Euglenozoa: Characteristics and Types

Questions and Answers

What is the characteristic feature of Euglenozoa?

Cellulose plates reinforcing the cell

Spiral or crystalline rod inside their flagella (correct)

Single mitochondrion with an organized mass of DNA

Membrane-bounded sacs under the plasma membrane

Dinoflagellates are always phototrophic.

False

The alveolates include Dinoflagellates, Apicomplexans, and _________.

Ciliates

Which of the following is a characteristic of Kinetoplastids?

A single mitochondrion with an organized mass of DNA Signup and view all the answers

Match the following alveolates with their characteristics:

Dinoflagellates = Two flagella and cellulose plates Apicomplexans = Unknown function Ciliates = Abundant components of phytoplankton Signup and view all the answers

Stramenopiles are a subgroup of Alveolata.

False Signup and view all the answers

What is the name of the disease caused by a pathogenic trypanosome?

Chagas' disease Signup and view all the answers

What is the primary function of pseudopodia in radiolarians?

To engulf microorganisms through phagocytosis Signup and view all the answers

Foraminiferans, or forams, have endosymbiotic algae.

True Signup and view all the answers

What is the name of the accessory pigment that masks the green of chlorophyll in red algae?

Phycoerythrin Signup and view all the answers

The supergroup that includes red algae, green algae, and land plants is called _______________.

Archaeplastida Signup and view all the answers

Match the following groups with their characteristics:

Radiolarians = Delicate tests made of silica Foraminiferans = Porous, multichambered shells Red Algae = Reddish in color due to phycoerythrin Green Algae = Grass-green chloroplasts Signup and view all the answers

What is the name of the supergroup that includes animals, fungi, and some protists?

Unikonta Signup and view all the answers

Slime molds, or mycetozoans, are a type of fungi.

False Signup and view all the answers

What is the name of the process by which radiolarians engulf microorganisms?

Phagocytosis Signup and view all the answers

What is true about Apicomplexans?

They are parasites of animals. Signup and view all the answers

Ciliates reproduce by conjugation.

False Signup and view all the answers

What is unique about the wall of diatoms?

It is made of hydrated silica and is two-part and glass-like. Signup and view all the answers

Apicomplexans have a complex of organelles at one end, known as the ______________________, which is specialized for penetrating host cells and tissues.

apex Signup and view all the answers

What is the name of the parasite that causes malaria?

Plasmodium Signup and view all the answers

Match the following groups of protists with their characteristic feature:

Apicomplexans = Have a complex of organelles at one end Ciliates = Use cilia to move and feed Stramenopiles = Have a 'hairy' flagellum paired with a 'smooth' flagellum Diatoms = Have a glass-like wall of hydrated silica Signup and view all the answers

Stramenopiles are only phototrophs.

False Signup and view all the answers

What happens to many dead diatoms after a bloom?

They fall to the ocean floor undecomposed. Signup and view all the answers

What is a characteristic feature of protists?

They are eukaryotic and exhibit variety in shape, patterns, and organelles Signup and view all the answers

All protists are autotrophic.

False Signup and view all the answers

What is endosymbiosis?

The process by which one organism engulfs and incorporates another, often leading to the formation of new organelles. Signup and view all the answers

Protists are classified into four supergroups: _______________, SAR, Archaeplastida, and Opisthokonta.

Excavata Signup and view all the answers

What is the primary mode of nutrition for some protists?

Both of the above Signup and view all the answers

Match the following characteristics with the correct type of protist:

Multicellular = Kelp Unicellular = Euglena Colony-forming = Some protists Exhibits alternation of generations = Kelp Signup and view all the answers

All protists reproduce sexually.

False Signup and view all the answers

What is mixotrophy?

The ability to switch between autotrophic and heterotrophic metabolism. Signup and view all the answers

What is the characteristic feature of the cytoskeleton of Excavates?

A groove on one side, giving it an excavated appearance Signup and view all the answers

Diplomonaads are always parasites.

