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What Are the Main Features of Single-Celled Protists?

  • Protists are in Domain Eukarya and thus have larger, more complex cells than prokaryotes.

  • The 7 supergroups of eukaryotes include many kingdoms of protista as well as the plants, fungi and animals; the land plant-algae supergroup and the Opisthokonta supergroup are of special interest.

  • Protists exhibit great diversity in size, shape and structure.

  • Protists exhibit several types of nutrition and feeding styles.

  • All protists can reproduce asexually, but many of them can also reproduce sexually via meiosis.

    • Some protists utilize the process of conjuation when reproducing sexually.

    • Many protists form cysts as a part of the reproductive process and to survive harsh conditions.

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How do Prokaryotes and Protists Impact Human Life?

  • Some bacteria are harmful pathogens, but no Archaeans are known to cause human disease.

    • The toxins that bacteria secrete cause tissue damage to their hosts.

    • Pathogenic bacteria can enter the body by several routes, but modern antibiotics have reduced the seriousness of bacterial infections.

  • Other bacteria are beneficial to human life as well as to the ecosystem in general.

  • While most protists are beneficial (or even essential) to the ecosystem, some are harmful: a few cause serious human diseases, while others secrete toxins into the water.

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