Lecture 3.2 - Protists

A compilation of key vocabulary terms related to protists, their characteristics, roles, and classifications in biological systems.

Protists

A diverse group of eukaryotic microorganisms that are not classified as plants, animals, or fungi.

Euglena

A protist commonly found in pond water, known for its flagellum and photosynthetic abilities.

Excavata

A clade of protists characterized by a feeding groove and can be predatory heterotrophs, photosynthetic autotrophs, mixotrophs, or parasites.

Giardia intestinalis

A flagellated unicellular eukaryote that is parasitic in the human intestine, causing giardiasis.

Mixotrophs

Protists that combine photosynthesis and heterotrophic nutrition.

Diatoms

A major group of unicellular algae that are a key component of phytoplankton, known for their glass-like walls.

Brown algae

Multicellular algae that are typically found in marine environments and store carbohydrates as laminarin.

Dinoflagellates

A group of protists that possess flagella and are known for causing 'red tides' due to their bloomed populations.

Apicomplexans

A group of almost wholly parasitic protists, including those that cause diseases like malaria.

Plasmodium

The genus of protists that causes malaria in humans, characterized by a complex life cycle involving mosquito and human hosts.

Rhodophyta

A group of red algae which are mostly marine and known for their distinctive pigments.

Chlorophyta

Green algae that are most plant-like and often live in freshwater environments.

Unikonta

A clade that includes protists closely related to fungi and animals, including amoebozoans.

Symbiotic relationships

Interactions between different species where at least one benefits, such as the relationship between corals and zooxanthellae.

Phytoplankton

Aquatic protists responsible for about 30% of global photosynthesis, including diatoms and dinoflagellates.

Parasite

An organism that lives in or on another organism (its host) and benefits at the host's expense.

Most nutritionally diverse of all eukaryotes include

1. Photoautotrophs

2. Heterotrophs

3. Mixotrophs

Photoautotrophs in protists

Contain chloroplasts

Heterotrophs in protists

Absorb organic molecules or ingest larger food particles

Mixotrophs in protists

Combine photosynthesis and heterotrophic nutrition

Supergroups of rotists

• Excavata

• SAR

• Archaeplastida

• Unikonta

Clade excavata

Can be predatory heterotrophs, photosynthetic autotrophs, mixotrophs and parasites

Giardia

Parasite shed in faeces

Giardia protection

Has a protective outer shell → can survive outside the body for long periods and is resistant to chlorine disinfection

SAR clade

Diverse monophyletic group of protists defined by DNA similarities

Stramenopiles

A group within the SAR clade, characterized by hair-like structures on their flagella, including diatoms and brown algae.

Diatoms

Single-celled algae known for their glass-like cell walls made of silica, contributing to oceanic primary production.

Brown algae

A group of large, multicellular marine algae, often ranging in color from olive green to brown, that play a vital role in coastal ecosystems and food webs.

Alveolates

Membrane-enclosed sac under the plasma membrane

Dinoflagellates

a group of single-celled organisms characterized by two flagella and can be photosynthetic or heterotrophic; some species can cause red tides.

Dinoflagellates can produce…

Toxins, and can contaminate invertebrates and fish

Apicomplexans

a group of parasitic protists that utilize apical complex structures to invade host cells, including the species that causes malaria.

Name

Apicomplexans

Plasmodium

a genus of apicomplexan parasites that are responsible for causing malaria in humans. They are transmitted through the bite of infected Anopheles mosquitoes.

Malaria

a disease caused by Plasmodium parasites, transmitted through the bites of infected Anopheles mosquitoes.

Rhodophyta (red algae)

a division of red algae, characterized by their ability to perform photosynthesis using chlorophyll a and accessory pigments. Red algae are primarily found in marine environments.

Chlorophyta (green algae)

a division of green algae that are primarily freshwater organisms, utilizing chlorophyll a and b for photosynthesis. They play a significant role in aquatic ecosystems and are important for oxygen production.

Unikonta

Includes protists that are closely related to fungi and animals as well as fungi and animals

Amoebozoans

a group of protists characterized by their irregular shapes and ability to move using pseudopodia. They are often found in moist environments and include organisms like amoebas.

Symbiotic protists

are protists that live in close association with other organisms, often providing benefits to their hosts, such as nutrient acquisition or protection.

Phytoplankton percentage of photosynthesis

30% all photosynthesis - includes diatoms, dinoflagellates, multicellular algae and other aquatic protests

Parasitic protists

are protists that obtain nutrients and energy by living on or inside a host organism, often causing disease or harm to the host.