True Signup and view all the answers

What is the by-product of the metabolic pathways of Parabasalids?

hydrogen gas Signup and view all the answers

Euglenozoa have a kinetic plastid, which is a single large _______________ with a large mass of DNA.

mitochondrion Signup and view all the answers

What is the mode of nutrition of Neuglenida?

Mixotrophic Signup and view all the answers

Excavates have modified mitochondria called microsomes.

False Signup and view all the answers

Match the following subgroups of Excavates with their characteristics:

Diplomonaads = Have modified mitochondria called microsomes Parabasalids = Produce hydrogen gas as a by-product of their metabolic pathways Euglenozoa = Have a rod-shaped structure within their flagella Neuglenida = Are mixotrophic Signup and view all the answers

What is an example of a Neuglenida?

Euglena Signup and view all the answers

What is the common characteristic of Alveolates?

Presence of membrane-bound air pockets called alveoli Signup and view all the answers

Dinoflagellates are always parasitic.

False Signup and view all the answers

What is the unique feature of the cell wall of diatoms?

The cell wall is made of hydrated silicon dioxide Signup and view all the answers

Apicomplexans are responsible for diseases such as ______________________, which affects millions of people worldwide.

malaria Signup and view all the answers

Match the following Stramenopiles with their characteristics:

Diatoms = Single-celled organisms with a frustule made of hydrated silicon dioxide Golden Algae = Flagellated and mixotrophic Brown Algae = Multicellular organisms with a brown pigment Signup and view all the answers

What is the characteristic feature of Ciliates?

Presence of rows of cilia on their cell surface Signup and view all the answers

Stramenopiles are only phototrophs.

False Signup and view all the answers

What is the unique feature of the life cycle of Brown Algae?

Alternation of generations Signup and view all the answers

Golden Algae are characterized by the presence of a ______________________ pigment that gives them their yellowish color.

golden Signup and view all the answers

What is the name of the subgroup that consists of Stramenopiles, Alveolates, and Rhizaria?

SAR clade Signup and view all the answers

What is a characteristic feature of brown algae?

They have structures that resemble those found in plants. Signup and view all the answers

Red algae appear blue due to the presence of phycoerythrin.

False Signup and view all the answers

What is the primary function of the holdfast in brown algae?

The primary function of the holdfast is to anchor the algae to rocks or substrate. Signup and view all the answers

The life cycle of brown algae involves an alternation of _______________________ generations.

diploid and haploid Signup and view all the answers

Match the following types of algae with their characteristics:

Red Algae = Abundance of phycoerythrin Green Algae = Mostly multicellular and live in freshwater or ocean Brown Algae = Multicellular with structures that resemble plants Signup and view all the answers

Stramenopiles are a group that includes red and green algae.

False Signup and view all the answers

What is the supergroup that includes red and green algae?

RK Plastid Signup and view all the answers

The life cycle of brown algae involves the production of _______________________ through meiosis.

spores Signup and view all the answers

What is the primary function of pseudopodia in amoeboid protists?

Locomotion and capturing prey Signup and view all the answers

All amoeboid protists are Autotrophic.

False Signup and view all the answers

What is the characteristic feature of slime molds?

Slime molds have a mesh-like network of cytoplasm and nuclei, and can form a sporangium when conditions become unfavorable. Signup and view all the answers

Uniconta includes amoeboid protists, animals, and _______________.

fungi Signup and view all the answers

Match the following amoeboid protists with their characteristics:

Radial Ariens = Have tests made of silica. Foramenifera = Have tests made of calcium carbonate. Tubulinians = Move using cytoplasmic streaming. Slime Molds = Have a mesh-like network of cytoplasm and nuclei. Signup and view all the answers

Some Foramenifera have endosymbiotic algae that help with obtaining sugar through photosynthesis.

True Signup and view all the answers

What is the name of the disease caused by Entamoeba histolytica?

Amoebic dysentery Signup and view all the answers

What is the name of the supergroup that includes amoeboid protists, animals, and fungi?

