Protists Overview

Key structural components/biology of the organism – Chris

  • Protist are eukaryotic cells. This means they have a nucleus and other membrane-bound organelles. Protist cells are very unique because all are distinct and different from each other. Protist also have their own kingdom which is called the Kingdom Protist.
  • Most Protist cells are unicellular which means that they are one celled eukaryotes.  Very few Protist cells are multicellular which means that they have many cells within. An example of a multicellular Protist cell is Kelp. Kelp can grow up to 100 meters in an aquatic environment. Multicellular and Unicellular do not show cellular specialization or differentiation in the tissues of the cell. Most Protist cells appear to look the same and function the same but are all unique and different than one another. Protist are able to be parasites and prefer either aquatic or moist environments. Most Protist also have mitochondria in their structure.
  • Protist can be classified in 3 different ways. Protist can be classified as animals cells. This means that they are able to move. Protist can be classified as plant cells. This means that the plant has autotrophs that photosynthesize. Protist can be classified as Fungi cells. Fungi are heterotrophs which means it has cells with cells walls that are able to reproduce. Protist are eukaryotic but are not able to be classified as an animal, plant, or fungi cells. Protist has a very simple cell structure but use the classification of plant, animal, and fungi  to help show the characteristics of the cell.
  • There are many different types of Protist but I will highlight the most common Protist. Protist are able to move three different ways. Protist are able to use there cilia. The cilia use microscopic hair called cilia to move. The tiny hairs flap together to help move. Protist are able to use there flagella which is a long tail that moves back and forth helping to propel the cell forward. Protist are able to use there Pseudopodia which extends part of its cell body to scoot or ooze along.
  • The Protist are able to eat by gathering energy in different ways. They eat food and digest it internally or digest the food outside of their body by secreting enzymes. They are also are able to eat pre digested food. They are also able to get energy from photosynthesis which absorbs sunlight and uses the absorbed energy to make glucose.

 

 

 

Mechanisms of pathogenesis (how does it cause disease) – Shea

 

While each protists method of pathogenesis is slightly varied, they work in generally in one of two main ways: either using the host for nutrients or attacking the host directly. Giardia protozoa are examples of the first kind of protist. They enter the host through tainted food or drink, usually that has been in contact with fecal matter. It then implants itself in the lining of the stomach and starts syphoning of resources. This can lead to minor irritation, along with diarrhea, which in turn spread the disease even more.

 

Malaria acts quite differently. It enter the blood stream through mosquito bites, and finds it way to the liver where it begins multiplying. After a few weeks, the protist bursts and starts affecting red blood cells. When the cells start to die off, the body is unable to oxygenate its cells. This slowly leads to the death of the cells and eventually if untreated the host.

 

Treatment options and how they relate to the biology of the organism — David

 

Protists can be hard to treat because as eukaryotic cells they share many common pathways and proteins with human cells. As a result, drugs that target protists are not as easy to develop as antibiotics. A variety of drugs are used against protists, including some in which the mechanism by which it acts is not fully understood. Some drugs, such as Quinine, are alkaloids that lead to the protists having too many cytotoxins inside them. Other drugs target specific proteins that are used commonly by protists. One of the most commonly-used drugs to fight African Sleeping Sickness, Pentamidine, is theorized to inhibit cell functions related to nucleic acids.

 

The wide genetic diversity of protists and a lack of knowledge and funding about treatment has resulted in many different drugs becoming available to fight protists. There is no single drug that fights all protists and some protists are developing resistance to the drugs that are widely-used to fight them.

 

Examples of diseases caused by this organism – David

 

The two most common diseases caused by protists are Malaria, caused by protists of the genus Plasmodium, and African Sleeping Sickness, caused by the protists Trypanosoma brucei gambiense or Trypanosoma brucei rhodesiense.

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