Protists

A collection of vocabulary flashcards covering key terms related to Eukaryotic Diversity and Protists, including definitions for major concepts and organisms discussed in the lecture notes.

Leeuwenhoek

The father of microbiology who created single lens microscopes with up to 288x magnification and corresponded with England's Royal Society.

Protista

A former kingdom of mostly unicellular eukaryotes, now abandoned, but the term 'protists' still refers to eukaryotes that are neither plants, animals, nor fungi.

Endosymbiosis

A process in which a unicellular organism engulfs another cell, which becomes an endosymbiont and eventually forms organelles in the host cell.

Photoautotrophs

Protists that contain chloroplasts and are plant-like in their nutritional mode.

Heterotrophs

Protists that absorb organic molecules or ingest larger food particles; can be animal-like or fungus-like.

Mixtrophs

Protists that combine photosynthesis and heterotrophic nutrition.

Ciliates

A group of protists that use cilia for feeding and movement, characterized by two types of nuclei (micronuclei and macronuclei).

Diatoms

Unicellular algae with a unique 2-part silicon wall, major components of phytoplankton, usually reproduce asexually.

Red Algae

Multicellular algae, colored due to phycoerythrin, which absorbs blue and green light.

Green Algae

Autotrophic organisms closely related to plants, characterized by their grass-green chloroplasts.

Malaria

A serious disease caused by the Plasmodium parasite, transmitted by Anopheles mosquitoes, leading to severe clinical symptoms.

Dinoflagellates

Protists that can cause toxic blooms known as red tides, characterized by armored cellulose plates and spinning motion.

Why is the kingdom Protista no longer recognized?

It was found to be polyphyletic, meaning its members did not all descend from a single common ancestor. Genetic and morphological evidence showed protists are more diverse than initially thought.

Amoebas

Protists that move and feed by means of pseudopods, which are temporary extensions of the cell.

Euglenids

A group of flagellated protists that often have a pocket at one end from which one or two flagella emerge. Many are mixotrophs.

What is the primary ecological role of many protists?

They are significant primary producers (e.g., photosynthetic algae and diatoms) at the base of aquatic food webs, and some are decomposers.

Protist Habitats

Protists inhabit diverse environments, including aquatic habitats (freshwater, marine), moist terrestrial environments, and as symbionts within other organisms.

Foraminiferans

Amoeboid protists named for their porous shells (tests) made of calcium carbonate, which contribute to marine sediments and are used as indicators in paleoclimatology.

Plasmodial Slime Molds

Also known as 'acellular slime molds,' they form a large, single-celled, multinucleate mass of protoplasm called a plasmodium that engulfs food particles as it grows.

Apical Complex

A specialized organelle found in apicomplexans (parasitic protists like Plasmodium), used to penetrate host cells.

Nutritional diversity of protists

Protists exhibit the most nutritional diversity of all eukaryotes, including photoautotrophs, heterotrophs, and mixotrophs.

What disease is caused by Trypanosoma?

African sleeping sickness, transmitted by the tsetse fly.

What are some of the current eukaryotic 'supergroups' that now encompass organisms formerly known as protists?

Major supergroups include Excavata, SAR clade (Stramenopiles, Alveolates, Rhizarians), Archaeplastida, and Unikonta.

Apicomplexans

A group of parasitic protists, characterized by the presence of an apical complex used for penetrating host cells, and often having complex life cycles involving multiple hosts.

What are the distinct roles of micronuclei and macronuclei in ciliates?

Micronuclei are involved in genetic recombination (sexual reproduction), while macronuclei control the everyday functions of the cell.

What are the environmental and economic impacts of severe dinoflagellate blooms (red tides)?

Red tides can deplete oxygen, kill marine life, and produce toxins that contaminate shellfish, affecting fisheries and human health.

Secondary Endosymbiosis

A process where a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis (e.g., engulfing a red or green algae), leading to more complex plastids with extra membranes.

Supergroup Excavata

A supergroup characterized by modified mitochondria and unique flagella, with many members having an 'excavated' groove on one side of the cell body.

Supergroup SAR Clade

A diverse supergroup comprising Stramenopiles (diatoms, golden algae, brown algae), Alveolates (dinoflagellates, apicomplexans, ciliates), and Rhizarians (foraminiferans, radiolarians, cercozoans).

Supergroup Archaeplastida

This supergroup includes red algae, green algae, and land plants, all descended from an ancient protist that engulfed a cyanobacterium (primary endosymbiosis).

Supergroup Unikonta

A supergroup that includes amoebozoans (slime molds, gymnamoebas, entamoebas) and opisthokonts (animals, fungi, and related protists).