Uniconta Signup and view all the answers

Study Notes

Apicomplexans

Apicomplexans are parasites of animals, causing serious human diseases.
They spread through their host as infectious cells called sporozoites.
The apex of apicomplexans contains a complex of organelles specialized for penetrating host cells and tissues.
Most apicomplexans have sexual and asexual stages that require two or more different host species for completion.
Plasmodium, an apicomplexan, causes malaria, requiring both mosquitoes and humans to complete its life cycle.
Approximately 900,000 people die each year from malaria, and efforts are ongoing to develop vaccines that target this pathogen.

Ciliates

Ciliates are a large, varied group of protists named for their use of cilia to move and feed.
They have large macronuclei and small micronuclei.
Genetic variation results from conjugation, a sexual process in which two individuals exchange haploid micronuclei, separate from reproduction, which occurs by binary fission.

Stramenopila

Stramenopila is a subgroup that includes important phototrophs and several clades of heterotrophs.
Most stramenopiles have a “hairy” flagellum paired with a “smooth” flagellum.
Stramenopiles include diatoms, golden algae, brown algae, and oomycetes.

Diatoms

Diatoms are unicellular algae with a unique two-part, glass-like wall of hydrated silica.
Diatoms are a major component of phytoplankton and are highly diverse.
Fossilized diatom walls compose much of the sediments known as diatomaceous earth.
After a diatom population has bloomed, many dead individuals fall to the ocean floor undecomposed.
Reproduction is mainly asexual.

Euglenozoa

Euglenozoa is a diverse clade that includes euglenids and kinetoplastids.
Some euglenozoans are predatory heterotrophs, photosynthetic autotrophs, and parasites.
The main feature distinguishing them as a clade is a spiral or crystalline rod of unknown function inside their flagella.
Euglenids have one or two flagella that emerge from a pocket at one end of the cell.

Kinetoplastids

Kinetoplastids have a single mitochondrion with an organized mass of DNA called a kinetoplast.
They include free-living consumers of prokaryotes in freshwater, marine, and moist terrestrial ecosystems.
This group includes Trypanosoma gambiense, which causes sleeping sickness in humans, and another pathogenic trypanosome that causes Chagas’ disease leading to congestive heart failure.

SAR

The supergroup SAR is thought to be monophyletic and originated by a secondary endosymbiosis event with a red alga as the proposed endosymbiont.
This clade includes the alveolates and the stramenopiles.

Alveolata

Alveolates have membrane-bounded sacs (alveoli) just under the plasma membrane, with unknown function.
The alveolates include dinoflagellates, apicomplexans, and ciliates.

Dinoflagellates

Dinoflagellates have two flagella and each cell is reinforced by cellulose plates.
They are abundant components of both marine and freshwater phytoplankton.
They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs.
Toxic “red tides” are caused by dinoflagellate blooms.

Marine Protists

Radiolarians have tests fused into one delicate piece, usually made of silica.
Radiolarians use their pseudopodia to engulf microorganisms through phagocytosis.
The pseudopodia of radiolarians radiate from the central body.

Foraminiferans

Foraminiferans, or forams, are named for porous, generally multichambered shells, called tests.
Pseudopodia extend through the pores in the test.
Foram tests in marine sediments form an extensive fossil record.
Many forams have endosymbiotic algae.

Archaeplastida

Archaeplastida is the supergroup that includes red algae, green algae, and land plants.

Rhodophyta (Red Algae)

Red algae are reddish in color due to an accessory pigment called phycoerythrin.
The color varies from greenish-red in shallow water to dark red or almost black in deep water.
Red algae are usually multicellular; the largest are seaweeds.
Red algae are the most abundant large algae in coastal waters of the tropics.

Green Algae

Green algae are named for their grass-green chloroplasts.
Plants are descended from the green algae.
Green algae are a paraphyletic group.
The two main groups are chlorophytes and charophytes, the most closely related to land plants.
Most chlorophytes live in fresh water, although many are marine.

Unikonta

The supergroup Unikonta includes animals, fungi, and some protists.
This group includes the amoebozoans and the opisthokonts (animals, fungi, and related protists).
The root of the eukaryotic tree remains controversial.

