in locomotion, attachment, feeding, and sensation. Till date around 3,500 ciliates species have been described globally. Ciliates need extra attention as their extant species number is estimated to be around 30,000, making it one of the most diverse groups. They range in size from 10 µm - 4 mm in length and inhabit wide variety of ecological niches; free living forms to parasitic and symbiotic forms. Free living forms are found in both aquatic and terrestrial habitats. Aquatic ciliates are reported from oceans, rivers, lakes, glaciers, ponds and even from hot springs suggesting their ability to survive in diversified environments.

Eukaryota is the domain for all organisms that contain a nucleus. It is an extremely diverse and variable domain, which includes thousands of microscopic organisms plus all the large animal and plant species that are found on land and in water.

The class Choanoflagellatea was first described by Henry-James Clark in 1867, and are now considered the sister group to Metazoans, also known as animals (Leadbeater, 2015). Choanoflagellates can be colonial or solitary organisms (Hickman, 2015) and can be found practically anywhere from oceans to even in permafrost (Leadbeater, 2015). They tend to be three to ten μm in size and lack chloroplasts (King, 2005). These organisms have no color to them, consist of one flagellum that they use for swimming and to make water flow toward them for capturing food (Leadbeater, 2015), and appear ovoid in shape. Around the flagellum is a collar of microvilli that are actin-based. This collar is the location where food is ingested into the cell body

They all have a double membrane chloroplasts, but the glaucophytes plastid morphology is unusual because it resembles cyanobacteria, as they still include the outer peptidoglycan layer between the chloroplast envelopes, and also resemble Chlorophyta and Rhodophyta plastid. Both Rhodophyta and Glaucophyta consist of various features that are derived from the cyanobacteria but absent from Chlorophyta. These are phycobilins pigments and phycobilisomes on the surface on thylakoid membranes. Because of sequencing algae chloroplast genomes it is evident that glaucophytes, rhodophytes and chlorophytes have evolved from a second endosymbiotic event, since they are closely related to the ancestral cyanobacteria (Tomitani, 2006).

-Objects smaller than 2.0μm such as viruses must be examined with this type of microscope-resolving power much greater because wavelength of electrons is 100,000 times smaller than the wavelengths of visible light.