Protists By: Brianna Dyson Period 1

What are Protists? Microscopic eukaryotes (such as pond scum) Most diverse of all organisms First eukaryotes, thought to have evolved from prokaryotes 1.5 billion years ago through a process called endosymbiosis (when two organisms live together and benefit from each other While most are single celled, some are complex and multicellular.

Classification Classified in the kingdom Protista Vary in body form, nutrition, and reproduction Some show characteristics of plants, animals and fungi, while others lack features that characterize them as any of the three. For example: Red algae can photosynthesize, slime mold can ingest food, and water mold absorb their food, but unlike plants and animals, protists don’t reproduce by forming embryos or develop multicellular reproductive structures. Scientist can informally classify them into three groups: algae (plant-like), protozoa (animal-like), and molds (fungus-like)

Red algaeSlime mold Water mold

Characteristics Very diverse and broad array of characteristics among the eukaryotes of the kingdom Protista Multicellularity (or unicellularity) -multicellularity first developed in different groups of protists at different times -Involves a significant amount of coordination among specialized cells Mitosis and meiosis - asexual reproduction occurs by mitosis - sexual reproduction occurs by meiosis Complex flagella and celia - also appeared first when protists were evolving Sexuality (and/or asexuality) - most protists reproduce asexualy, but during times of environmental stress, they can reproduce sexualy - other protists reproduce sexually most of the time - many protists reproduce only asexually