Biology 11 – The Protists Study Guide

  1. The Kingdom Protista consists of organisms that are eukaryotic, which are organisms whose cells have nuclei and membrane-enclosed organelles. Members of the Kingdom Protista are known as protists. Protists are defined as unicellular, or single-celled, eukaryotic organisms. However, some protists are multicellular. Many protists live individually, but some are colonial, which means they live in groups of the same species and are attached to each other. They are heterotrophic or autotrophic organisms. The oldest fossils of protists are only about 1.5 billion years old. Protists are organized into two groups, one is animallike protists and one is plantlike protist.  

  1. Prokaryotes are single-celled organisms whose cells do not have a nucleus. Eukaryotes are organisms made up of cells that have a nucleus and its organelles are membrane-bounded.

  1. The Endosymbiotic Hypothesis was proposed by Lynn Margulis. It is a hypothesis that suggests that eukaryotic cells were created from symbiotic relationships between different monerans around 1.5 billion years ago. Prokaryotes lived inside another moneran as endosymbionts, which are symbiotic organisms that live within another organism (the host organism). They benefited each other and eventually the endosymbionts lost its independence and must live with the host cell and inside it. It gave rise to the organelles that we see today in eukaryotic cells.

                                                                             

3 structural features of the mitochondrion:

- has its own DNA with a slightly different genetic code and its own ribosomes

- is enclosed in a double membrane

- replicated through binary fission, like bacteria

  1. The nucleus became surrounded by a double membrane because when it became reliant to the host cell, in order to stop macromolecules from diffusing freely between the nucleoplasm and the cytoplasm, a double membrane must be formed to act as a barrier.
  2. Phylum Ciliophora:
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- all have cilia to move

- has two types of nucleus (macronucleus and micronucleus)

- has trichocysts for defense

- reproduce by binary fission

- involved in a modified type of sexual reproduction: conjugation

- eg. paramecium

Phylum Zoomastigina:

- uses flagella to move

- no shells or cases surrounding membrane

- heterotrophic, absorb nutrients through cell membrane

- reproduce through binary fission

- reproduce sexually by forming gametes

- eg. Trypanosomiases

Phylum Sporozoa:

- nonmotile parasites

- reproduce by means o spores

- eg. Plasmodium

Phylum Sarcodina:

- use pseudopods for feeing and movement

- ...

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