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An overview of the protists kingdom, which consists of unicellular and multicellular life forms that have a nucleus. Protists are more complex than archeabacteria and eubacteria due to their nucleus. They can be found in various environments and come in different shapes, sizes, and colors, some resembling animals, plants, or fungi. Protists obtain energy through various means, such as photosynthesis or consuming food. They reproduce asexually or sexually, and have adapted to their environments through various mechanisms.
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The Protists Kingdom consists of unicellular (life forms with only one cell) and some multicellular life forms that have a nucleus. If you think back to everything we discussed in class that would make Protists eukaryotic cells. The main difference between protists and prokaryotes (archeabacteria and eubacteria) is that Protists are more complex, having a nucleus.
Protists are all around us. There are more than 200,000 species in the kingdom. Protists can be found in most every environment on Earth. They have been discovered in the deepest parts of the oceans and on the highest peaks of the mountains. Ponds, streams, rivers, swamps, most soil, and even the very acidic water caused by industrial pollution contain some species of Protists. As long as there is a consistent supply of water Protists can flourish.
Protists come in many different shapes, sizes, and colors. Some Protists have traits like animals. Others have traits like plants, such as Algae. Still others have traits like fungi. Slime molds, water molds, and downy mildews are examples of fungi-like Protists. In early classifications, some Protists were grouped in the animal kingdom, and the algae and slime molds were placed among several divisions of plants. Today scientists classify these tiny organisms in their own kingdom known as Protista.
Even though scientists have gone to great lengths to note the differences between Protists and the animal and plant kingdoms, they still use these kingdoms to help describe the different types of Protists. Protists are animal like, plant like, or fungi like.
Protists are so small that they do not need any special organelles to take in gas or get rid of waste. They rely on simple diffusion, the movement of materials from an area of high concentration to an area of low concentration. Diffusion only works if you’re really small, so most Protists are limited to being small single cells. Plus if they are too large their cilia or flagella will not have enough power to move them out of the way of danger.
Just like bacteria, Protists can gain energy in a variety of ways. Some Protists are Heterotrophs, which means they get energy by eating or absorbing food. Examples of hertertrophs are Amoebas and Paramecium (animal like Protists) that move around to get their food. Other Protists are Photoautotrophs that make their own food from the sunlight. Algea is a great example of a photautotroph. Unlike the bacteria kingdoms scientists do not know of any Protists that are Chemoautotrophs.
The photoautotrophs are very similar to plants. They have chloroplasts that are responsible for absorbing the sunlight and turning it into useable energy. As for the heterotrophs, these Protists eat by engulfing their food in their cell membrane. The cell membrane surrounds the food and then pinches off a section of membrane to form a hollow space inside the cell.
This hollow space that is surrounded by the cell membrane is called a vacuole. Just like in plant and animal cells the vacuole in the Protists also stores water and waste. Paramecium and many other Protists also have a vacuole similar to a lysosome, which gets rid of waste products and pushes them outside the cell.
As we discussed in class most Protists move by using flagella (tails) or cilia (tiny hairs). Some Protists just blob from one area to the next. (Poor amoeba has no feet to move). They only have false feet (Pseudopods) to wrap around their food or to move from one area to the next.
Protists reproduce asexually through binary fission while a few species are capable of sexual reproduction (2 parents). Animal like amoebas and plant like Euglena reproduce asexually meaning the only have binary fission. In this case, when the parent cell splits in half, there is an exact chromosome copy in each daughter cell.