Definition and Diversity of Protists

Eukaryotic organisms with variety in shape, patterns, and organelles
Exhibit diversity in shape, patterns, and organelles

History of Protist Classification

Originally classified as a "dump bin" for organisms that didn't fit into other categories
Kingdom Protista dismantled in the 1990s and replaced with four supergroups of protists

Characteristics of Protists

Most are unicellular and eukaryotic, but some are multicellular (e.g., kelp)
Some live in colonies, but cells don't show the same level of interaction as tissue cells
Exhibit diversity in subcellular structures (organelles) used for survival

Nutrition and Metabolism

Some are photoautotrophs, using photosynthesis to produce their own food
Others are heterotrophic, obtaining energy by ingesting or absorbing nutrients
Some can switch between autotrophic and heterotrophic metabolism (mixotrophy)
Examples of mixotrophs include Euglena, which have chloroplasts for photosynthesis and can also engulf other cells

Reproduction and Life Cycles

Some reproduce asexually, while others use meiosis to produce nuclei for sexual reproduction and fertilization
Some exhibit alternation of generations, with two distinct generations needed to complete one life cycle
Examples include kelp, which exhibits alternation of generations

Symbiosis and Endosymbiosis

Endosymbiosis is the process by which one organism engulfs and incorporates another, often leading to the formation of new organelles
Mitochondria and chloroplasts originated through endosymbiosis

Classification of Protists

Classified into four supergroups: Excavata, SAR, Archaeplastida, and Opisthokonta
Each supergroup has a hypothesized common ancestor, and the phylogenetic tree demonstrates that protists are polyphyletic (multiple ancestors)

Protist Super Groups

Protists are divided into five super groups based on morphological and DNA data.

Eska Bates (Excavates)

Characterized by unique cytoskeletons with a groove on one side, giving an excavated appearance.
Have modified mitochondria and flagella that differ from other organisms.

Subgroups of Excavates

Diplomonaads

Have modified mitochondria called microsomes, lacking an electron transport chain.
Use anaerobic pathways to generate energy and have two nuclei.
Often parasitic, with examples including Giardia lamblia, which causes hiker sickness.

Parabasalids

Have a reduced number of mitochondria and are anaerobic.
Produce hydrogen gas as a by-product of their metabolic pathways.
Examples include Trichomonas vaginalis, a sexually transmitted disease.

Euglenozoa

Have a rod-shaped structure within their flagella.
Possess a kinetic plastid, a single large mitochondrion with a large mass of DNA.
Can be free-living or parasitic, with examples including Trypanosoma, which causes African sleeping sickness.

Neuglenida

Have a pocket at one end of their flagella.
Are mixotrophic, able to undergo photosynthesis or ingest other organisms to obtain energy.
Examples include Euglena, a common microscopic organism found in pond water.

SAR Clade

Consists of three monophyletic subgroups: Stramenopiles, Alveolates, and Rhizaria
Developed from an endosymbiont, a form of red alga consumed by a heterotrophic eukaryote

Alveolates

Characterized by membrane-bound air pockets called alveoli
Alveoli are similar in composition to respiratory gases like oxygen and carbon dioxide
Examples include dinoflagellates, apicomplexans, and ciliates

Dinoflagellates

Photoautotrophic and heterotrophic, producing food through photosynthesis and consuming other organisms
Have two flagella, one at the terminal end and one around the central groove
Can cause red tides, producing toxins that harm marine life
Can cause severe gastrointestinal poisoning in humans who consume contaminated shellfish

Apicomplexans

Parasitic, infecting a wide range of hosts, including mosquitoes and humans
Have a complex life cycle involving multiple hosts and developmental stages
Responsible for diseases such as malaria, affecting millions worldwide
Have a "bait and switch" strategy, changing surface proteins to evade the host's immune system

Ciliates

Characterized by rows of cilia on their cell surface
Capable of sexual and asexual reproduction
Have a complex life cycle involving conjugation, where two individuals exchange genetic material
Important part of aquatic ecosystems, serving as predators and prey

