Module 8- The protists bio1108L

Radiolarian

• Thread-like pseudopods – These are thin, extended projections of cytoplasm that radiolarians use for movement and capturing food. The thread-like pseudopods help them trap prey, such as small plankton.

• Heterotrophic – This means radiolarians cannot produce their own food (like plants do). Instead, they consume other organisms (such as bacteria or small plankton) to obtain nutrients.

Spirogyra

a filamentous green algae known for its spiral-shaped chloroplasts.

Saragassum

Leaf-like blades with air bladders

Diatoms

Over-lapping valves, cell wall contains silica

Dinoflagellates

some cause toxic red tides

Paramecium

Is a ciliate

Red Algae

Red algae (Rhodophyta) are a group of photosynthetic algae known for their red color, which comes from a unique pigment called phycoerythrin.

Slime mold

An amoebozoan

An amoebozoan is a type of protist in the group Amoebozoa, characterized by its ability to move and engulf food using pseudopodia

Primary endosymbiosis

the process in which a eukaryotic cell engulfs a prokaryotic cell, and instead of digesting it, the engulfed cell becomes a symbiotic organelle within the host. This process led to the formation of mitochondria and chloroplasts in eukaryotic cells.

In this process the endosymbiont is the prokaryotic cell.

Secondary Endosymbiosis

Secondary endosymbiosis occurs when a eukaryotic cell engulfs another eukaryotic cell that already contains an endosymbiont (like a chloroplast). This process led to the diversity of photosynthetic protists, such as dinoflagellates, euglenoids, diatoms, and brown algae.

The endosymbiont is a eukaryotic cell.

Extra info on protists

Organisms in domain Eukarya are currently divided into four supergroups: Excavata, SAR, Archaeplastida, and Unikonta.

The term "protist" is used to describe any eukaryotic organism that is NOT a plant, fungus, or animal.

Protists form a paraphyletic grouping.

since they form a paraphyletic group, there are no synapomorphies that define the protists.  In other words, there is no one characteristic that they all have in common but is not shared with other eukaryotic groups.

Protists obtain their energy either via photosynthesis, heterotrophy, or mixotrophy. Mixotrophic protists are those that can perform photosynthesis and heterotrophy. Many euglenoids and dinoflagellates are mixotrophic.

Eyespot

A light sensing organelle found in some flagellate algae

Agar

A chemical extracted from some species of red algae that is used as a gelling, thickening, or stabilizing agent.

Carrageenan

a chemical extracted from some species of red algae that can be used as a gelling, thickening, or stabilizing agent

Blade

forms the main portion of a macroscopic alga's body 

Holdfast

the portion of an algal body that attaches it to the substrate

Stipe

a narrowed portion of an alga located between the blade and the holdfast; not present in all species

Air bladders

structures filled with gas that allow algal blades to float; found in some species of brown algae

Vacuole

A storage organelle

Test

unicellular protists, this is used to describe a hardened internal shell (sometimes referred to as the skeleton)

Pellicle

often a flexible cell covering that may allow for cellular movement or changes to the cell shape

Pseudopods

temporary projection of the cell membrane used for movement and food capture

Sporangium

spore producing structure

Excavata

This supergroup includes the euglenozoans, and diplomonads. Some members of this supergroup possess an excavated feeding groove, which gives this group its name. The euglenozoans possess a pellicle, which allows for euglenoid movement in many species.

SAR Clade

The SAR supergroup is composed of three closely related lineages: Stramenopiles, Alveolates, and Rhizari.ans. This supergroup's name is derived from the first letter of each of the three subgroups. Stramenopiles: all cells with flagella have two structurally different flagella, one with hairs and one that is smooth. Alveolates: possess alveoli (membrane-enclosed sacs) under the plasma membrane for support. Rhizarians: unicellular with thread-like pseudopods

Archaeplastida

includes: Red algae, green algae, and Land plants 🌱🔴

✅ Chloroplasts from Primary Endosymbiosis – Evolved from a cyanobacterium engulfed by an ancestral eukaryote.
✅ Photosynthetic Pigments – All have chlorophyll a.

• Green algae & land plants also have chlorophyll b (green).

• Red algae have phycoerythrin, allowing them to absorb deeper light.
  ✅ Land Plants Evolved from Green Algae – Specifically Charophytes, which share key traits with plants.

Unikonta

is composed of two lineages, the Amoebozoa (slime molds, amoeba) and Opisthokonta (fungi, animals, choanoflagellates). The close relationship of these two lineages is supported by comparisons of myosin proteins and molecular sequence studies.

Gametophyte and sporophyte dominant groups

Bryophytes (mosses, liverworts, and hornworts) and some algae (red and green) are gametophyte dominant.

Vascular plants (Ferns and Fern allies) (seedless Vascular Plants) are sporophyte dominant.

Gymnosperms & angiosperms are sporophyte dominant.