Lab quiz chapter 26

Protozoans (proto=first, soan=animals) are among the most versatile of all eukaryotes on earth

  • protozoans are eukaryotes with animal-like heterotrophic ecology, meaning they are active consumers and not photosynthetic

  • have food vacuoles

Amoebas (SuperGroup Amoebozoa)

  • found around the world in marine, freshwater, and terrestrial environments.

  • pseudopods- movable extensions of cytoplasm used for locomotion and gathering food

  • polyphyletic, lack flagella, and most reproduce asexually

    Amoeba

  • has a structure and physiology typical of most amoeboid genera

  • are phagocytic- they engulf food particles and form a food vacuole surrounded by a membrane, then secrete enzymes into the food vacuole for intracellular digestion. A contractile vacuole maintains the cell’s water balance by accumulating and expelling excess water

  • other amoebas include Difflugia- which creates a protective case of sand grains called a test

  • test- general term referring to a secreted or partially secreted covering like a shell

  • INSERT IMAGE OF AMOEBA DIAGRAM

Slime Molds (Supergroup Amoebozoa)

  • Physarum is a slime bold that streams along the damp forest floor in a mass of brightly colored protoplasm called plasmodium

  • Plasmodia- coenocytic (multinucleate) because their nuclei are not separated by cell walls, and the entire pasmodium resembles a moving mass of slime

  • the plasmodium may dry into a hard resistant structure called sclerotium and remain dormant until conditions improve, or if light is available, the diploid plasmodium will move to the illuminated area and coalesce

    • the condensed structure will grow sporangia and meoisis will produce spores for dispersal

Formaniniferans (supergroup Rizaria)

  • marine organisms called “shelled amoebas” because they surround themselves with a secreted test and have long, this rather stiff seudopods protruding from their tests.

    • their tests is made of calcium carbonate and is perforated with pores

Flagellates ( Supergroup Excavata)

  • flagellates have at least one flagellum and are likely the most primitive protozoans

  • Flagellates are parasitic as well as free-living heterotrophs

    Trypanosoma

  • trypanosomes are pathogenic and cause African sleeping sickness and chagas disease

  • common in the tropics and spread by infection from biting insects such as mosquitoes, sand flies and tstese flies

African Sleeping sickness

  • Human African trypanosomiasis, is also known as a sleeping sickness and is a bector-borne parasitic disease

  • they are transmitted to humans by the bite of a tsetse file which acquire their infection from humans or other infected animals

Ciliates (Supergoup Chromalevolata)

  • more than 8000 species of ciliates have been described, all having characteristically large numbers of cilla

  • Many ciliates also have two types of nuclei: micronuclei and macronuclei

  • macronuclei develop from micronuclei, control cellular function, and they divide when ciliates reproduce asexually by mitosis

    Paramecium

  • free living fresh water genus that is widely studied and easily observed

  • undergoes a sexual process called conjugation

  • conjugation- when individuals from two different strains align longitudinally and exchange nuclear material

    • the exchange seems to stimulate metabolism of the individuals and is usually followed by frequent mitosis

  • A sexual reproduction is more common than conjugation and includes mitosis of the micronucleus and transverse fission of the macronucleus and cell body

Vorticella and Other Ciliates

  • Vorticella is a freshwater ciliate which is sessile (meaning attached to a substrate) and has tow notable features:

    1. a contratile stalk that attaches the organism to the substrate

    2. a cell body with a corona of cilia

  • in order for the Vorticella to feed, it has to extend its contractile stalk to push the cell body as far as possible from the substrate and from other individuals

  • then proceeds to beat its cilia rapidly to capture food particles

Apicomplexans (SuperGroup Chromalevolata)

  • Apicomplexans are typically nonmotile parasites of animals

  • these parasites have complex life histories and life stages with various morphologies occurring in multiple hosts

    Plasmodium

  • Its a pathogen which is the best known apicomplexan to be the most common killer of humans in recorded history

  • plasmodium causes malaria, and the mosquitoes transmit the plasmodium from human to human.

    • the parasites infect and rupture red blood cells which causes cycles of fever and chills

    • Sexual reproductive stages occur in the mosquito host and a sexual stages occur in the human host