Stramenopiles

Diverse group including diatoms, golden algae, brown algae, and oomycetes
Characterized by a hairy flagellum and a smooth flagellum
Range of nutritional strategies, including photoautotrophy and heterotrophy
Examples include diatoms, golden algae, and brown algae

Diatoms

Single-celled organisms found in freshwater and marine environments
Important primary producers in aquatic ecosystems
Have a unique cell wall called a frustule, made of hydrated silicon dioxide
Reproduce through binary fission and serve as a food source for many aquatic organisms

Golden Algae

Characterized by a golden pigment, giving them a yellowish color
Typically flagellated and mixotrophic, switching between autotrophy and heterotrophy
Often colonial and found in freshwater and marine environments
Play an important role in aquatic ecosystems, serving as producers and decomposers

Brown Algae

Multicellular organisms found in marine environments
Characterized by a brown pigment and a range of forms, from simple filaments to complex kelps
Important part of marine ecosystems, providing food and habitat for many organisms
Have a unique life cycle involving alternation of generations, where a diploid sporophyte generation produces haploid gametophytes through meiosis

Brown Algae

Multicellular organisms with plant-like structures (holdfast, stipe, blades)
Holdfast anchors algae to rocks/substrate, but doesn't absorb nutrients; surfaces absorb nutrients directly
Life cycle involves alternation of generations: sporophyte (diploid) → spores → gametophyte (haploid) → gametes → fertilization → new sporophyte
Examples: Sargasso, kelp

Alternation of Generations

Life cycle where diploid and haploid generations alternate
Sporophyte generation produces spores through meiosis; spores develop into gametophyte generation
Gametophyte generation produces gametes; fertilization produces new sporophyte generation

Red Algae

Characterized by abundance of phycoerythrin, making them appear red, bluish, purple, or green
Edible varieties used in sushi, e.g., nori
Examples: nori, other edible types

Green Algae

Mostly multicellular; live in freshwater (filamentous algae) or ocean (e.g., sea lettuce)
Important contributors to aquatic food chain
Examples: spirogyra, volvox, sea lettuce, caulerpa

Other Details

Stramenopiles: group including brown algae, characterized by two flagella (smooth and hairy)
RK Plastid: supergroup including red and green algae, indicating ancient origins and presence of chloroplasts for photosynthesis

Amoeboid Protists

Amoeboid protists move using pseudopodia, thin extensions of the cytoplasm used for locomotion and capturing prey
Classified into two groups: Ryze area and Uniconta

Characteristics of Ryze Area

A subgroup of SAR (Supergroup)
Includes Radial Ariens and Foramenifera
Radial Ariens:
- Have tests made of silica (similar to glass)
- Tests have beautiful patterns and shapes
- Pseudopodia used for locomotion and capturing prey
Foramenifera:
- Have tests made of calcium carbonate
- Tests have perforations (little tiny holes) for pseudopodia to emerge
- Some have endosymbiotic algae that help with obtaining sugar through photosynthesis

Uniconta Characteristics

Includes amoeboid protists, animals, and fungi
A controversial group, with scientists unsure of the common ancestor
Molecular similarities, such as similarities in protein and DNA structure, unite the group
Amoeboid protists in Uniconta include slime molds and tubulinians

Slime Molds

Also known as cellular slime molds
Characteristics:
- Made up of many cells without plasma membranes dividing them
- Have a mesh-like network of cytoplasm and nuclei
- Can form a sporangium (reproductive structure) when conditions become unfavorable
- Spores undergo meiosis and germinate into haploid amoeba cells
Form multicellular aggregates, migrate and feed, eventually forming a fruiting body that releases spores
Examples include Dictyostelium

Tubulinians

Formerly known as Gemmyna, move using cytoplasmic streaming
Characteristics:
- Have a lobe-like type of pseudopodium
- Heterotrophic, feeding on other protists, algae, and bacteria
- Not typically known to be parasites, but some amoebas can be severe parasites that can cause deadly diseases
- Examples include Entamoeba histolytica, known for causing gastrointestinal disease

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Description

Learn about the diverse clade Euglenozoa, including euglenids and kinetoplastids, their features, and functions. Discover the unique characteristics that define them as a clade.