How do Protists Eat?

Vocabulary  Autotrophs: An organism that can produce its own food using, light, water, carbon dioxide or other chemicals.  Heterotrophs: An organism that must eat to obtain energy  Food Vacuole: Food vacuoles are essentially a circular portion of the plasma membrane that encircles food particles when they enter the cell. Once inside, the food vacuoles are the mechanism by which a cell eats, so the food particles can be used as energy  Oral groove: canal of some protists used to ingest nutrients (protists version of a mouth)  Gullet: Throat or Pharynx  Food vacuole: a membrane enclosed cell vacuole with a digestive function, containing material taken up in by the process of phagocytosis.  Anal pore: An opening where waste is expelled.  Phagocytosis: The process by which a cell engulfs a solid particle to form an internal vesicle known as a food vacuole.  Photosynthesis: The process that converts light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms' activities.

Different ways protists gather food. Different protists gather energy in different ways.  Some eat food and digest it internally.  Others digest their food outside of their bodies by secreting enzymes. Then they eat the pre-digested food.  Some protists use photosynthesis like plants. They absorb sunlight and use this energy to make glucose.

Amoebas  Heterotrophs: must ingest their food  Amoebas are shapeless and eat by engulfing their food with their bodies.

Amoeba eating

Paramecium  Are heterotrophs  Paramecium feed on microorganisms like bacteria, algae, and yeasts.  The paramecium uses its cilia to sweep the food along with some water into the cell mouth after it falls into the oral groove. The food goes through the cell mouth into the gullet.  When there is enough food in it so that it has reached a certain size it breaks away and forms a food vacuole. The food vacuole travels through the cell, through the back end first. As it moves along enzymes from the cytoplasm enter the vacuole and digest it.  The digested food then goes into the cytoplasm and the vacuole gets smaller and smaller. When the vacuole reaches the anal pore the remaining undigested waste is removed.  Their common form of prey is bacteria. A single organism has the ability to eat 5,000 bacteria a day.

Paramecium Feeds

How does a Euglena Eat?  Autotrophic and Heterotrophic  When acting as an autotroph the Euglena utilizes its red eyespot to locate light. Without light, it cannot use its chloroplasts (green parts inside the body) to produce sugars by photosynthesis.  Algae is a source of chloroplasts.  When Euglena do not have enough light to make its own food, it looks for other things to eat. Swimming around, it preys on other tiny organisms, such as amoeba and paramecium.  Engulfing the food through its cell membrane Euglenas take food in through its gullet and deposits it into a food vacuole.  Many Euglena are considered mixotrophs: autotrophs in the light and heterotrophs in the dark.

Volvox  This organism uses its red eyespot to find sunlight.  Volvox then converts the sunlight into energy through photosynthesis.  In addition, its diet consists primarily of other algae. On occasion, the volvox may consume other types of plants as well.  The organism mainly finds its food by rummaging through the water using its flagella to hunt down food sources.

How do Protists Reproduce?

How does an Amoeba reproduce?  Amoebas reproduce (make more amoebas) by a process called binary fission. This means that one amoeba can split in half and make two identical new amoebas.  This is asexual reproduction.

Amoeba Reproducing

 HOW DO PARAMECIUM REPRODUCE?  Paramecium are capable of both sexual and asexual reproduction. Asexual reproduction is the most common, and this is accomplished by the organism dividing transversely. The macronucleus elongates and splits. Under ideal conditions, Paramecium can reproduce asexually two or three times a day. Normally, Paramecium only reproduce sexually under stressful conditions. This occurs via gamete agglutination and fusion. Two Paramecium join together and their respective micronuclei undergo meiosis. Three of the resulting nuceli disintegrate, the fourth undergoes mitosis. Daughter nuclei fuse and the cells separate. The old macronucleus disintegrates and a new one is formed. This process is usually followed by asexual reproduction.

How the Paramecium Reproduces Paramecium are capable of both sexual and asexual reproduction. Paramecium can reproduce asexually two or three times a day. Paramecium only reproduce sexually under stressful conditions.

The Euglena Reproduces In order for Euglena to make more Euglena, it will complete a process called mitosis. That means it can split itself in half and become two Euglena. It is asexual. It can only do this if it is well-fed and if the temperature is right. Euglena can reproduce better in warm temperatures.

How does the Volvox reproduce? Volvox cell reproduces asexually as well as sexually.